Publications by authors named "Ping Chai"

59 Publications

One-year outcomes of patients with ST-segment elevation myocardial infarction during the COVID-19 pandemic.

J Thromb Thrombolysis 2021 Aug 26. Epub 2021 Aug 26.

Department of Cardiology, National University Heart Center, National University Health System, Singapore, Singapore.

The pandemic has led to adverse short-term outcomes for patients with ST-segment elevation myocardial infarction (STEMI). It is unknown if this translates to poorer long-term outcomes. In Singapore, the escalation of the outbreak response on February 7, 2020 demanded adaptation of STEMI care to stringent infection control measures. A total of 321 patients presenting with STEMI and undergoing primary percutaneous coronary intervention at a tertiary hospital were enrolled and followed up over 1-year. They were allocated into three groups based on admission date-(1) Before outbreak response (BOR): December 1, 2019-February 6, 2020, (2) During outbreak response (DOR): February 7-March 31, 2020, and (3) control group: November 1-December 31, 2018. The incidence of cardiac-related mortality, cardiac-related readmissions, and recurrent coronary events were examined. Although in-hospital outcomes were worse in BOR and DOR groups compared to the control group, there were no differences in the 1-year cardiac-related mortality (BOR 8.7%, DOR 7.1%, control 4.8%, p = 0.563), cardiac-related readmissions (BOR 15.1%, DOR 11.6%, control 12.0%, p = 0.693), and recurrent coronary events (BOR 3.2%, DOR 1.8%, control 1.2%, p = 0.596). There were higher rates of additional PCI during the index admission in DOR, compared to BOR and control groups (p = 0.027). While patients admitted for STEMI during the pandemic may have poorer in-hospital outcomes, their long-term outcomes remain comparable to the pre-pandemic era.
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http://dx.doi.org/10.1007/s11239-021-02557-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8390088PMC
August 2021

Age- and Sex-Specific Changes in CMR Feature Tracking-Based Right Atrial and Ventricular Functional Parameters in Healthy Asians.

Front Cardiovasc Med 2021 4;8:664431. Epub 2021 Jun 4.

National Heart Centre Singapore, Singapore, Singapore.

Cardiovascular magnetic resonance (CMR) is the reference standard for non-invasive assessment of right-sided heart function. Recent advances in CMR post-processing facilitate quantification of tricuspid annular (TA) dynamics and longitudinal strains of the right ventricle (RV) and right atrium (RA). We aimed to determine age- and sex-specific changes in CMR-derived TA dynamics, and RV and RA functional parameters in healthy Asian adults. We studied 360 healthy subjects aged 21-79 years, with 30 men and 30 women in each of the six age groups. Functional parameters of RV and RA were measured on standard four-chamber cine CMR using fast feature tracking: (1) TA peak velocities (systolic velocity S', early diastolic velocity E', late diastolic velocity A') and TA plane systolic excursion (TAPSE); (2) RV global longitudinal strain (GLS) and strain rates; and (3) RA phasic longitudinal strains and strain rates. S' and TAPSE exhibited negative correlations with age. RV GLS was significantly higher in females than in males but not associated with age in both sexes. Females had similar E', lower A', and higher E'/A' ratios compared to males. Positive associations of E' and E'/A', and negative association of A' with age were observed in both sexes. Females had higher RA reservoir and conduit strains compared to males. There were significantly negative and positive associations between RA conduit and booster strains, respectively, with age. Age- and sex-specific reference ranges were established, and associations revealed, for fast CMR feature tracking parameters of right heart function in a large normal Asian population.
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http://dx.doi.org/10.3389/fcvm.2021.664431DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8213369PMC
June 2021

Impact of age, sex and ethnicity on intra-cardiac flow components and left ventricular kinetic energy derived from 4D flow CMR.

Int J Cardiol 2021 08 25;336:105-112. Epub 2021 May 25.

National Heart Research Institute Singapore, National Heart Centre Singapore, 5 Hospital Drive, 169609, Singapore; Duke-NUS Medical School, National University of Singapore, 8 College Road, 169857, Singapore. Electronic address:

Background: Four-dimensional flow cardiovascular magnetic resonance (4D flow CMR) allows quantification of left ventricular (LV) blood flow. We aimed to 1) establish reference ranges for 4D flow CMR-derived LV relative flow components and kinetic energy parameters indexed to end-diastolic volume (KEi) among healthy Asian subjects, 2) assess effects of age and sex on these parameters, and 3) compare these parameters between Asian and Caucasian subjects.

Methods: 74 healthy Asian subjects underwent cine and 4D flow CMR. Relative flow components (direct flow, retained inflow, delayed ejection flow, residual volume) and multiple phasic KEi (LV global, peak systolic, systolic, diastolic, peak E-wave, peak A-wave) were analyzed. Sex- and age-specific reference ranges were reported.

Results: Relative flow components and systolic phase KEi did not vary with age. Women had higher retained inflow and peak E-wave KEi, lower residual volume, peak systolic and systolic KEi than men. Peak A-wave KEi increased significantly (r = 0.474) whereas peak E-wave KEi (r = -0.458) and E-wave/A-wave ratio (r = -0.528) decreased with age. A sub-population (n = 44) was compared with 44 sex- and age-matched Caucasian subjects: no significant group differences were observed for all 4D flow CMR parameters.

Conclusion: Asian sex- and age-specific 4D flow CMR reference ranges were established. Sex differences in retained inflow, residual volume, peak systolic, systolic KEi and peak E-wave KEi were observed. Ageing influenced diastolic KEi but not systolic phase KEi or relative flow components. All studied parameters were similar between sex- and age-matched Asian and Caucasian subjects, implying generalizability of the ranges.
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http://dx.doi.org/10.1016/j.ijcard.2021.05.035DOI Listing
August 2021

Comparison of the Efficacy and Safety of Direct Oral Anticoagulants and Vitamin K Antagonists in Patients with Atrial Fibrillation and Concomitant Liver Cirrhosis: A Systematic Review and Meta-Analysis.

Am J Cardiovasc Drugs 2021 May 19. Epub 2021 May 19.

Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.

Background: Patients with atrial fibrillation (AF) have a higher risk of developing thromboembolic events. Current guidelines recommend the use of oral anticoagulants for stroke prevention in these patients. Several clinical trials demonstrated that direct oral anticoagulants (DOACs) have similar efficacy and are safer alternatives to traditional oral anticoagulants. However, patients with concomitant liver cirrhosis were excluded from these trials.

Objective: We aimed to systematically identify and review published clinical studies on the use of DOACs in patients with AF and liver cirrhosis and assess the efficacy and safety of DOACs in these patients.

Methods: A systematic review of clinical trials and retrospective studies was conducted by searching the PubMed, Cochrane Library, Embase, SCOPUS, and Web of Science databases up to September 2020.

Results: Three retrospective studies were included, involving 4011 patients with AF and liver cirrhosis. The use of DOACs was associated with a significant reduction in ischemic stroke (hazard ratio [HR] 0.62; 95% confidence interval [CI] 0.42-0.90; p = 0.01), major bleeding events (HR 0.64; 95% CI 0.57-0.72; p < 0.001), and intracranial hemorrhage (HR 0.49; 95% CI 0.40-0.59; p < 0.001).

Conclusions: Compared with warfarin in patients with AF and liver cirrhosis, DOACs appear to be associated with improved efficacy and safety outcomes. Randomized controlled trials are warranted to confirm these findings.
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http://dx.doi.org/10.1007/s40256-021-00482-wDOI Listing
May 2021

Effects of Colchicine on Cardiovascular Outcomes in Patients with Coronary Artery Disease: A Systematic Review and One-Stage and Two-Stage Meta-Analysis of Randomized-Controlled Trials.

High Blood Press Cardiovasc Prev 2021 Jul 18;28(4):343-354. Epub 2021 May 18.

Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.

Aim: Colchicine has received emerging interest due to its cardiovascular benefits in patients with coronary artery disease (CAD). We conducted a one-stage meta-analysis of reconstructed individual patient data (IPD) from randomized-controlled trials to summarize the effects of colchicine on cardiovascular outcomes in patients with CAD.

Methods: Four databases (PubMed, Embase, Cochrane, SCOPUS) were searched for articles published from inception to 30th September 2020, examining the effect of colchicine on cardiovascular outcomes in patients with CAD, yielding 10 randomized-controlled trials with a combined cohort of 12,781 patients. IPD was reconstructed from Kaplan-Meier curves published in 3 studies and analysed using the shared-frailty Cox model. Aggregate data meta-analysis of all 10 studies was performed for outcomes unsuitable for IPD reconstruction.

Results: In patients receiving colchicine compared to placebo, one-stage meta-analysis demonstrated a hazard ratio of 0.70 (95% CI 0.61-0.80) for the composite outcome of cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, and urgent hospitalization for angina requiring coronary revascularization. Aggregate data meta-analysis demonstrated a significant reduction in hazard rate for stroke (HR 0.45; 95% CI 0.27-0.75) and urgent revascularization (HR 0.59; 95% CI 0.38-0.91); and a relative risk reduction for myocardial infarction (RR 0.72; 95% CI of 0.52-1.00) and post-operative atrial fibrillation (RR 0.64; 95% CI 0.48-0.86).

Conclusion: Given the significant benefits of colchicine demonstrated on IPD, and its consistent benefits when analyzed using aggregate data meta-analysis, we propose that colchicine may be considered as an additional pharmacological adjunct to the first line therapy for patients with coronary artery disease.
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http://dx.doi.org/10.1007/s40292-021-00460-yDOI Listing
July 2021

Comparing the clinical outcomes across different sodium/glucose cotransporter 2 (SGLT2) inhibitors in heart failure patients: a systematic review and network meta-analysis of randomized controlled trials.

Eur J Clin Pharmacol 2021 Oct 3;77(10):1453-1464. Epub 2021 May 3.

Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.

Purpose: Empagliflozin, dapagliflozin, canagliflozin, and ertugliflozin have been shown in randomized controlled trials to improve cardiovascular, metabolic, and renal outcomes in heart failure patients. To date, there has not been any meta-analysis examining the differences in clinical outcomes across different SGLT2 inhibitors in heart failure patients.

Methods: Four electronic databases (PubMed, Embase, Cochrane, SCOPUS) were searched on 13 September 2020 for articles published from 1 January 2000 to 13 September 2020 examining the effect of SGLT2 inhibitors on cardiovascular, renal, and metabolic outcomes in heart failure patients. Frequentist network meta-analysis was performed on extracted data.

Results: Ten randomized controlled trials were included with a combined cohort of 15,373 patients. In heart failure patients, frequentist network meta-analysis demonstrated no demonstrable difference in treatment effect across the SGLT2 inhibitors for heart failure hospitalization, cardiovascular deaths, composite of cardiovascular deaths and heart failure hospitalizations, all-cause mortality, and a composite of cardiovascular deaths and non-fatal myocardial infarction and non-fatal stroke. There was no demonstrable difference in treatment effect for worsening renal function or the weighted mean difference for weight, hemoglobin A1c, and systolic blood pressure.

Conclusions: There were no demonstrable treatment differences across SGLT2 inhibitors across cardiovascular, renal, and metabolic outcomes, although this needs to be interpreted considering the wide confidence intervals, limited number of included studies, and heterogeneity present. Future research of different SGLT2 inhibitors in head-to-head studies is warranted to determine if there is a drug class effect.
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http://dx.doi.org/10.1007/s00228-021-03147-4DOI Listing
October 2021

Cardiovascular magnetic resonance-assessed fast global longitudinal strain parameters add diagnostic and prognostic insights in right ventricular volume and pressure loading disease conditions.

J Cardiovasc Magn Reson 2021 04 1;23(1):38. Epub 2021 Apr 1.

National Heart Research Institute Singapore, National Heart Centre Singapore, 5 Hospital Drive, 169609, Singapore, Singapore.

Background: Parameters of myocardial deformation may provide improved insights into right ventricular (RV) dysfunction. We quantified RV longitudinal myocardial function using a fast, semi-automated method and investigated its diagnostic and prognostic values in patients with repaired tetralogy of Fallot (rTOF) and pulmonary arterial hypertension (PAH), who respectively exemplify patients with RV volume and pressure overload conditions.

Methods: The study enrolled 150 patients (rTOF, n = 75; PAH, n = 75) and 75 healthy controls. RV parameters of interest were fast global longitudinal strain (GLS) and strain rates during systole (GLSR), early diastole (GLSR) and late diastole (GLSR), obtained by tracking the distance from the medial and lateral tricuspid valve insertions to the RV epicardial apex on cine cardiovascular magnetic resonance (CMR).

Results: The RV fast GLS exhibited good agreement with strain values obtained by conventional feature tracking approach (bias - 4.9%, error limits (± 2·standard deviation) ± 4.3%) with fast GLS achieving greater reproducibility and requiring reduced analysis time. Mean RV fast GLS was reduced in PAH and rTOF groups compared to healthy controls (PAH < rTOF < healthy controls: 15.1 ± 4.9 < 19.3 ± 2.4 < 24.4 ± 3.0%, all P < 0.001 in pairwise comparisons). In rTOF patients, RV fast GLS was significantly associated with metabolic equivalents, peak oxygen consumption (PVO) and percentage of predicted PVO achieved during cardiopulmonary exercise testing. Lower RV fast GLS was associated with subnormal exercise capacity in rTOF (area under the curve (AUC) = 0.822, sensitivity = 72%, specificity = 91%, cut-off = 19.3%). In PAH patients, reduced RV fast GLS was associated with RV decompensated hemodynamics (AUC = 0.717, sensitivity = 75%, specificity = 58%, cut-off = 14.6%) and higher risk of clinical worsening (AUC = 0.808, sensitivity = 79%, specificity = 70 %, cut-off = 16.0%).

Conclusions: Quantitative RV fast strain and strain rate parameters assessed from CMR identify abnormalities of RV function in rTOF and PAH and are predictive of exercise capacity, RV decompensation and clinical risks in these patients. Trial registry Clinicaltrials.gov: NCT03217240.
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http://dx.doi.org/10.1186/s12968-021-00724-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8015087PMC
April 2021

Association between smoking status and outcomes in myocardial infarction patients undergoing percutaneous coronary intervention.

Sci Rep 2021 03 19;11(1):6466. Epub 2021 Mar 19.

Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.

Smoking is one of the leading risk factors for cardiovascular diseases, including ischemic heart disease and hypertension. However, in acute myocardial infarction (AMI) patients, smoking has been associated with better clinical outcomes, a phenomenon termed the "smoker's paradox." Given the known detrimental effects of smoking on the cardiovascular system, it has been proposed that the beneficial effect of smoking on outcomes is due to age differences between smokers and non-smokers and is therefore a smoker's pseudoparadox. The aim of this study was to evaluate the association between smoking status and clinical outcomes in ST-segment elevation (STEMI) and non-STEMI (NSTEMI) patients treated by percutaneous coronary intervention (PCI), using a national multi-ethnic Asian registry. In unadjusted analyses, current smokers had better clinical outcomes following STEMI and NSTEMI. However, after adjusting for age, the protective effect of smoking was lost, confirming a smoker's pseudoparadox. Interestingly, although current smokers had increased risk for recurrent MI within 1 year after PCI in both STEMI and NSTEMI patients, there was no increase in mortality. In summary, we confirm the existence of a smoker's pseudoparadox in a multi-ethnic Asian cohort of STEMI and NSTEMI patients and report increased risk of recurrent MI, but not mortality, in smokers.
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http://dx.doi.org/10.1038/s41598-021-86003-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7979717PMC
March 2021

Risk factors for Coronavirus disease 2019 pneumonia after admission outside Wuhan, China.

Medicine (Baltimore) 2020 Nov;99(45):e22980

The central hospital of Shaoyang, NO.36, Road Qianyuan, Shaoyang, Hunan, China.

Coronavirus disease 2019 (COVID-19) has spread worldwide, causing significant stress on the medical system. We explored the risk factors for condition changes in COVID-19 pneumonia patients after admission.The patients diagnosed with COVID-19 pneumonia at 2 medical centers in Hunan Province were studied, and those whose conditions changed after admission were compared. Their clinical characteristics and experimental indicators were compared using SPSS software and R language to build a disease risk prediction model.Patients with condition changes after admission were older and had more blood cell abnormalities and impaired organ function (decreased albumin, elevated D-dimer) than normal patients. We found that age, neutrophil ratio, D-dimer, chest Computed tomograpgy (CT) changes, and glucocorticoid use were risk factors for COVID-19 pneumonia after admission.Elderly patients are more susceptible to disease changes after COVID-19 pneumonia; COVID-19 pneumonia patients who develop disease changes after admission have higher neutrophil ratios, increased D-dimer levels, chest imaging changes, and glucocorticoid usage. Additional research is needed.
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http://dx.doi.org/10.1097/MD.0000000000022980DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7647591PMC
November 2020

Quantification of effects of mean blood pressure and left ventricular mass on noninvasive fast fractional flow reserve.

Am J Physiol Heart Circ Physiol 2020 08 17;319(2):H360-H369. Epub 2020 Jul 17.

National Heart Centre Singapore, Singapore.

Proper inlet boundary conditions are essential for accurate computational fluid dynamics (CFD) modeling. We developed methodology to derive noninvasive FFR using CFD and computed tomography coronary angiography (CTCA) images. This study aims to assess the influence of brachial mean blood pressure (MBP) and total coronary inflow on FFR computation. Twenty-two patients underwent both CTCA and FFR measurements. Total coronary flow was computed from left ventricular mass (LVM) measured from CTCA. A total of 286 CFD simulations were run by varying MBP and LVM at 70, 80, 90, 100, 110, 120, and 130% of the measured values. FFR increased with incrementally higher input values of MBP: 0.78 ± 0.12, 0.80 ± 0.11, 0.82 ± 0.10, 0.84 ± 0.09, 0.85 ± 0.08, 0.86 ± 0.08, and 0.87 ± 0.07, respectively. Conversely, FFR decreased with incrementally higher inputs value of LVM: 0.86 ± 0.08, 0.85 ± 0.08, 0.84 ± 0.09, 0.84 ± 0.09, 0.83 ± 0.10, 0.83 ± 0.10, and 0.82 ± 0.10, respectively. Noninvasive FFR calculated using measured MBP and LVM on a total of 30 vessels was 0.84 ± 0.09 and correlated well with invasive FFR (0.83 ± 0.09) ( = 0.92, < 0.001). Positive association was observed between FFR and MBP input values (mmHg) and negative association between FFR and LVM values (g). Respective slopes were 0.0016 and -0.005, respectively, suggesting potential application of FFR in a clinical setting. Inaccurate MBP and LVM inputs differing from patient-specific values could result in misclassification of borderline ischemic lesions. While brachial mean blood pressure (MBP) and left ventricular mass (LVM) measured from CTCA are the two CFD simulation input parameters, their effects on noninvasive fractional flow reserve (FFR) have not been systematically investigated. We demonstrate that inaccurate MBP and LVM inputs differing from patient-specific values could result in misclassification of borderline ischemic lesions. This is important in the clinical application of noninvasive FFR in coronary artery disease diagnosis.
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http://dx.doi.org/10.1152/ajpheart.00135.2020DOI Listing
August 2020

Computed tomography coronary angiography - past, present and future.

Singapore Med J 2020 Mar;61(3):109-115

Department of Diagnostic Imaging, National University Hospital, Singapore.

Computed tomography coronary angiography (CTCA) is a robust and reliable non-invasive alternative imaging modality to invasive coronary angiography, which is the reference standard in evaluating the degree of coronary artery stenosis. CTCA has high negative predictive value and can confidently exclude significant coronary artery disease (CAD) in low to intermediate risk patients. Over the years, substantial effort has been made to reduce the radiation dose and increase the cost efficiency of CTCA. In this review, we present the evolution of computed tomography scanners in the context of coronary artery imaging as well as its clinical applications and limitations. We also highlight the future directions of CTCA as a one-stop non-invasive imaging modality for anatomic and functional assessment of CAD.
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http://dx.doi.org/10.11622/smedj.2020028DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7905109PMC
March 2020

Single Coronary Artery in a Young Male with Chest Pain.

JACC Case Rep 2020 May 20;2(5):721-722. Epub 2020 May 20.

National University Heart Centre, Singapore National University Health System, Singapore.

A young male presented to the hospital with chest pain. A coronary angiogram and a subsequent computed tomography coronary angiogram revealed a single coronary artery arising from the right coronary sinus which bifurcated into the right coronary artery and a large branch which supplies the left coronary artery territory. ().
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http://dx.doi.org/10.1016/j.jaccas.2020.03.027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8302055PMC
May 2020

Elevated Right Atrial Pressure Associated with Alteration of Left Ventricular Contractility and Ventricular-Arterial Coupling in Pulmonary Artery Hypertension.

Annu Int Conf IEEE Eng Med Biol Soc 2019 Jul;2019:820-823

Pulmonary artery hypertension (PAH) is a progressive disorder which leads to heart failure and death. Development of dilated right ventricle (RV), progressive RV dysfunction and increased right atrial (RA) pressure make the RV transition from a compensated to a decompensated phase and eventually leads to heart failure. However, the relationship between elevated RA pressure and left ventricular contractility and ventricular arterial coupling (VAC) has not been well studied. 36 patients were recruited and underwent both right heart catheterization (RHC) and cardiac magnetic resonance (CMR). Left ventricular (LV) pressure-volume loops were reconstructed from RHC and CMR. LV contractility was assessed by end-systolic elastance (E) using single-beat method and arterial elastance (E) was estimated as the ratio of end-systolic pressure and stroke volume (SV). The VAC was calculated as the ratio of E and E (i.e. E/E). The results demonstrated a nonlinear relationship between RA pressure and E, RA pressure and VAC. E increased when RA pressure increased to 7 mmHg and then decreased when RA pressure exceeded 7 mmHg. E were 2.79 ± 1.61 mmHg/ml, 4.27 ±1 33 mmHg/ml, 2.69 ± 0.89 mmHg/ml and 2.36± 1.10 mmHg/ml at ascending quartiles of RA pressure, respectively (quartile 1: RAP≤5 mmHg; quartile 2: 5<; RAP≤7 mmHg; quartile 3: 7<; RAP 10 mmHg and quartile 4: RAP>10 mmHg). Similarly, VAC were 1.36 ± 0.61, 1.93±0.86, 1.16 ± 0.55 and 0.95± 0.27 the four quartiles (both ANOVA P <; 0.05). We found that there was a nonlinear relationship between RA pressure and LV contractility, and between RA pressure and ventricular-arterial coupling. A cut-off value of 7 mmHg of RAP may indicate a decompensated LV hemodynamics.
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http://dx.doi.org/10.1109/EMBC.2019.8856814DOI Listing
July 2019

Magnetic resonance imaging of dilated cardiomyopathy: prognostic benefit of identifying late gadolinium enhancement in Asian patients.

Singapore Med J 2021 Jul 10;62(7):347-352. Epub 2019 Dec 10.

Department of Cardiology, National University Heart Centre Singapore, Singapore.

Introduction: Risk stratification in dilated cardiomyopathy (DCM) is imprecise, relying largely on echocardiographic left ventricular ejection fraction (LVEF) and severity of heart failure symptoms. Adverse cardiovascular events are increased by the presence of myocardial scarring. Late gadolinium enhancement (LGE) on cardiovascular magnetic resonance (CMR) imaging is the gold standard for identifying myocardial scars. We examined the association between LGE on CMR imaging and adverse clinical outcomes during long-term follow-up of Asian patients with DCM.

Methods: Consecutive patients with DCM undergoing CMR imaging at a single Asian academic medical centre between 2005 and 2015 were recruited. Clinical outcomes were tracked using comprehensive electronic medical records and mortality was determined by cross-linkages with national registries. Presence and distribution of LGE on CMR imaging were determined by investigators blinded to patient outcomes. Primary endpoint was a composite of heart failure hospitalisations, appropriate implantable cardioverter-defibrillator shocks and cardiovascular mortality.

Results: Of 86 patients, 64.0% had LGE (80.2% male; mean LVEF 30.1% ± 12.7%). Mid-wall fibrosis (71.7%) was the most common pattern of LGE distribution. Over a mean follow-up period of 4.9 ± 3.2 years, 19 (34.5%) patients with LGE reached the composite endpoint compared to 4 (12.9%) patients without LGE (p = 0.01). Presence of LGE, but not echocardiographic LVEF, independently predicted the primary endpoint (hazard ratio 4.15 [95% confidence interval 1.28-13.50]; p = 0.02).

Conclusion: LGE presence independently predicted adverse clinical events in Asian patients with DCM. Routine use of CMR imaging to characterise the myocardial substrate is recommended for enhanced risk stratification and should strongly influence clinical management.
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http://dx.doi.org/10.11622/smedj.2019166DOI Listing
July 2021

Combining Circulating MicroRNA and NT-proBNP to Detect and Categorize Heart Failure Subtypes.

J Am Coll Cardiol 2019 03;73(11):1300-1313

Cardiovascular Research Institute, National University Health System, Singapore; Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Cardiac Department, National University Health System, Singapore; Christchurch Heart Institute, University of Otago, Christchurch, New Zealand. Electronic address:

Background: Clinicians need improved tools to better identify nonacute heart failure with preserved ejection fraction (HFpEF).

Objectives: The purpose of this study was to derive and validate circulating microRNA signatures for nonacute heart failure (HF).

Methods: Discovery and validation cohorts (N = 1,710), comprised 903 HF and 807 non-HF patients from Singapore and New Zealand (NZ). MicroRNA biomarker panel discovery in a Singapore cohort (n = 546) was independently validated in a second Singapore cohort (Validation 1; n = 448) and a NZ cohort (Validation 2; n = 716).

Results: In discovery, an 8-microRNA panel identified HF with an area under the curve (AUC) 0.96, specificity 0.88, and accuracy 0.89. Corresponding metrics were 0.88, 0.66, and 0.77 in Validation 1, and 0.87, 0.58, and 0.74 in Validation 2. Combining microRNA panels with N-terminal pro-B-type natriuretic peptide (NT-proBNP) clearly improved specificity and accuracy from AUC 0.96, specificity 0.91, and accuracy 0.90 for NT-proBNP alone to corresponding metrics of 0.99, 0.99, and 0.93 in the discovery and 0.97, 0.96, and 0.93 in Validation 1. The 8-microRNA discovery panel distinguished HFpEF from HF with reduced ejection fraction with AUC 0.81, specificity 0.66, and accuracy 0.72. Corresponding metrics were 0.65, 0.41, and 0.56 in Validation 1 and 0.65, 0.41, and 0.62 in Validation 2. For phenotype categorization, combined markers achieved AUC 0.87, specificity 0.75, and accuracy 0.77 in the discovery with corresponding metrics of 0.74, 0.59, and 0.67 in Validation 1 and 0.72, 0.52, and 0.68 in Validation 2, as compared with NT-proBNP alone of AUC 0.71, specificity 0.46, and accuracy 0.62 in the discovery; with corresponding metrics of 0.72, 0.44, and 0.57 in Validation 1 and 0.69, 0.48, and 0.66 in Validation 2. Accordingly, false negative (FN) (81% Singapore and all NZ FN cases were HFpEF) as classified by a guideline-endorsed NT-proBNP ruleout threshold, were correctly reclassified by the 8-microRNA panel in the majority (72% and 88% of FN in Singapore and NZ, respectively) of cases.

Conclusions: Multi-microRNA panels in combination with NT-proBNP are highly discriminatory and improved specificity and accuracy in identifying nonacute HF. These findings suggest potential utility in the identification of nonacute HF, where clinical assessment, imaging, and NT-proBNP may not be definitive, especially in HFpEF.
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http://dx.doi.org/10.1016/j.jacc.2018.11.060DOI Listing
March 2019

Prediction of Survival in Asian Patients Hospitalized With Heart Failure: Validation of the OPTIMIZE-HF Risk Score.

J Card Fail 2019 Jul 26;25(7):571-575. Epub 2019 Feb 26.

Department of Cardiology, National Heart Centre Singapore, Singapore; Duke-NUS Medical School, Singapore.

Background: Risk scores predicting in-patient mortality in heart failure patients have not been designed specifically for Asian patients. We aimed to validate and recalibrate the OPTIMIZE-HF risk model for in-hospital mortality in a multiethnic Asian population hospitalized for heart failure.

Methods And Results: Data from the Singapore Cardiac Databank Heart Failure on patients admitted for heart failure from January 1, 2008, to December 31, 2013, were included. The primary outcome studied was in-hospital mortality. Two models were compared: the original OPTIMIZE-HF risk model and a modified OPTIMIZE-HF risk model (similar variables but with coefficients derived from our cohort). A total of 15,219 patients were included. The overall in-hospital mortality was 1.88% (n = 286). The original model had a C-statistic of 0.739 (95% CI 0.708-0.770) with a good match between predicted and observed mortality rates (Hosmer-Lemeshow statistic 13.8; P = .086). The modified model had a C-statistic of 0.741 (95% CI 0.709-0.773) but a significant difference between predicted and observed mortality rates (Hosmer-Lemeshow statistic 17.2; P = .029). The modified model tended to underestimate risk at the extremes (lowest and highest ends) of risk.

Conclusions: We provide the first independent validation of the OPTIMIZE-HF risk score in an Asian population. This risk model has been shown to perform reliably in our Asian cohort and will potentially provide clinicians with a useful tool to identify high-risk heart failure patients for more intensive management.
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http://dx.doi.org/10.1016/j.cardfail.2019.02.016DOI Listing
July 2019

Multimodality Cardiac Imaging in the Evaluation of a Patient with Near-Fatal Arrhythmia.

Ann Acad Med Singap 2019 Jan;48(1):39-41

Department of Medicine, National University Health System, Singapore.

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January 2019

Defining a 'frequent admitter' phenotype among patients with repeat heart failure admissions.

Eur J Heart Fail 2019 03 13;21(3):311-318. Epub 2018 Dec 13.

National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore.

Aims: We aimed to identify a 'frequent admitter' phenotype among patients admitted for acute decompensated heart failure (HF).

Methods And Results: We studied 10 363 patients in a population-based prospective HF registry (2008-2012), segregated into clusters based on their 3-year HF readmission frequency trajectories. Using receiver-operating characteristic analysis, we identified the index year readmission frequency threshold that most accurately predicts HF admission frequency clusters. Two clusters of HF patients were identified: a high frequency cluster (90.9%, mean 2.35 ± 3.68 admissions/year) and a low frequency cluster (9.1%, mean 0.50 ± 0.81 admission/year). An index year threshold of two admissions was optimal for distinguishing between clusters. Based on this threshold, 'frequent admitters', defined as patients with ≥ 2 HF admissions in the index year (n = 2587), were of younger age (68 ± 13 vs 69 ± 13 years), more often male (58% vs. 54%), smokers (38.4% vs. 34.4%) and had lower left ventricular ejection fraction (37 ± 17 vs. 41 ± 17%) compared to 'non-frequent admitters' (< 2 HF admissions in the index year; n = 7776) (all P < 0.001). Despite similar rates of advanced care utilization, frequent admitters had longer length of stay (median 4.3 vs. 4.0 days), higher annual inpatient costs (€ 7015 vs. € 2967) and higher all-cause mortality at 3 years compared to the non-frequent admitters (adjusted odds ratio 2.33, 95% confidence interval 2.11-2.58; P < 0.001).

Conclusion: 'Frequent admitters' have distinct clinical characteristics and worse outcomes compared to non-frequent admitters. This study may provide a means of anticipating the HF readmission burden and thereby aid in healthcare resource distribution relative to the HF admission frequency phenotype.
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http://dx.doi.org/10.1002/ejhf.1348DOI Listing
March 2019

Platelet inhibition to target reperfusion injury trial: Rationale and study design.

Clin Cardiol 2019 Jan 17;42(1):5-12. Epub 2018 Dec 17.

The Hatter Cardiovascular Institute, Institute of Cardiovascular Science, University College London, London, UK.

Background: In ST-segment elevation myocardial infarction (STEMI) patients treated with primary percutaneous coronary intervention (PPCI), current oral P2Y12 platelet inhibitors do not provide maximal platelet inhibition at the time of reperfusion. Furthermore, administration of cangrelor prior to reperfusion has been shown in pre-clinical studies to reduce myocardial infarct (MI) size. Therefore, we hypothesize that cangrelor administered prior to reperfusion in STEMI patients will reduce the incidence of microvascular obstruction (MVO) and limit MI size in STEMI patients treated with PPCI.

Methods: The platelet inhibition to target reperfusion injury (PITRI) trial, is a phase 2A, multi-center, double-blinded, randomized controlled trial, in which 210 STEMI patients will be randomized to receive either an intravenous (IV) bolus of cangrelor (30 μg/kg) followed by a 120-minute infusion (4 μg/kg/min) or matching saline placebo, initiated prior to reperfusion (NCT03102723).

Results: The study started in October 2017 and the anticipated end date would be July 2020. The primary end-point will be MI size quantified by cardiovascular magnetic resonance (CMR) on day 3 post-PPCI. Secondary endpoints will include markers of reperfusion, incidence of MVO, MI size, and adverse left ventricular remodeling at 6 months, and major adverse cardiac and cerebrovascular events.

Summary: The aim of the PITRI trial is to assess whether cangrelor administered prior to reperfusion would reduce acute MI size and MVO, as assessed by CMR.
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http://dx.doi.org/10.1002/clc.23110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6436500PMC
January 2019

Rhythmic chaos: irregularities of computer ECG diagnosis.

Singapore Med J 2017 09;58(9):516-520

Department of Cardiology, National University Health System, Singapore.

Diagnostic errors can occur when physicians rely solely on computer electrocardiogram interpretation. Cardiologists often receive referrals for computer misdiagnoses of atrial fibrillation. Patients may have been inappropriately anticoagulated for pseudo atrial fibrillation. Anticoagulation carries significant risks, and such errors may carry a high cost. Have we become overreliant on machines and technology? In this article, we illustrate three such cases and briefly discuss how we can reduce these errors.
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http://dx.doi.org/10.11622/smedj.2017088DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5605822PMC
September 2017

Thymosin Beta-4 Is Elevated in Women With Heart Failure With Preserved Ejection Fraction.

J Am Heart Assoc 2017 Jun 13;6(6). Epub 2017 Jun 13.

Cardiovascular Research Institute, National University Health System, Singapore

Background: Thymosin beta-4 (TB4) is an X-linked gene product with cardioprotective properties. Little is known about plasma concentration of TB4 in heart failure (HF), and its relationship with other cardiovascular biomarkers. We sought to evaluate circulating TB4 in HF patients with preserved (HFpEF) or reduced (HFrEF) ejection fraction compared to non-HF controls.

Methods And Results: TB4 was measured using a liquid chromatography and mass spectrometry assay in age- and sex-matched HFpEF (n=219), HFrEF (n=219) patients, and controls (n=219) from a prospective nationwide study. Additionally, a 92-marker multiplex proximity extension assay was measured to identify biomarker covariates. Compared with controls, plasma TB4 was elevated in HFpEF (985 [421-1723] ng/mL versus 1401 [720-2379] ng/mL, <0.001), but not in HFrEF (1106 [556-1955] ng/mL, =0.642). Stratifying by sex, only women (1623 [1040-2625] ng/mL versus 942 [386-1891] ng/mL, <0.001), but not men (1238.5 [586-1967] ng/mL versus 1004 [451-1538] ng/mL, =1.0), had significantly elevated TB4 in the setting of HFpEF. Adjusted for New York Heart Association class, N-terminal pro B-type natriuretic peptide, age, and myocardial infarction, hazard ratio to all-cause mortality is significantly higher in women with elevated TB4 (1.668, =0.036), but not in men (0.791, =0.456) with HF. TB4 is strongly correlated with a cluster of 7 markers from the proximity extension assay panel, which are either X-linked, regulated by sex hormones, or involved with NF-κB signaling.

Conclusions: We show that plasma TB4 is elevated in women with HFpEF and has prognostic information. Because TB4 can preserve EF in animal studies of cardiac injury, the relation of endogenous, circulating TB4 to X chromosome biology and differential outcomes in female heart disease warrants further study.
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http://dx.doi.org/10.1161/JAHA.117.005586DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5669175PMC
June 2017

Growth differentiation factor 15 in heart failure with preserved vs. reduced ejection fraction.

Eur J Heart Fail 2016 Jan 25;18(1):81-8. Epub 2015 Oct 25.

Cardiovascular Research Institute, National University of Singapore, Singapore.

Aim: Growth differentiation factor 15 (GDF15) is a cytokine highly expressed in states of inflammatory stress. We aimed to study the clinical correlates and prognostic significance of plasma GDF15 in heart failure with preserved ejection fraction (HFpEF) vs. reduced ejection fraction(HFrEF), compared with N-terminal pro-brain natriuretic peptide (NT-proBNP), an indicator of haemodynamic wall stress.

Methods: Plasma GDF15 and NT-proBNP were prospectively measured in 916 consecutive patients with HFrEF (EF <50%; n = 730) and HFpEF (EF ≥50%; n = 186), and measured again at 6 months in 488 patients. Patients were followed up for a composite outcome of death or first HF rehospitalization.

Results: Median GDF15baseline values were similarly elevated in HFpEF [2862 (1812 represent the 25th percentile and 4176 represent the 75th percentile) ng/L] and HFrEF [2517 (1555, 4030) ng/L] (P = 0.184), whereas NT-proBNP was significantly lower in HFpEF than HFrEF (1119 ng/L vs. 2335 ng/L, P < 0.001). Independent correlates of GDF15baseline were age, systolic blood pressure, New York Heart Association (NYHA) class, diabetes, atrial fibrillation, sodium, haemoglobin, creatinine, diuretic therapy, high sensitivity troponin T (hsTnT) and NT-proBNP (all P < 0.05). During a median follow-up of 23 months, there were 379 events (307 HFrEF, 72 HFpEF). GDF15 remained a significant independent predictor for composite outcome even after adjusting for important clinical predictors including hsTnT and NT-proBNP (adjusted hazard ratio 1.76 per 1 Ln U, 95% confidence interval 1.39-2.21; P < 0.001), regardless of HF group (Pinteraction  = 0.275). GDF15baseline provided incremental prognostic value when added to clinical predictors, hsTnT and NT-proBNP (area under receiver operating characteristic curve increased from 0.720 to 0.740, P < 0.019), with a net reclassification improvement of 0.183 (P = 0.004). Patients with ≥20% GDF156months increase had higher risk for composite outcome (adjusted hazard ratio 1.68, 95% confidence interval 1.15-2.45; P = 0.007) compared with those with GDF156months within ± 20% of baseline.

Conclusions: The similarly elevated levels and independent prognostic utility of GDF15 in HFrEF and HFpEF suggest that beyond haemodynamic stress (NT-proBNP), inflammatory injury (GDF15) may play an important role in both HF syndromes.
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http://dx.doi.org/10.1002/ejhf.431DOI Listing
January 2016

Relationship between ADH2 Arg47His variation and hepatocellular carcinoma susceptibility: a meta analysis.

Int J Clin Exp Med 2015 15;8(6):9543-8. Epub 2015 Jun 15.

Clinical Oncology Department, Weifang People's Hospital Kuiwen District, Weifang, Shandong, China.

Background: To further investigate the relationship between ADH2 Arg47His variation and hepatocellular carcinoma (HCC) susceptibility through a meta-analysis.

Methods: The related articles were searched in PubMed, Embase and CNKI databases. And finally 518 cases and 607 controls were included in our meta-analysis Odds ratios (ORs) with 95% confidence intervals (95% CIs) were used to assess the relationship between ADH2 Arg47His variation and HCC risk. A fixed-effect model or a random-effect model was applied according to the between-study heterogeneity.

Results: Quantitative synthesis demonstrated that no significant association was found between ADH2 Arg47His variation and HCC susceptibility (His/His vs. Arg/Arg: OR=0.99, 95% CI=0.79-1.25; His/His + Arg/His vs. Arg/Arg: OR=1.01, 95% CI=0.86-1.20; His/His vs. Arg/Arg + Arg/His: OR=0.90, 95% CI=0.74-1.11; His vs. Arg: OR=0.98, 95% CI=0.86-1.11; Arg/His vs. Arg/Arg: OR=1.05, 95% CI=0.82-1.34).

Conclusion: Our analysis showed that ADH2 Arg47His vvariation may not be associated with HCC susceptibility.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4538084PMC
August 2015

Precursor Routes to Complex Ternary Intermetallics: Single-Crystal and Microcrystalline Preparation of Clathrate-I Na8Al8Si38 from NaSi + NaAlSi.

Inorg Chem 2015 Jun 18;54(11):5316-21. Epub 2015 May 18.

†Department of Physics, University of South Florida, Tampa, Florida 33620, United States.

Single crystals of the ternary clathrate-I Na8Al8Si38 were synthesized by kinetically controlled thermal decomposition (KCTD), and microcrystalline Na8Al8Si38 was synthesized by spark plasma sintering (SPS) using a NaSi + NaAlSi mixture as the precursor. Na8AlxSi46-x compositions with x ≤ 8 were also synthesized by SPS from precursor mixtures of different ratios. The crystal structure of Na8Al8Si38 was investigated using both Rietveld and single-crystal refinements. Temperature-dependent transport and UV/vis measurements were employed in the characterization of Na8Al8Si38, with diffuse-reflectance measurement indicating an indirect optical gap of 0.64 eV. Our results indicate that, when more than one precursor is used, both SPS and KCTD are effective methods for the synthesis of multinary inorganic phases that are not easily accessible by traditional solid-state synthesis or crystal growth techniques.
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http://dx.doi.org/10.1021/acs.inorgchem.5b00348DOI Listing
June 2015

Circulating microRNAs in heart failure with reduced and preserved left ventricular ejection fraction.

Eur J Heart Fail 2015 Apr 23;17(4):393-404. Epub 2015 Jan 23.

Cardiovascular Research Institute, Singapore; Department of Medicine, Singapore.

Aim: The potential diagnostic utility of circulating microRNAs in heart failure (HF) or in distinguishing HF with reduced vs. preserved left ventricular ejection fraction (HFREF and HFPEF, respectively) is unclear. We sought to identify microRNAs suitable for diagnosis of HF and for distinguishing both HFREF and HFPEF from non-HF controls and HFREF from HFPEF.

Methods And Results: MicroRNA profiling performed on whole blood and corresponding plasma samples of 28 controls, 39 HFREF and 19 HFPEF identified 344 microRNAs to be dysregulated among the three groups. Further analysis using an independent cohort of 30 controls, 30 HFREF and 30 HFPEF, presented 12 microRNAs with diagnostic potential for one or both HF phenotypes. Of these, miR-1233, -183-3p, -190a, -193b-3p, -193b-5p, -211-5p, -494, and -671-5p distinguished HF from controls. Altered levels of miR-125a-5p, -183-3p, -193b-3p, -211-5p, -494, -638, and -671-5p were found in HFREF while levels of miR-1233, -183-3p, -190a, -193b-3p, -193b-5p, and -545-5p distinguished HFPEF from controls. Four microRNAs (miR-125a-5p, -190a, -550a-5p, and -638) distinguished HFREF from HFPEF. Selective microRNA panels showed stronger discriminative power than N-terminal pro-brain natriuretic peptide (NT-proBNP). In addition, individual or multiple microRNAs used in combination with NT-proBNP increased NT-proBNP's discriminative performance, achieving perfect intergroup distinction. Pathway analysis revealed that the altered microRNAs expression was associated with several mechanisms of potential significance in HF.

Conclusions: We report specific microRNAs as potential biomarkers in distinguishing HF from non-HF controls and in differentiating between HFREF and HFPEF.
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http://dx.doi.org/10.1002/ejhf.223DOI Listing
April 2015

A study protocol of a randomized controlled trial examining the efficacy of a symptom self-management programme for people with acute myocardial infarction.

J Adv Nurs 2015 Jun 19;71(6):1299-309. Epub 2014 Dec 19.

Alice Lee Centre for Nursing Studies, National University of Singapore, Singapore.

Aim: To report a study protocol of a randomized controlled trial examining if a symptom self-management programme helps patients with acute myocardial infarction self-manage their physical and psychological symptoms.

Background: In addition to physical conditions, people with acute myocardial infarction often experience psychological symptoms. However, there is limited empirical evidence on how to help individuals self-manage these psychological symptoms.

Design: A single-blinded, randomized controlled trial is proposed.

Methods: A convenience sample of 90 will be recruited. Eligible participants will be adult patients with acute myocardial infarction hospitalized at a tertiary hospital in Singapore. Participants will be randomly assigned to one of the three treatment groups: Intervention 1 and standard care (n = 30), Intervention 2 and standard care (n = 30) and standard care alone (n = 30). Data will be collected by self-reported questionnaires, physiological measures and open-ended questions. Quantitative data will be analysed by descriptive statistics, t-test, analysis of covariance and repeated measures analysis of variance. Open-ended questions will be analysed by content analysis.

Discussion: This study will identify a potentially efficacious symptom self-management programme for patients with acute myocardial infarction. If the efficacy of the programme is demonstrated, the programme can be integrated into hospital services to improve patient care. A new teaching method (virtual reality-based teaching) and new teaching materials (virtual reality videos and relaxation videos) derived from this study can be offered to patients. Future research with larger samples and multi-centre recruitment can be undertaken to further test the efficacy of the interventions.
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http://dx.doi.org/10.1111/jan.12594DOI Listing
June 2015

Iron deficiency in a multi-ethnic Asian population with and without heart failure: prevalence, clinical correlates, functional significance and prognosis.

Eur J Heart Fail 2014 Oct 11;16(10):1125-32. Epub 2014 Sep 11.

National University Heart Centre Singapore, National University Health System, Tower Block Level 9, 1E Kent Ridge Road, Singapore 119228, Singapore.

Aims: Current heart failure (HF) guidelines highlight the importance of iron deficiency (ID) in HF. Whether HF itself or age-related comorbidities contribute to ID is uncertain, and previous data were limited to Western populations. We aimed to study the prevalence, clinical correlates, functional significance and prognosis of ID in HF patients, compared with community-based controls in a multi-ethnic Southeast Asian population.

Methods And Results: Iron status was assessed in 751 HF patients (age 62.0 ± 12.2 years, 75.5% men, 64.7% Chinese, 23.9% Malay, 10.2% Indian) and 601 controls (age 56.9 ± 10.4 years, 49.8% men, 70.9% Chinese, 21.5% Malay, 7.2% Indian). ID, defined as ferritin <100 µg/L or ferritin 100-300 µg/L and transferrin saturation (Tsat) <20%, was present in 39.3% of controls and 61.4% of HF [odds ratio (OR) 3.5, 95% confidence interval (CI) 2.5-4.9, adjusting for clinical covariates]. Independent correlates of ID in HF were Indian ethnicity (OR 2.4 vs. Chinese, 95% CI 1.2-5.0), female gender (OR 2.8, 95% CI 1.7-4.8), larger body mass index (OR 1.05/unit increase, 95% CI 1.01-1.1) and decreased left ventricular ejection fraction (OR 1.03/unit decrease, 95% CI 1.01-1.04). In a subset of 48 HF patients undergoing cardiopulmonary exercise testing, Tsat correlated with peak oxygen consumption (ρ = 0.53, P < 0.01), independent of baseline characteristics. The HF patients with Tsat <20% as well as anaemia showed the poorest event-free survival after adjusting for clinical covariates.

Conclusions: ID was highly prevalent and independently related to functional capacity and outcomes in our cohort. These findings suggest a pathophysiological role of ID in HF and support its importance as a therapeutic target in Southeast Asian patients with HF.
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http://dx.doi.org/10.1002/ejhf.161DOI Listing
October 2014

Automatic 4D reconstruction of patient-specific cardiac mesh with 1-to-1 vertex correspondence from segmented contours lines.

PLoS One 2014 17;9(4):e93747. Epub 2014 Apr 17.

Cardiac Department, National University Heart Center, National University Health System, Singapore, Singapore.

We propose an automatic algorithm for the reconstruction of patient-specific cardiac mesh models with 1-to-1 vertex correspondence. In this framework, a series of 3D meshes depicting the endocardial surface of the heart at each time step is constructed, based on a set of border delineated magnetic resonance imaging (MRI) data of the whole cardiac cycle. The key contribution in this work involves a novel reconstruction technique to generate a 4D (i.e., spatial-temporal) model of the heart with 1-to-1 vertex mapping throughout the time frames. The reconstructed 3D model from the first time step is used as a base template model and then deformed to fit the segmented contours from the subsequent time steps. A method to determine a tree-based connectivity relationship is proposed to ensure robust mapping during mesh deformation. The novel feature is the ability to handle intra- and inter-frame 2D topology changes of the contours, which manifests as a series of merging and splitting of contours when the images are viewed either in a spatial or temporal sequence. Our algorithm has been tested on five acquisitions of cardiac MRI and can successfully reconstruct the full 4D heart model in around 30 minutes per subject. The generated 4D heart model conforms very well with the input segmented contours and the mesh element shape is of reasonably good quality. The work is important in the support of downstream computational simulation activities.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0093747PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3990569PMC
January 2015
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