Publications by authors named "Naeem Merchant"

46 Publications

Right ventricular insertion site fibrosis in a dilated cardiomyopathy referral population: phenotypic associations and value for the prediction of heart failure admission or death.

J Cardiovasc Magn Reson 2021 06 17;23(1):79. Epub 2021 Jun 17.

Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute of Alberta, University of Calgary, #0700, SSB, Foothills Medical Centre, 1403-29th St. NW, Calgary, AB, T2N2T9, Canada.

Background: Dilated cardiomyopathy (DCM) is increasingly recognized as a heterogenous disease with distinct phenotypes on late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging. While mid-wall striae (MWS) fibrosis is a widely recognized phenotypic risk marker, other fibrosis patterns are prevalent but poorly defined. Right ventricular (RV) insertion (RVI) site fibrosis is commonly seen, but without objective criteria has been considered a non-specific finding. In this study we developed objective criteria for RVI fibrosis and studied its clinical relevance in a large cohort of patients with DCM.

Methods: We prospectively enrolled 645 DCM patients referred for LGE-CMR. All underwent standardized imaging protocols and baseline health evaluations. LGE images were blindly scored using objective criteria, inclusive of RVI site and MWS fibrosis. Associations between LGE patterns and CMR-based markers of adverse chamber remodeling were evaluated. Independent associations of LGE fibrosis patterns with the primary composite clinical outcome of heart failure admission or death were determined by multivariable analysis.

Results: The mean age was 56 ± 14 (28% female) with a mean left ventricular (LV) ejection fraction (LVEF) of 37%. At a median of 1061 days, 129 patients (20%) experienced the primary outcome. Any abnormal LGE was present in 306 patients (47%), inclusive of 274 (42%) meeting criteria for RVI site fibrosis and 167 (26%) for MWS fibrosis. All with MWS fibrosis showed RVI site fibrosis. Solitary RVI site fibrosis was associated with higher bi-ventricular volumes [LV end-systolic volume index (78 ± 39 vs. 66 ± 33 ml/m, p = 0.01), RV end-diastolic volume index (94 ± 28 vs. 84 ± 22 ml/m (p < 0.01), RV end-systolic volume index (56 ± 26 vs. 45 ± 17 ml/m, p < 0.01)], lower bi-ventricular function [LVEF 35 ± 12 vs. 39 ± 10% (p < 0.01), RV ejection fraction (RVEF) 43 ± 12 vs. 48 ± 10% (p < 0.01)], and higher extracellular volume (ECV). Patient with solitary RVI site fibrosis experienced a non-significant 1.4-fold risk of the primary outcome, increasing to a significant 2.6-fold risk when accompanied by MWS fibrosis.

Conclusions: RVI site fibrosis in the absence of MWS fibrosis is associated with bi-ventricular remodelling and intermediate risk of heart failure admission or death. Our study findings suggest RVI site fibrosis to be pre-requisite for the incremental development of MWS fibrosis, a more advanced phenotype associated with greater LV remodeling and risk of clinical events.
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http://dx.doi.org/10.1186/s12968-021-00761-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8210339PMC
June 2021

Right Ventricular Ejection Fraction for the Prediction of Major Adverse Cardiovascular and Heart Failure-Related Events: A Cardiac MRI Based Study of 7131 Patients With Known or Suspected Cardiovascular Disease.

Circ Cardiovasc Imaging 2021 03 16;14(3):e011337. Epub 2021 Mar 16.

Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute of Alberta (Y.P., L.Y.L., S.D., Y.M., A.C., A.S., J.F., S.R., R.S., M.S., C.P.L., A.G.H., B.H., N.M., M.B., N.F., J.A.W.), Cumming School of Medicine, University of Calgary, Canada.

Background: There is increasing evidence that right ventricular ejection fraction (RVEF) may provide incremental value to left ventricular (LV) ejection fraction for the prediction of major adverse cardiovascular events. To date, generalizable utility for RVEF quantification in patients with cardiovascular disease has not been established. Using a large prospective clinical outcomes registry, we investigated the prognostic value of RVEF for the prediction of major adverse cardiovascular events- and heart failure-related outcomes.

Methods: Seven thousand one hundred thirty-one consecutive patients with known or suspected cardiovascular disease undergoing cardiovascular magnetic resonance imaging were prospectively enrolled. Multichamber volumetric quantification was performed by standardized operational procedures. Patients were followed for the primary composite outcome of all-cause death, survived cardiac arrest, admission for heart failure, need for transplantation or LV assist device, acute coronary syndrome, need for revascularization, stroke, or transient ischemic attack. A secondary, heart failure focused outcome of heart failure admission, need for transplantation/LV assist device or death was also studied.

Results: Mean age was 54±15 years. The mean LV ejection fraction was 55±14% (range 6%-90%) with a mean RVEF of 54±10% (range 9%-87%). At a median follow-up of 908 days, 870 (12%) patients experienced the primary composite outcome and 524 (7%) the secondary outcome. Each 10% drop in RVEF was associated with a 1.3-fold increased risk of the primary outcome (<0.001) and 1.5-fold increased risk of the secondary outcome (<0.001). RVEF was an independent predictor following comprehensive covariate adjustment, inclusive of LV ejection fraction. Patients with an RVEF<40% experienced a 3.1-fold risk of the primary outcome (<0.001) with a 1-year cumulative event rate of 22% versus 7% above this cutoff.

Conclusions: RVEF is a powerful and independent predictor of major adverse cardiac events with broad generalizability across patients with known or suspected cardiovascular disease. These findings support migration towards biventricular phenotyping for the classification of risk in clinical practice. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04367220.
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http://dx.doi.org/10.1161/CIRCIMAGING.120.011337DOI Listing
March 2021

Neural-Network-Based Diagnosis Using 3-Dimensional Myocardial Architecture and Deformation: Demonstration for the Differentiation of Hypertrophic Cardiomyopathy.

Front Cardiovasc Med 2020 11;7:584727. Epub 2020 Nov 11.

Stephenson Cardiac Imaging Center, Calgary, AB, Canada.

The diagnosis of cardiomyopathy states may benefit from machine-learning (ML) based approaches, particularly to distinguish those states with similar phenotypic characteristics. Three-dimensional myocardial deformation analysis (3D-MDA) has been validated to provide standardized descriptors of myocardial architecture and deformation, and may therefore offer appropriate features for the training of ML-based diagnostic tools. We aimed to assess the feasibility of automated disease diagnosis using a neural network trained using 3D-MDA to discriminate hypertrophic cardiomyopathy (HCM) from its mimic states: cardiac amyloidosis (CA), Anderson-Fabry disease (AFD), and hypertensive cardiomyopathy (HTNcm). 3D-MDA data from 163 patients (mean age 53.1 ± 14.8 years; 68 females) with left ventricular hypertrophy (LVH) of known etiology was provided. Source imaging data was from cardiac magnetic resonance (CMR). Clinical diagnoses were as follows: 85 HCM, 30 HTNcm, 30 AFD, and 18 CA. A fully-connected-layer feed-forward neural was trained to distinguish HCM vs. other mimic states. Diagnostic performance was compared to threshold-based assessments of volumetric and strain-based CMR markers, in addition to baseline clinical patient characteristics. Threshold-based measures provided modest performance, the greatest area under the curve (AUC) being 0.70. Global strain parameters exhibited reduced performance, with AUC under 0.64. A neural network trained exclusively from 3D-MDA data achieved an AUC of 0.94 (sensitivity 0.92, specificity 0.90) when performing the same task. This study demonstrates that ML-based diagnosis of cardiomyopathy states performed exclusively from 3D-MDA is feasible and can distinguish HCM from mimic disease states. These findings suggest strong potential for computer-assisted diagnosis in clinical practice.
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http://dx.doi.org/10.3389/fcvm.2020.584727DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7693650PMC
November 2020

Rapid Response to Cytokine Storm Inhibition Using Anakinra in a Patient With COVID-19 Myocarditis.

CJC Open 2021 Feb 12;3(2):210-213. Epub 2020 Oct 12.

Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.

A 62-year-old woman with coronavirus disease 2019 developed acute respiratory failure and cardiogenic shock in the setting of a systemic hyperinflammatory state and apparent ST-elevation myocardial infarction. Cardiac magnetic resonance imaging showed fulminant acute myocarditis with severe left ventricular dysfunction. Treatment with the recombinant interleukin-1 receptor antagonist anakinra and dexamethasone resulted in rapid clinical improvement, reduction in serum inflammatory markers, and a marked recovery in cardiac magnetic resonance--based markers of inflammation and contractile dysfunction. The patient was subsequently discharged from the hospital. Emerging evidence supports use of anti-inflammatory therapies, including anakinra and dexamethasone, in severe cases of coronavirus disease 2019.
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http://dx.doi.org/10.1016/j.cjco.2020.10.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7550126PMC
February 2021

3-Dimensional regional and global strain abnormalities in hypertrophic cardiomyopathy.

Int J Cardiovasc Imaging 2019 Oct 29;35(10):1913-1924. Epub 2019 May 29.

Division of Cardiology, Department of Cardiac Sciences, Stephenson Cardiac Imaging Centre, University of Calgary, Calgary, Canada.

Hypertrophic cardiomyopathy (HCM) is characterized by myocardial disarray, hypertrophy, and fibrosis. Reduced global longitudinal strain and presence of late gadolinium enhancement (LGE) by cardiac magnetic resonance imaging (CMR) have been associated with an adverse prognosis. This study evaluated 3D principal and conventional strain characteristics of non-enhanced myocardium in patients with HCM. 3D principal and conventional strain analysis was conducted in 51 HCM patients and 38 healthy controls. Principal strain was reduced within the non-enhanced myocardium of HCM as compared with controls (maximum principal: 51.5 ± 23.7 vs. 75.1 ± 21.4%, P < 0.0001; minimum principal: - 18.4 ± 4.0 vs. - 20.1 ± 2.9%, P < 0.05). Principal strain within the non-enhanced myocardium was incrementally reduced in HCM patients with extensive global LGE ( ≥ 15%) (maximum principal: 41.6 ± 17.5 vs. 56.9 ± 25.9%, P < 0.05; minimum principal: - 16.9 ± 3.9 vs. - 19.1 ± 4.0%, P = 0.1), as was longitudinal ( - 10.5 ± 2.6 vs. - 12.7 ± 2.6%, P < 0.05) and circumferential strain ( - 11.0 ± 2.7 vs. - 14.0 ± 2.9%, P < 0.01). Principal strain within non-enhanced myocardium was significantly correlated with indexed LV mass (P < 0.0001), maximum (P = 0.0008), and mean wall thickness (P < 0.0001), but not LGE (P = 0.0841). In adjusted analysis, all strain measures within non-enhanced myocardium were independently associated with indexed LV mass (maximum principal: P = 0.0003; minimum principal: P = 0.0039; longitudinal: P = 0.0015; circumferential: P = 0.0002; radial: P = 0.0023). 3D principal strain of non-enhanced myocardium was significantly reduced in HCM patients as compared with controls, and was incrementally reduced among patients with more extensive global LGE. Comprehensive strain assessment may be considered in routine CMR assessment of HCM patients.
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http://dx.doi.org/10.1007/s10554-019-01631-8DOI Listing
October 2019

Intra-thoracic adiposity is associated with impaired contractile function in patients with coronary artery disease: a cardiovascular magnetic resonance imaging study.

Int J Cardiovasc Imaging 2019 Jan 4;35(1):121-131. Epub 2018 Aug 4.

Stephenson Cardiac Imaging Centre, Suite 0700 Foothills Medical Centre - 1403 29th St NW, Calgary, AB, T2N 2T9, Canada.

The influence of visceral adiposity on left ventricular remodeling following coronary artery disease (CAD)-related events has not been examined to date. Using magnetic resonance imaging (MRI) we explored intra-thoracic fat volume (ITFV) and strain-based markers of adverse remodeling in patients with CAD. Forty-seven patients with known CAD (25 with prior MI, 22 without prior MI) were studied. ITFV was quantified using previously validated imaging techniques. Myocardial strain was derived from cine MRI using a validated 3D feature-tracking (FT) software. Segmental LGE quantification was performed and was used to incrementally constrain strain analyses to non-infarcted (i.e. remote) segments. Remote myocardial strain was compared to the non-MI control cohort and was explored for associations with ITFV. Mean age was 57 ± 13 years with a mean BMI of 30.0 ± 6.2 kg/m (range 20.3-38.4 kg/m). Patients with versus without prior MI had similar demographics and BMI (29.4 ± 4.4 vs. 30.4 ± 7.9 kg/m, p = 0.62). Patients with prior MI had lower mean peak strain than non-MI patients (p = 0.02), consistent with remote tissue contractile dysfunction. Inverse associations were identified between ITFV and mean peak strain in both the MI group (circumferential: r = 0.43, p = 0.03; radial: - 0.41, p = 0.04; minimum principal: r = 0.41, p = 0.04; maximum principal: r = - 0.43, p = 0.03) and non-MI group (circumferential: r = 0.42, p = 0.05; minimum principal: r = 0.45, p = 0.03). In those with prior MI higher ITFV was associated with a greater reduction in remote tissue strain. ITFV is associated with contractile dysfunction in patients with CAD. This association is prominent in the post-MI setting suggesting relevant influence on remote tissue health following ischemic injury. Expanded study of intra-thoracic adiposity as a modulator of myocardial health in patients with CAD is warranted.
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http://dx.doi.org/10.1007/s10554-018-1430-1DOI Listing
January 2019

Three-dimensional thoracic aorta principal strain analysis from routine ECG-gated computerized tomography: feasibility in patients undergoing transcatheter aortic valve replacement.

BMC Cardiovasc Disord 2018 05 2;18(1):76. Epub 2018 May 2.

Division of Cardiology, Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, South Health Campus, 4448 Front Street SE, Calgary, Alberta, T3M 1M4, Canada.

Background: Functional impairment of the aorta is a recognized complication of aortic and aortic valve disease. Aortic strain measurement provides effective quantification of mechanical aortic function, and 3-dimenional (3D) approaches may be desirable for serial evaluation. Computerized tomographic angiography (CTA) is routinely performed for various clinical indications, and offers the unique potential to study 3D aortic deformation. We sought to investigate the feasibility of performing 3D aortic strain analysis in a candidate population of patients undergoing transcatheter aortic valve replacement (TAVR).

Methods: Twenty-one patients with severe aortic valve stenosis (AS) referred for TAVR underwent ECG-gated CTA and echocardiography. CTA images were analyzed using a 3D feature-tracking based technique to construct a dynamic aortic mesh model to perform peak principal strain amplitude (PPSA) analysis. Segmental strain values were correlated against clinical, hemodynamic and echocardiographic variables. Reproducibility analysis was performed.

Results: The mean patient age was 81±6 years. Mean left ventricular ejection fraction was 52±14%, aortic valve area (AVA) 0.6±0.3 cm and mean AS pressure gradient (MG) 44±11 mmHg. CTA-based 3D PPSA analysis was feasible in all subjects. Mean PPSA values for the global thoracic aorta, ascending aorta, aortic arch and descending aorta segments were 6.5±3.0, 10.2±6.0, 6.1±2.9 and 3.3±1.7%, respectively. 3D PSSA values demonstrated significantly more impairment with measures of worsening AS severity, including AVA and MG for the global thoracic aorta and ascending segment (p<0.001 for all). 3D PSSA was independently associated with AVA by multivariable modelling. Coefficients of variation for intra- and inter-observer variability were 5.8 and 7.2%, respectively.

Conclusions: Three-dimensional aortic PPSA analysis is clinically feasible from routine ECG-gated CTA. Appropriate reductions in PSSA were identified with increasing AS hemodynamic severity. Expanded study of 3D aortic PSSA for patients with various forms of aortic disease is warranted.
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http://dx.doi.org/10.1186/s12872-018-0818-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5932860PMC
May 2018

Objective criteria for septal fibrosis in non-ischemic dilated cardiomyopathy: validation for the prediction of future cardiovascular events.

J Cardiovasc Magn Reson 2016 Nov 14;18(1):82. Epub 2016 Nov 14.

Stephenson Cardiac Imaging Centre, Libin Cardiovascular Institute of Alberta, University of Calgary, #0700, SSB, Foothills Medical Centre, 1403-29th St. NW, Calgary, AB, T2N2T9, Canada.

Background: Expert subjective reporting of mid-wall septal fibrosis on late gadolinium enhancement (LGE) images has been shown to predict major cardiovascular outcomes in patients with non-ischemic dilated cardiomyopathy (NIDCM). This study aims to establish objective criteria for non-experts to report clinically relevant septal fibrosis and compare its performance by such readers versus experts for the prediction of cardiovascular events.

Methods: LGE cardiovascular magnetic resonance (CMR) was performed in 118 consecutive patients with NIDCM (mean age 57 ± 14, 42 % female) and the presence of septal fibrosis scored by expert readers. CMR-naive readers performed signal threshold-based LGE quantification by referencing mean values of remote tissue and applying these to a pre-defined anatomic region to measure septal fibrosis. All patients were followed for the primary composite outcome of cardiac mortality or appropriate implantable cardioverter-defibrillator (ICD) therapy.

Results: The mean LVEF was 32 ± 12 %. At a median follow-up of 1.9 years, 20 patients (17 %) experienced a primary composite outcome. Expert visual scoring identified 55 patients with septal fibrosis. Non-expert septal fibrosis quantification was highly reproducible and identified mean septal fibrosis burden for three measured thresholds as follows; 5SD: 2.9 ± 3.6 %, 3SD: 6.9 ± 6.3 %, and 2SD: 11.1 ± 7.5 % of the left ventricular (LV) mass, respectively. By ROC analysis, optimal thresholds for prediction of the primary outcome were; 5SD: 2.74 % (HR 8.7, p < 0.001), 3SD: 6.63 % (HR 5.7, p = 0.001) and 2SD: 10.15 % (HR 6.1, p = 0.001). By comparison, expert visual scoring provided a HR of 5.3 (p = 0.001). In adjusted analysis, objective quantification by a novice reader (>5SD threshold) was the strongest independent predictor of the primary outcome (HR 8.7) and provided improved risk reclassification beyond LVEF alone (NRI 0.54, 95 % CI 0.16-0.92, p = 0.005).

Conclusions: Novice readers were able to achieve superior risk prediction for future cardiovascular events versus experts using objective criteria for septal fibrosis in patients with NIDCM. Patients with a septal fibrosis burden >2.74 % of the LV mass (>5SD threshold) were at a 9-fold higher risk of cardiac death or appropriate ICD therapy versus those not meeting this criteria. As such, this study validates reproducible criteria applicable to all levels of expertise to identify NIDCM patients at high risk of future cardiovascular events.
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http://dx.doi.org/10.1186/s12968-016-0300-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5108079PMC
November 2016

Importance of Reference Muscle Selection in Quantitative Signal Intensity Analysis of T2-Weighted Images of Myocardial Edema Using a T2 Ratio Method.

Biomed Res Int 2015 21;2015:232649. Epub 2015 Jun 21.

CMR Centre, Montreal Heart Institute, University of Montreal, Montreal, QC, Canada H1T 1C8 ; Stephenson CMR Centre, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada T2N 2T9.

Objectives: The purpose of our study was to identify the suitability of various skeletal muscles as reference regions for calculating the T2 SI ratio for a semiautomated quantification of the extent of myocardial edema with T2-weighted images.

Methods: Thirty-four patients with acute myocardial infarction (MI) were enrolled. The extent of myocardial edema was determined by T2 SI ratio map, using 4 different muscles as reference: major and minor pectoralis, serratus anterior, teres minor-infraspinatus, and subscapularis. The size of myocardial edema as visually quantified was used as the standard of truth. The control group consisted of 15 patients with chronic MI. Intra- and interobserver variability were assessed.

Results: Due to poor image quality four patients were excluded from the analysis. In acute MI patients, serratus anterior muscle showed the strongest correlation with the visual analysis (r = 0.799; P < 0.001) and low inter- and intraobserver variability, while the other muscles resulted in a significant interobserver variability. In contrast, the use of other muscles as a reference led to overestimating edema size.

Conclusions: In acute MI patients, serratus anterior resulted to be the most reliable and reproducible muscle for measuring the extent of myocardial edema.
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http://dx.doi.org/10.1155/2015/232649DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4491384PMC
April 2016

Midterm results of endovascular stent grafts in the proximal aortic arch (zone 0): an imaging perspective.

Can J Cardiol 2015 Jun 25;31(6):731-7. Epub 2014 Dec 25.

Division of Cardiac Surgery, Libin Cardiovascular Institute, University of Calgary, Calgary, Alberta, Canada.

Background: Endovascular options to repair the arch and ascending aorta are rapidly evolving. Little is known about the durability of endovascular devices deployed at this location. This report describes a single-centre experience with the novel application of thoracic endovascular aortic repair (TEVAR) by examining clinical and radiological outcomes.

Methods: A retrospective review was performed for a cohort of patients undergoing TEVAR of the arch or ascending aorta, or both, at a single centre from November 2008-July 2012.

Results: Sixteen patients were included in the study, with mean imaging follow-up of 38 months (range, 15-72 months). Two complications at the proximal landing zone in the ascending aorta were identified: 1 endoleak and 1 infolding identified at 3 and 24 months postoperatively, respectively. Clinically, both these complications were attributed to the bird-beak configuration at the proximal landing zone site. At up to 72 months of follow-up, there were no cases of retrograde dissection of the native sinus of Valsalva. There were no cases of stent graft migration, graft fracture, open surgical reintervention for aortic pathologic conditions, or late mortality.

Conclusions: Early outcomes suggest that the current generation of thoracic aortic endografts can be placed in the complex anatomy of the ascending aorta and aortic arch without a high incidence of early graft fracture or migration. Future endeavors will need to focus on techniques to achieve optimal apposition with the curves of the ascending aorta. These findings are important as indications for endovascular aortic therapies expand to address proximal aortic pathologic conditions.
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http://dx.doi.org/10.1016/j.cjca.2014.12.023DOI Listing
June 2015

Cardiomyocyte apoptosis contributes to pathogenesis of cirrhotic cardiomyopathy in bile duct-ligated mice.

Clin Sci (Lond) 2014 Oct;127(8):519-26

*Liver Unit, University of Calgary, Calgary, Canada.

Cirrhotic cardiomyopathy is defined as systolic and diastolic dysfunctions, electrophysiological changes and macroscopic structural changes. However, the underlying mechanisms of this syndrome remain unclear. A possible role of myocardial apoptosis in the pathogenesis has not been previously examined. We hypothesized that dysregulation of apoptotic signalling participates in cardiac dysfunction in the cirrhotic heart. Therefore, we evaluated apoptotic pathways in the hearts of mice with chronic BDL (bile duct ligation). A cirrhotic cardiomyopathy model was induced by BDL in mice. Left ventricular geometry and volumes were evaluated by MRI. Intrinsic and extrinsic apoptotic pathways were evaluated by immunohistochemical staining and Western blot analysis. Fas-mediated apoptosis was inhibited by in vivo administration of an anti-FasL (Fas ligand) monoclonal antibody, and subsequently cardiac contractility was measured in isolated cardiomyocytes. BDL-mice showed significantly more PARP [poly(ADP-ribose) polymerase] staining than sham controls (18.2±11.4 compared with 6.7±5.3; P<0.05). Fas protein expression and PARP cleavage were activated, whereas FLIP (Fas-associated death domain-like interleukin 1β-converting enzyme-inhibitory protein) was decreased compared with sham controls. The Bcl-2/Bax ratio was increased in BDL-mice compared with sham controls. Anti-FasL monoclonal antibody injection in BDL-mice improved systolic and diastolic dysfunctions in cardiomyocytes, but had no effect in sham controls. A net pro-apoptotic balance exists in BDL hearts, mainly mediated by activation of the extrinsic pathway, and abrogation of apoptosis improved contractility. These results suggest that apoptosis contributes to depressed cardiac contractility in a murine model of cirrhotic cardiomyopathy.
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http://dx.doi.org/10.1042/CS20130642DOI Listing
October 2014

T2-weighted imaging of the heart--a pictorial review.

Eur J Radiol 2013 Oct 9;82(10):1755-62. Epub 2013 Jul 9.

Department of Diagnostic Imaging, Foothills Medical Centre, University of Calgary, Calgary, Canada.

Spin-Echo techniques in cardiovascular magnetic resonance (CMR) have been used for decades, primarily to image cardiac anatomy. More recently, T2-weighted (T2W) imaging has seen an increased role in CMR protocols, especially in tissue characterization in acute myocardial processes. This article will review current methodologies of cardiac T2W acquisition and their limitations, as well as approach to both semi-quantitative and quantitative analyses. The appearance and utility of T2W imaging in a myriad of pathologic myocardial processes such as acute myocardial infarction, acute viral myocarditis, reversible stress-related cardiomyopathy, hypertrophic cardiomyopathy, and cardiac sarcoidosis, will also be discussed.
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http://dx.doi.org/10.1016/j.ejrad.2013.06.005DOI Listing
October 2013

Unusual operation for tetralogy of Fallot.

Arch Cardiovasc Dis 2013 Mar 7;106(3):180-1. Epub 2012 Mar 7.

Adult Congenital Heart Clinic, Department of Cardiac Sciences, University of Calgary, Peter Lougheed Hospital, 3500 26, avenue Northeast, Calgary, AB T1Y 6J4, Canada.

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http://dx.doi.org/10.1016/j.acvd.2011.09.006DOI Listing
March 2013

Canadian Society for Cardiovascular Magnetic Resonance (CanSCMR) recommendations for cardiovascular magnetic resonance image analysis and reporting.

Can J Cardiol 2013 Mar 23;29(3):260-5. Epub 2012 Sep 23.

Montreal Heart Institute, Université de Montréal, Montreal, Québec, Canada.

Cardiovascular magnetic resonance (CMR) imaging is a rapidly developing technology that is becoming increasingly important in the diagnostic assessment of heart disease. Recognizing the need for recommendations to optimize the use of this technique, the Canadian Society for Cardiovascular Magnetic Resonance developed a task force to generate recommendations on the clinical use of parameters acquired by CMR imaging and how they should be reported. This article is the consensus report generated by the task force. The online material of this report provides such parameters for all relevant clinical settings, including pediatric and congenital applications. It considers the current clinical role of CMR, general requirements for CMR imaging, components of CMR studies, quantitative CMR image analysis, and appropriate contents of CMR reports. The recommendations are based on previously published recommendations on analysis and reporting and are the first of their kind. It is hoped that the use of these recommendations to guide daily clinical routine will help institutions offering CMR to adhere to high standards of quality according to the present state of the art.
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http://dx.doi.org/10.1016/j.cjca.2012.07.007DOI Listing
March 2013

Patterns of myocardial late enhancement: typical and atypical features.

Arch Cardiovasc Dis 2012 May 14;105(5):300-8. Epub 2012 Mar 14.

Stephenson Cardiovascular MR Centre, Libin Cardiovascular Institute of Alberta, University of Calgary, Canada.

Myocardial late enhancement, an imaging technique acquired after gadolinium administration, has become an integral part of cardiovascular magnetic resonance imaging over the past decade. Initially principally utilized for imaging myocardial infarction, more recently it has also become an invaluable tool for identifying myocardial scarring in other cardiomyopathic processes. Our experience using this technique has led us to identify several manifestations of late gadolinium enhancement imaging that can confound interpretation of pathology and potentially lead to misinterpretation and subsequently misdiagnosis for the patient. The purpose of this article is to review and illustrate typical and atypical myocardial late enhancement in the most common myocardial diseases seen in routine clinical practice.
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http://dx.doi.org/10.1016/j.acvd.2011.12.006DOI Listing
May 2012

Successful catheter-based occlusion of persistent left-sided superior vena cava draining into the left atrium.

Eur Heart J Cardiovasc Imaging 2012 Jan 3;13(1):122. Epub 2011 Nov 3.

Division of Cardiovascular Diseases, Adult Congenital Heart Disease Clinic, Peter Lougheed Hospital, University of Calgary, 3500 26 Avenue Northeast Calgary, AB, Canada.

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http://dx.doi.org/10.1093/ejechocard/jer225DOI Listing
January 2012

Imaging of congenital aorta-right atrial tunnel with electrocardiogram gated 64-multi-slice computed tomography.

Ann Thorac Surg 2011 Aug;92(2):743

Department of Radiology, Gil Hospital, Gachon University of Medicine and Science, Incheon, Republic of Korea.

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http://dx.doi.org/10.1016/j.athoracsur.2011.01.002DOI Listing
August 2011

Quantitative assessment of myocardial T2 relaxation times in cardiac amyloidosis.

J Magn Reson Imaging 2009 Nov;30(5):942-6

Division of Cardiothoracic Imaging, Department of Medical Imaging, University Health Network and Mount Sinai Hospital, Toronto, Canada.

Purpose: To evaluate cardiac MRI (CMR) in the diagnosis of cardiac amyloidosis by comparing the T2 relaxation times of left ventricular myocardium in a pilot patient group to a normal range established in healthy controls.

Materials And Methods: Forty-nine patients with suspected amyloidosis-related cardiomyopathy underwent comprehensive CMR examination, which included assessment of myocardial T2 relaxation times, ventricular function, resting myocardial perfusion, and late gadolinium enhancement (LGE) imaging. T2-weighted basal, mid, and apical left ventricular slices were acquired in each patient using a multislice T2 magnetization preparation spiral sequence. Slice averaged T2 relaxation times were subsequently calculated offline and compared to the previously established normal range.

Results: Twelve of the 49 patients were confirmed to have cardiac amyloidosis by biopsy. There was no difference in mean T2 relaxation times between the amyloid cases and normal controls (51.3 +/- 8.1 vs. 52.1 +/- 3.1 msec, P = 0.63). Eleven of the 12 amyloid patients had abnormal findings by CMR, eight having LGE involving either ventricles or atria and four demonstrating resting subendocardial perfusion defects.

Conclusion: CMR is a potentially valuable tool in the diagnosis of cardiac amyloidosis. However, calculation of myocardial T2 relaxation times does not appear useful in distinguishing areas of amyloid deposition from normal myocardium.
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http://dx.doi.org/10.1002/jmri.21918DOI Listing
November 2009

CT and MR imaging findings in patients with acquired heart disease at risk for sudden cardiac death.

Radiographics 2009 May-Jun;29(3):805-23

Division of Cardiothoracic Imaging, Department of Medical Imaging, University Health Network and Mount Sinai Hospital, 200 Elizabeth St, NCBS 1-562, Toronto, ON, Canada.

Noninvasive imaging is an important screening and diagnostic tool in conditions associated with sudden cardiac death. The most common cause of sudden cardiac death is coronary artery disease, with myocarditis, cardiac sarcoidosis, and dilated and infiltrative cardiomyopathies being less common acquired causes. Common risk factors for sudden cardiac death, regardless of the disease process, include severe ventricular dysfunction and the presence of macroscopic scar seen at delayed contrast material-enhanced imaging. Recent advances in electrocardiographically (ECG) gated cardiac magnetic resonance (MR) imaging and multidetector computed tomography (CT) have led to increased referrals for cross-sectional imaging; thus, cardiac radiologists should be familiar with the disease entities associated with sudden cardiac death. Inflammatory processes and cardiomyopathies are best depicted with cardiac MR imaging. Steady-state free precession cine sequences coupled with inversion-recovery prepared gradient-echo T1-weighted sequences performed after the intravenous administration of gadolinium-based contrast material should form the basis of cardiac MR imaging protocols for cardiomyopathy. A clinical history that is suggestive of myocardial ischemia, specific requests to exclude coronary artery disease, or contraindications for MR imaging may imply that multidetector CT would be more appropriate. Nevertheless, both cardiac MR imaging and ECG-gated multidetector CT offer robust diagnosis and risk stratification for individual disease processes associated with sudden cardiac death.
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http://dx.doi.org/10.1148/rg.293085715DOI Listing
August 2009

ALCAPA syndrome: not just a pediatric disease.

Radiographics 2009 Mar-Apr;29(2):553-65

Department of Diagnostic Imaging, Division of Cardiac Radiology, Ottawa Hospital, Ottawa, ON, Canada.

Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) syndrome is a rare congenital coronary artery anomaly. There are two types of ALCAPA syndrome: the infant type and the adult type, each of which has different manifestations and outcomes. Infants experience myocardial infarction and congestive heart failure, and approximately 90% die within the 1st year of life. Rarely, ALCAPA syndrome manifests in adults; it may be an important cause of sudden cardiac death. Historically, ALCAPA syndrome was diagnosed at conventional angiography. However, the development of electrogardiographically gated multidetector computed tomographic (CT) angiography and magnetic resonance (MR) imaging enables accurate noninvasive imaging. At MR imaging and multidetector CT angiography, findings include direct visualization of the left coronary artery arising from the main pulmonary artery. Reversed flow from the left coronary artery into the main pulmonary artery may be seen at steady-state free-precession cine and fast cine phase-contrast MR imaging. Because of its ability to assess myocardial viability, which can be used as a prognostic factor to direct the need for surgical repair, MR imaging plays an important role in patient treatment. Restoration of a dual-coronary-artery system is the ideal surgical treatment for ALCAPA syndrome.
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http://dx.doi.org/10.1148/rg.292085059DOI Listing
May 2009

Cardiac MRI and CT features of inheritable and congenital conditions associated with sudden cardiac death.

Eur Radiol 2009 Feb 16;19(2):259-70. Epub 2008 Sep 16.

Division of Cardiothoracic Imaging, Department of Medical Imaging, University Health Network and Mount Sinai Hospital, Toronto, Ontario, Canada.

Cardiac MRI (CMR) and electrocardiogram (ECG)-gated multi-detector computed tomography (MDCT) are increasingly important tools in the identification and assessment of cardiac-related disease processes, including those associated with sudden cardiac death (SCD). While the commonest cause of SCD is coronary artery disease (CAD), in patients under 35 years inheritable cardiomyopathies such as hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy are important aetiologies. CMR in particular offers both accurate delineation of the morphological abnormalities associated with these and other conditions and the possibility for risk stratification for development of ventricular arrhythmias with demonstration of macroscopic scar by delayed enhancement imaging with intravenous gadolinium.
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http://dx.doi.org/10.1007/s00330-008-1169-5DOI Listing
February 2009

Noninvasive quantitative measurement of myocardial and whole-body oxygen consumption using MRI: initial results.

Magn Reson Imaging 2009 Feb 6;27(2):147-54. Epub 2008 Aug 6.

Imaging Research, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, M4N 3M5, Canada.

The purpose of this study was to investigate the feasibility of a noninvasive approach that combines magnetic resonance imaging (MRI) oximetry and flow measurement to obtain the oxygen consumption in the myocardium and in the whole body. Thirteen healthy male volunteers [mean (+/-S.D.) age: 35+/-7 years] underwent this MR study, which included myocardial oxygen consumption (MVO(2)) measurements in 11 subjects and whole-body oxygen consumption (VO(2)) measurements in 8 subjects. In six subjects, both measurements were obtained. Five subjects had repeated MRI measurements of global MVO(2) in order to verify the reproducibility of this approach. The protocol included in vitro blood sample T(2)-%O(2) calibration, coronary sinus (CS) and main pulmonary artery (MPA) T(2) and phase contrast flow measurement and left ventricular (LV) mass calculation. Based on Fick's law, a global measurement of LV MVO(2) and whole-body VO(2) using MRI was feasible. The MVO(2) values were 11+/-3 ml/min per 100 g LV mass. For repeated measurements, differences in MVO(2) of 1 ml/min per 100 g LV mass appear detectable. The whole-body VO(2) values were 3.8+/-0.8 ml/min/kg body weight. MRI techniques that combine CS and MPA T(2), flow and LV mass measurements to quantify MVO(2) and whole-body VO(2) noninvasively in healthy subjects appear feasible, based on their correspondence to previously published work.
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http://dx.doi.org/10.1016/j.mri.2008.06.005DOI Listing
February 2009

Sub-aortic mitral impact lesion depicted by delayed enhancement cardiac magnetic resonance imaging.

Eur Heart J 2008 Oct 5;29(19):2449. Epub 2008 Apr 5.

Department of Medical Imaging, Toronto General Hospital, 200 Queen Street, Toronto, Canada M5G 2C4.

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http://dx.doi.org/10.1093/eurheartj/ehn157DOI Listing
October 2008

Diagnosis of paracardiac castleman disease by dynamic gadolinium-enhanced first pass perfusion magnetic resonance imaging.

Clin Med Case Rep 2008 1;1:127-31. Epub 2008 Oct 1.

Summary Castleman disease is an uncommon disorder affecting the lymphatic system and is characterised by atypical lymphocyte proliferation. The usual clinical presentation is of a solitary mass lesion, frequently within the thorax. A number of different imaging findings have been reported on CT and MRI. We present a case of paracardiac Castleman disease where the diagnosis was suggested by dramatic enhancement of the tumour mass during a dynamic MR perfusion sequence. To our knowledge this is the first report of the use of a first pass bolus tracking technique in the diagnosis of Castleman disease.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3785362PMC
http://dx.doi.org/10.4137/ccrep.s732DOI Listing
November 2013

MRI of hypertrophic cardiomyopathy: part 2, Differential diagnosis, risk stratification, and posttreatment MRI appearances.

AJR Am J Roentgenol 2007 Dec;189(6):1344-52

Department of Medical Imaging, The Prince Charles Hospital, Rode Rd., Chermside, Brisbane, Queensland 4032, Australia.

Objective: We present a two-part review about the use of MRI in patients with hypertrophic cardiomyopathy (HCM). This article, Part 2, covers the differential diagnosis, risk stratification, and posttreatment MRI follow-up appearances in these patients.

Conclusion: Cardiovascular MRI is a useful imaging tool for the diagnosis of HCM and follow-up of patients after either surgical myomectomy or septal ablation therapy. In addition, MRI can help to discriminate HCM from the differential diagnoses of other cardiomyopathies and cardiac disorders, and it can potentially identify the subset of patients at risk of sudden cardiac death.
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http://dx.doi.org/10.2214/AJR.07.2287DOI Listing
December 2007

MRI of hypertrophic cardiomyopathy: part I, MRI appearances.

AJR Am J Roentgenol 2007 Dec;189(6):1335-43

Department of Medical Imaging, The Prince Charles Hospital, Rode Rd., Chermside, Brisbane, Queensland 4032, Australia.

Objective: We present a two-part review about the use of MRI in patients with hypertrophic cardiomyopathy (HCM). This article, Part 1, focuses on the MRI appearances of HCM.

Conclusion: MRI has proven to be an important tool for the evaluation of patients suspected of having HCM because it can readily diagnose those with phenotypic expression of the disorder and can potentially identify the subset of patients at risk of sudden cardiac death.
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http://dx.doi.org/10.2214/AJR.07.2286DOI Listing
December 2007

Case 123: cardiac hemosiderosis.

Radiology 2007 Oct;245(1):292-5

Department of Medical Imaging, University Health Network, Toronto General Hospital, 200 Elizabeth St, Toronto, ON, Canada M5G 2N2.

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http://dx.doi.org/10.1148/radiol.2451040867DOI Listing
October 2007

The impact of pulmonary valve replacement after tetralogy of Fallot repair: a matched comparison.

Eur J Cardiothorac Surg 2007 Sep 12;32(3):462-8. Epub 2007 Jul 12.

The Division of Cardiology, Department of Pediatrics, University of Toronto, The Hospital for Sick Children, Toronto, Ontario, Canada.

Objective: While there are no controlled studies, pulmonary valve replacement (PVR) after late tetralogy of Fallot repair is performed for patients with symptoms, arrhythmia or ventricular dysfunction. We sought to determine the impact of PVR on clinical outcomes.

Methods: In a matched cohort study, 82 patients with PVR after tetralogy of Fallot repair without a history of ventricular arrhythmia were matched and compared with similarly followed non-PVR control subjects. A propensity-score adjusted analysis using repeated measures regression techniques was performed.

Results: For the PVR subjects, the mean age was 28 years with a mean duration follow-up of 9 years. Before PVR, these subjects were significantly more likely than matched non-PVR subjects to have had non-ventricular arrhythmias, symptoms, lower functional class, longer QRS duration, lower right ventricular ejection fraction and higher right ventricular pressure, and reduced exercise duration but not aerobic capacity. During follow-up, sudden death occurred in four non-PVR subjects compared with no PVR subjects, with three episodes of ventricular tachycardia in the PVR subjects versus none in the non-PVR subjects (p=0.49). Symptoms and functional class improved in the PVR subjects with no change in the non-PVR subjects (p<0.001). The change in QRS duration was not significantly different between PVR and non-PVR subjects (p=0.48). Oxygen consumption at peak exercise did not significantly change in either group. For PVR subjects, there was a significant qualitative reduction in pulmonary (p<0.001) and tricuspid valve regurgitation (p=0.009) and right ventricular size (p<0.001) and dysfunction (p<0.001) noted on echocardiography.

Conclusions: Symptoms and functional status are improved after late PVR, with a reduction in pulmonary and tricuspid valve regurgitation and right ventricular size and dysfunction. While a significant impact on arrhythmia was not detected, there were no sudden deaths in the PVR subjects.
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http://dx.doi.org/10.1016/j.ejcts.2007.06.009DOI Listing
September 2007

Magnetic resonance imaging of thoracic aortic pseudoaneurysm.

Can Assoc Radiol J 2006 Oct;57(4):238-45

Department of Diagnostic Imaging, University Hospitals' Network, Toronto, ON.

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October 2006
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