Publications by authors named "Bum Sung Kim"

23 Publications

  • Page 1 of 1

Association between polyvascular disease and clinical outcomes in patients with cardiogenic shock: Results from the RESCUE registry.

Int J Cardiol 2021 Jul 8. Epub 2021 Jul 8.

Division of Cardiology, Heart Vascular Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.

Background: Clinical implications of systemic atherosclerosis in patients with cardiogenic shock (CS) remain unclear. This study investigated the association between polyvascular disease (PVD) and clinical outcome in CS patients.

Methods: A total of 1247 CS patients was enrolled from the RESCUE registry, a multicenter, observational cohort between January 2014 and December 2018. They were divided into two groups according to presence of PVD, defined as ≥2 coexistence of coronary artery disease, peripheral arterial disease, or cerebrovascular disease. Primary outcome was all-cause death during 12 months of follow-up.

Results: 136 (10.9%) patients were diagnosed with PVD. The risk of 12-month all-cause death was significantly higher in the PVD group than in the non-PVD group (54.4% versus 40.4%, adjusted hazard ratio [HR] 1.31, 95% confidence interval [CI] 1.02-1.69, p = 0.034). There was a significant interaction between PVD and vasoactive inotropic score (VIS) (p for interaction = 0.014). Among the 945 patients with VIS <84, PVD was associated with a higher risk of 12-month all-cause death (unadjusted HR 1.77, 95% CI 1.30-2.41, p = 0.030); among the 302 patients with VIS ≥84, the incidence of 12-month all-cause death was similar between the PVD and non-PVD groups (unadjusted HR 1.03, 95% CI 0.68-1.56, p = 0.301).

Conclusions: Presence of PVD was associated with 12-month all-cause mortality in patients with CS, especially for less severe forms of CS patients with VIS <84. Clinicaltrials.govnumber:NCT02985008.
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http://dx.doi.org/10.1016/j.ijcard.2021.07.008DOI Listing
July 2021

Clinical Characteristics and Predictors of In-Hospital Mortality in Patients With Cardiogenic Shock: Results From the RESCUE Registry.

Circ Heart Fail 2021 Jun 15;14(6):e008141. Epub 2021 Jun 15.

Division of Cardiology, Department of Medicine, Heart Vascular Stroke Institute, Samsung Medical Center (J.H.Y., K.H.C., T.K.P., J.M.L., Y.B.S., J.-Y.H., S.-H.C., H.-C.G.), Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.

Background: In the current era of mechanical circulatory support, limited data are available on prognosis of cardiogenic shock (CS) caused by various diseases. We investigated the characteristics and predictors of in-hospital mortality in Korean patients with CS.

Methods: The RESCUE study (Retrospective and Prospective Observational Study to Investigate Clinical Outcomes and Efficacy of Left Ventricular Assist Device for Korean Patients With CS) is a multicenter, retrospective, and prospective registry of patients that presented with CS. Between January 2014 and December 2018, 1247 patients with CS were enrolled from 12 major centers in Korea. The primary outcome was in-hospital mortality.

Results: In-hospital mortality rate was 33.6%. The main causes of shock were ischemic heart disease (80.7%), dilated cardiomyopathy (6.1%), myocarditis (3.2%), and nonischemic ventricular arrhythmia (2.5%). Vasopressors were used in 1081 patients (86.7%). The most frequently used vasopressor was dopamine (63.4%) followed by norepinephrine (57.3%). An intraaortic balloon pump was used in 314 patients (25.2%) and extracorporeal membrane oxygenator in 496 patients (39.8%). In multivariable analysis, age ≥70years (odds ratio [OR], 2.73 [95% CI, 1.89-3.94], <0.001), body mass index <25 kg/m (OR, 1.52 [95% CI, 1.08-2.16], =0.017), cardiac arrest at presentation (OR, 2.16 [95% CI, 1.44-3.23], <0.001), vasoactive-inotrope score >80 (OR, 3.55 [95% CI, 2.54-4.95], <0.001), requiring continuous renal replacement therapy (OR, 4.14 [95% CI, 2.88-5.95], <0.001), mechanical ventilator (OR, 3.17 [95% CI, 2.16-4.63], <0.001), intraaortic balloon pump (OR, 1.55 [95% CI, 1.07-2.24], =0.020), and extracorporeal membrane oxygenator (OR, 1.85 [95% CI, 1.25-2.76], =0.002) were independent predictors for in-hospital mortality.

Conclusions: The in-hospital mortality of patients with CS remains high despite the high utilization of mechanical circulatory support. Age, low body mass index, cardiac arrest at presentation, amount of vasopressor, and advanced organ failure requiring various support devices were poor prognostic factors for in-hospital mortality. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02985008.
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http://dx.doi.org/10.1161/CIRCHEARTFAILURE.120.008141DOI Listing
June 2021

Clinical Significance of Low-Flow Time in Patients Undergoing Extracorporeal Cardiopulmonary Resuscitation: Results from the RESCUE Registry.

J Clin Med 2020 Nov 7;9(11). Epub 2020 Nov 7.

Division of Cardiology, Heart Vascular Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea.

Limited data are available on the association between low-flow time and survival in patients with in-hospital cardiac arrest (IHCA) who undergo extracorporeal cardiopulmonary resuscitation (ECPR). We evaluated data from 183 IHCA patients who underwent ECPR as a rescue procedure. Patients were divided into two groups: patients undergoing extracorporeal membrane oxygenation as an adjunct to standard cardiopulmonary resuscitation for less than 38 min ( = 110) or for longer than 38 min ( = 73). The ECPR ≤ 38 min group had a significantly greater incidence of survival to discharge compared to the ECPR > 38 min group (40.0% versus 24.7%, = 0.032). The incidence of good neurologic outcomes at discharge tended to be greater in the ECPR ≤ 38 min group than in the ECPR > 38 min group (35.5% versus 24.7%, = 0.102). The incidences of limb ischemia ( = 0.354) and stroke ( = 0.805) were similar between the two groups, but major bleeding occurred less frequently in the ECPR ≤ 38 min group compared to the ECPR > 38 min group ( = 0.002). Low-flow time ≤ 38 min may reduce the risk of mortality and fatal neurologic damage and could be a measure of optimal management in patients with IHCA.
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http://dx.doi.org/10.3390/jcm9113588DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7695027PMC
November 2020

Usefulness of High-Sensitivity Troponin I to Predict Outcome in Patients With Newly Detected Atrial Fibrillation.

Am J Cardiol 2020 03 7;125(5):744-750. Epub 2019 Dec 7.

Division of Cardiology, Department of Medicine, Konkuk University Medical Center, School of Medicine, Konkuk University, Seoul 05030, Republic of Korea.

The prognostic role of high-sensitivity cardiac troponin I (hs-TnI) in patients with newly detected atrial fibrillation (AF) is not well established. We investigate the association of elevated hs-TnI with clinical outcomes and explore the utility of hs-TnI for risk assessment in patients with newly detected AF. From August 2014 to December 2016, 2,361 consecutive patients with newly detected AF were enrolled in a retrospective, single-center registry. Of these, 957 patients were selected and classified into 4 groups according to hs-TnI quartiles. The primary outcome was all-cause death during follow-up. The hs-TnI level was 3.6 ng/L or less in the lowest quartile (Q1), more than 3.6 ng/L to 10.1 ng/L or less in the second quartile (Q2), more than 10.1 ng/L to 22.0 ng/L or less in the third quartile (Q3), and more than 22.0 ng/L in the highest quartile (Q4). The median follow-up period was 19.3 months. In multivariable Cox regression model, Q4 has a higher risk of all-cause death (adjusted hazard ratio [HR]: 3.49; 95% confidence interval [CI]: 1.21 to 10.00; p = 0.02), readmission for heart failure (adjusted HR: 1.75; 95% CI: 1.01-3.05; p = 0.04), and readmission for revascularization (adjusted HR: 3.90; 95% CI: 1.25 to 12.17; p = 0.02) compared with Q1. Independent predictors of all-cause death were renal insufficiency (adjusted HR: 1.96; 95% CI: 1.08 to 3.53; p = 0.02), highest hs-TnI quartile (adjusted HR: 3.30; 95% CI: 1.18 to 9.27; p = 0.02) and anticoagulation therapy (adjusted HR: 0.51; 95% CI: 0.27 to 0.93; p = 0.03). Elevated hs-TnI is independently associated with higher mortality in patients with AF and serves as a valuable prognostic biomarker in patients with newly detected AF.
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http://dx.doi.org/10.1016/j.amjcard.2019.12.004DOI Listing
March 2020

Effect of Pre-Procedural Beta-Blocker on Clinical Outcome after Percutaneous Coronary Intervention in Acute Coronary Syndrome.

Int Heart J 2019 Nov 15;60(6):1284-1292. Epub 2019 Nov 15.

Division of Cardiology, Department of Internal Medicine, Konkuk University Medical Center, School of Medicine, Konkuk University.

The efficacy of pre-procedural beta-blocker use in patients with acute coronary syndrome (ACS) is not well established in the current percutaneous coronary intervention (PCI) era. We investigate the effect of pre-procedural beta-blocker use on clinical outcomes in patients with ACS undergoing PCI. Among 44,967 consecutive cases of PCI enrolled in the nationwide, retrospective, multicenter registry (K-PCI registry), 31,040 patients with ACS were selected and analyzed. We classified patients into pre-procedural beta-blocker group (n = 8,678) and pre-procedural no-beta-blocker group (n = 22,362) according to the use of beta-blockers at least for two weeks before index PCI. Propensity score-matching analysis was performed and resulted in 7,445 pairs. The primary outcome was in-hospital cardiac death. In propensity score-matched populations, the pre-procedural beta-blocker group had a lower incidence of in-hospital cardiac death compared with the pre-procedural no-beta-blocker group (1.1% versus 2.0%, unadjusted odds ratio [OR]: 0.56, 95% confidence interval [CI]: 0.42-0.73, P < 0.01). In subgroup analysis, the pre-procedural beta-blocker group had a lower incidence of in-hospital cardiac death, compared with the pre-procedural no-beta-blocker group in ST-segment elevation myocardial infarction subpopulation (3.1% versus 6.1%, unadjusted OR: 0.49, 95% CI: 0.34-0.71, P < 0.01) and non-ST-segment elevation myocardial infarction subpopulation (1.5% versus 2.9%, unadjusted OR: 0.51, 95% CI: 0.33-0.79, P < 0.01). However, in unstable angina subpopulation, the in-hospital cardiac death rate was comparable between both groups. In conclusion, the use of pre-procedural beta-blocker was associated with a lower risk of in-hospital cardiac death in patients with ACS undergoing PCI. This result adds to the body of evidence that use of pre-procedural beta-blocker in patients with ACS might be reasonable.
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http://dx.doi.org/10.1536/ihj.19-175DOI Listing
November 2019

The Impact of Metabolic Syndrome on the Incidence of Atrial Fibrillation: A Nationwide Longitudinal Cohort Study in South Korea.

J Clin Med 2019 Jul 24;8(8). Epub 2019 Jul 24.

Division of Cardiology, Department of Medicine, Heart Vascular Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea.

Aims: To evaluate the impact of metabolic syndrome (MetS) status on the incidence of atrial fibrillation (AF) in Koreans.

Methods And Results: Data obtained from the Korean National Health Insurance Service from 2009 to 2016 were analyzed. In total, 7,830,602 men and women (between 30 and 69 years of age) without baseline AF who underwent a national health examination between January 2009 and December 2009 were enrolled. Patients were evaluated to determine the impact of MetS status on their risk of developing AF until December 2016. Using the National Cholesterol Education Program Adult Treatment Panel III criteria, patients were placed into one of three groups depending on MetS component numbers: 0 (normal), 1-2 (Pre-MetS) or 3-5 (MetS). During a mean follow-up of 7.3 years, 20,708 subjects (0.26%) were diagnosed with AF. After multivariable adjustment, the risk of AF was significantly and positively correlated with MetS status (hazard ratios (HR) 1.391, 95% confidence interval (CI) 1.322-1.464 in Pre-MetS and HR 1.722, 95% CI 1.621-1.829 in MetS). When subgroup analyses were conducted according to MetS components, abdominal obesity (HR 1.316, p < 0.001), elevated blood pressure (HR 1.451, p < 0.001), and elevated fasting glucose (HR 1.163, p < 0.001) were associated with an increased risk of AF.

Conclusion: MetS and pre-MetS are significantly associated with an increased risk of AF in Korean adults. Of the MetS components, abdominal obesity, elevated blood pressure, and elevated fasting glucose are potent risk factors for the risk of AF in this population.
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http://dx.doi.org/10.3390/jcm8081095DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6723247PMC
July 2019

Benefit of Prolonged Dual Antiplatelet Therapy After Implantation of Drug-Eluting Stent for Coronary Bifurcation Lesions: Results From the Coronary Bifurcation Stenting Registry II.

Circ Cardiovasc Interv 2018 07;11(7):e005849

Division of Cardiology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea (Y.B.S., S.-H.C., S.W.C., B.S.K., H.-C.G., J.-Y.H.).

Background: Whether prolonged dual antiplatelet therapy (DAPT) improves clinical outcomes after percutaneous coronary intervention for coronary bifurcation lesion is uncertain.

Methods And Results: We evaluated 2082 patients who were treated with drug-eluting stent for bifurcation lesions and were event free (no death, myocardial infarction [MI], cerebrovascular accident, stent thrombosis, or any revascularization) at 12 months after the index procedure. Patients were divided into 2 groups: DAPT ≥12-month group (n=1776) and DAPT <12-month group (n=306). Primary outcome was all-cause death or MI. At 4 years after the index procedure, death or MI occurred less frequently in the DAPT ≥12-month group than the DAPT <12-month group (2.8% versus 12.3%; adjusted hazard ratio, 0.21; 95% confidence interval, 0.13-0.35; <0.001). After propensity score matching, incidence of death or MI was still lower in the DAPT ≥12-month group than the DAPT <12-month group (2.6% versus 12.3%; adjusted hazard ratio, 0.22; 95% confidence interval, 0.12-0.38; <0.001). In subgroup analysis, the treatment effect of prolonged DAPT was consistent across subgroups regardless of lesion location, stenting technique, or type of used drug-eluting stent.

Conclusions: The risk of all-cause death or MI was significantly lower in the ≥12-month DAPT group than the <12-month DAPT group after percutaneous coronary intervention for bifurcation lesion using drug-eluting stent. Our results suggest that prolonged DAPT may improve long-term clinical outcomes after percutaneous coronary intervention for bifurcation lesions.

Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01642992.
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http://dx.doi.org/10.1161/CIRCINTERVENTIONS.117.005849DOI Listing
July 2018

Association between preoperative high sensitive troponin I levels and cardiovascular events after hip fracture surgery in the elderly.

J Geriatr Cardiol 2018 Mar;15(3):215-221

Division of Cardiology, Department of Medicine, Konkuk University Medical Center, 120-1 Neungdong-ro, Hwayang-dong, Gwangjin-gu, Seoul, Republic of Korea.

Objective: Cardiovascular complications contribute to postoperative morbidity and mortality in elderly hip fracture patients. Limited data are available regarding which preoperative risk factors predict cardiovascular course following hip fracture surgery (HFS). We used high sensitive troponin I (hs-TnI) assays and clinical parameters to identify preoperative risk factors associated with major adverse cardiac events (MACE) in elderly hip fracture patients.

Method: From August 2014 to November 2016, 575 patients with hip fracture were enrolled in a retrospective, single-center registry. A total of 262 of these patients underwent HFS and hs-TnI assays. MACE was defined as postoperative all-cause deaths, heart failure (HF), new-onset atrial fibrillation (AF), myocardial infarction (MI) and cardiovascular re-hospitalization that occurred within 90 days postoperative.

Results: Of 262 HFS patients, MACE developed following HFS in 65 (24.8%). Patients with MACE were older and had higher rates of renal insufficiency, coronary artery disease, prior HF, low left ventricular ejection fraction and use of beta blockers; higher levels of hs-TnI and N-terminal pro-brain natriuretic peptide (NT-proBNP) and higher revised cardiac risk index. A preoperative hs-TnI ≥ 6.5 ng/L was associated with high risk of postoperative HF, new-onset AF and MACE. In multivariable analysis, preoperative independent predictors for MACE were age > 80 years [adjusted hazard ratio (HR): 1.79, 95% confident interval (CI): 1.03-3.13, = 0.04], left ventricular ejection fraction (LVEF) < 50% (adjusted HR: 3.17, 95% CI: 1.47-6.82, < 0.01) and hs-TnI > 6.5 ng/L (adjusted HR: 3.75, 95% CI: 2.09-6.17, < 0.01).

Conclusion: In elderly patients with hip fracture who undergo HFS, a preoperative assessment of hs-TnI may help the risk refinement of cardiovascular complications.
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http://dx.doi.org/10.11909/j.issn.1671-5411.2018.03.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5919809PMC
March 2018

Long-term Survival Benefit of Statin in Patients with Coronary Chronic Total Occlusion without Revascularization.

J Korean Med Sci 2018 Apr 13;33(18):e134. Epub 2018 Apr 13.

Division of Cardiology, Department of Internal Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.

Background: Limited data are available on the efficacy of statin therapy in stable ischemic heart disease with chronic total occlusion (CTO) without revascularization. We investigated whether statin therapy could be beneficial in stable patients with CTO without revascularization.

Methods: From March 2003 to February 2012, 2,024 patients with at least one CTO were enrolled in a retrospective, single-center registry; 664 of these patients were managed conservatively without an initial revascularization strategy. Among them, we excluded CTO cases involving acute coronary syndrome, in-hospital death or incomplete data and classified 551 patients into statin (n = 369) and non-statin (n = 182) groups according to use of statin at discharge. Propensity score matching analysis was also performed in 148 pairs. The primary outcome was cardiac death.

Results: The median overall follow-up duration was 45.7 months (interquartile range: 19.9-70.5 months). Cardiac death occurred in 22 patients (6.0%) in the statin group vs. 24 patients (13.2%) in the non-statin group ( < 0.001). In propensity score matching analysis, statin therapy was associated with a low risk of cardiac death (adjusted hazard ratio [HR], 0.39; 95% confidence interval [CI], 0.18-0.85; = 0.022) and major adverse cardiac events (adjusted HR, 0.66; 95% CI, 0.43-0.98; = 0.043). On multivariate analysis, independent predictors for cardiac death were age > 70 years, renal insufficiency, prior myocardial infarction, left ventricular ejection fraction < 40%, proximal-to-mid CTO location, and no use of statin in CTO patients.

Conclusion: Statin therapy at discharge may be associated with a reduction in long-term cardiac mortality in stable CTO patients without revascularization.
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http://dx.doi.org/10.3346/jkms.2018.33.e134DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5920123PMC
April 2018

Diagnostic value of the corrected QT difference between leads V1 and V6 in patients with acute pulmonary thromboembolism.

Medicine (Baltimore) 2017 Oct;96(43):e8430

The Department of Internal Medicine, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Korea.

In acute pulmonary thromboembolism (PTE), right ventricular pressure overload impairs right-sided cardiac conduction and repolarization. We hypothesized that if heterogeneity of repolarization between right and left ventricles occurs in acute PTE, there would be the difference of repolarization between them. Therefore, we aimed to evaluate the diagnostic value of corrected QT interval (QTc) difference between leads V1 and V6 (V1 - V6) in patients with acute PTE.A total of 89 patients with suspected acute PTE who underwent computed tomographic angiography (CTA) were enrolled from January to December 2015. PTE was identified by CTA. We compared electrocardiographic (ECG) parameters, especially QTc difference (V1 - V6) between patients with PTE and those without PTE.Acute PTE was finally diagnosed in 45 patients. Clinical situations including the chief complaint were not different between PTE and non-PTE groups. S1Q3T3, a traditional ECG marker, had no diagnostic value for acute PTE. Patients with PTE had a significantly longer mean QTc in V1 (454.6 ± 44.3 vs 417.5 ± 31.3 ms, P < .001) and larger QTc difference (V1 - V6) (34.8 ± 30.5 vs -12.5 ± 16.6 ms, P < .001) than non-PTE controls. QTc difference (V1 - V6) was negative in all patients without PTE. PTE patients had a higher prevalence of T wave inversion in leads III (51.1% vs 29.5%, P = .038) and V1 (82.2% vs 38.6%, P < .001). A QTc difference (V1 - V6) of ≥20 ms identified PTE with 82.2% sensitivity, 100.0% specificity, and 100.0% positive predictive value.QTc difference (V1 - V6) had an excellent diagnostic value for differentiating patients with and without acute PTE.
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http://dx.doi.org/10.1097/MD.0000000000008430DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5671877PMC
October 2017

Predictors and long-term clinical outcomes of newly developed atrial fibrillation in patients with cardiac implantable electronic devices.

Medicine (Baltimore) 2016 Jul;95(28):e4181

Division of Cardiology, Department of Medicine, Konkuk University Medical Center, Hwayang-dong Division of Cardiology, Department of Medicine, Heart Vascular and Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Gangnam-gu, Seoul, Republic of Korea.

Objective: To evaluate predictors and long-term prognosis of atrial fibrillation (AF) following cardiac implantable electronic device (CIED) implantation in patients without history of AF.

Methods: From May 1994 to April 2014, 1825 patients with CIED were enrolled in a retrospective, single-center registry. A total of 880 patients from the registry without prior documented AF history were included in the final analysis and were placed into either non-detected AF (NDAF) group or CIED-detected AF group according to development of AF over a follow-up period of 7 years. AF development was defined as any paroxysmal atrial tachyarrhythmia (atrial rate ≥ 180 beats/min) lasting at least 5 minutes according to CIED records.

Results: Overall, 122 (13.8%) of the 880 patients experienced new development of AF during follow-up period. According to multivariate analysis, the independent predictors for development of AF were prior heart failure (hazard ratio [HR], 2.40; 95% confidence interval [CI], 1.50-3.85; P < 0.001), prior sinus node dysfunction (HR, 2.33; 95% CI, 1.62-3.55; P < 0.001), and left atrium volume index of 38.5 mL/m or more (HR, 2.01; 95% CI, 1.23-3.30; P = 0.005). In CDAF group, the risk of heart failure readmission (adjusted HR, 3.79; 95% CI, 1.99-7.22; P < 0.001) and stroke readmission (adjusted HR, 5.33; 95% CI, 1.58-17.97; P = 0.007) was higher than in nondetected AF group.

Conclusion: In patients with CIED, prior history of heart failure, sinus node dysfunction, and LA volume index ≥38.5 mL/m were independent predictors of new AF cases. Newly developed AF was significantly associated with increased risk of HF and stroke readmission, according to long-term follow up.
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http://dx.doi.org/10.1097/MD.0000000000004181DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4956807PMC
July 2016

Optimal Medical Therapy vs. Percutaneous Coronary Intervention for Patients With Coronary Chronic Total Occlusion - A Propensity-Matched Analysis.

Circ J 2016 19;80(1):211-7. Epub 2015 Nov 19.

Division of Cardiology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine.

Background: Limited data are available on the long-term clinical outcomes of coronary chronic total occlusion (CTO) patients who receive optimal medical therapy (OMT) compared with percutaneous coronary intervention (PCI).

Methods And Results: Between March 2003 and February 2012, 2,024 patients with CTO were enrolled in a single-center registry. Among this patient group, we excluded CTO patients who underwent coronary artery bypass grafting and classified patients into the OMT group (n=664) or PCI group (n=883) according to initial treatment strategy. Propensity-score matching was also performed. The primary outcome was cardiac death. The median follow-up duration was 45.8 (interquartile range: 22.8-71.1) months. In the PCI group, 699 patients (79.2%) underwent successful revascularization. In the propensity-score matched population (533 pairs), there was no significant difference in the rate of cardiac death between the OMT and PCI groups (hazard ratio, 1.57; 95% confidence interval, 0.91-2.72, P=0.11). In the subgroup analysis, there were no significant interactions between the PCI strategy and cardiac death among several subgroups except that regarding collateral flow grades 0-2 vs. those with grade 3 (P=0.01).

Conclusions: As an initial treatment strategy, PCI did not reduce cardiac death compared with OMT for the treatment of CTO in the drug-eluting stent era.
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http://dx.doi.org/10.1253/circj.CJ-15-0673DOI Listing
October 2016

Association of periprocedural myocardial infarction with long-term survival in patients treated with coronary revascularization therapy of chronic total occlusion.

Catheter Cardiovasc Interv 2016 May 3;87(6):1042-9. Epub 2015 Nov 3.

Heart Vascular and Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.

Objective: To evaluate the impact of periprocedural myocardial infarction (PMI) on long-term survival after coronary revascularization in patients with chronic total occlusion (CTO).

Background: Little is known about the clinical impact of PMI on long-term cardiac mortality after CTO revascularization in patients with stable angina.

Methods: We analyzed data from 927 patients with CTO and stable angina who were treated with coronary artery bypass grafting (CABG, n = 367) or percutaneous coronary intervention (PCI, n = 560). PMI was defined as a peak CK-MB ≥ 3 times the upper limit of normal (ULN) after PCI or a CK-MB ≥ 5 times the ULN after CABG. The primary outcome was cardiac death in patients with PMI (PMI group, n = 118 [12.7%]) or without PMI (no-PMI group, n = 809 [87.3%]) after revascularization.

Results: During a median follow-up of 42 months, PMI occurred in 118 patients (12.7% of the overall study population). Fifty-nine patients treated with PCI (10.5% of PCI subgroup) and 59 patients treated with CABG (16.1% of CABG subgroup) suffered from PMI. In multivariate analysis, the PMI group and the no-PMI group had a similar incidence of cardiac death (hazard ratio [HR] 0.57; 95% confidence interval [CI] 0.20 to 1.62; P = 0.29).

Conclusions: PMI may not be associated with increased cardiac mortality after coronary revascularization in patients with stable CTO. © 2015 Wiley Periodicals, Inc.
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http://dx.doi.org/10.1002/ccd.26286DOI Listing
May 2016

Electrochemical Performances of Li2MnSiO4 Cathodes Synthesized by Mechanical Alloying Process.

J Nanosci Nanotechnol 2015 Mar;15(3):2418-21

We report the fabrication and electrochemical properties of Li2MnSiO4 powders produced by various solid-state reactions, such as ball-, attrition-, and bead-milling. Li2MnSiO4 powders prepared by bead-milling had the smallest particle sizes (~100 nm) and the largest amount of surface carbon (~20 wt%), which were produced by adding sucrose during milling process. The surface carbon layer can improve electronic/ionic conductivity of Li2MnSiO4 as cathode material for lithium ion battery. As expected, the bead-milled Li2MnSiO4 powder electrode showed the best electrochemical performance of the electrode materials obtained by the various solid-state reactions. This is attributed to the small particle size and facile electronic transport through the conductive carbon layer on each Li2MnSiO4 particle.
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http://dx.doi.org/10.1166/jnn.2015.10251DOI Listing
March 2015

Clinical outcomes of multiple chronic total occlusions in coronary arteries according to three therapeutic strategies: Bypass surgery, percutaneous intervention and medication.

Int J Cardiol 2015 Oct 15;197:2-7. Epub 2015 Jun 15.

Division of Cardiology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University, School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 135-710, Republic of Korea. Electronic address:

Background: Limited data exist regarding clinical outcomes of multiple chronic total occlusions (CTOs) according to therapeutic strategies, coronary artery bypass grafting (CABG), percutaneous coronary intervention (PCI), and medical treatment (MT).

Methods: From March 2003 to February 2012, a total of 2024 patients with at least one CTO were enrolled in retrospective, single-center registry. 393 patients with at least two CTOs were categorized based on the intention-to-treat principle. Propensity-score matching was performed. The primary outcome was major adverse cardiac and cerebral events (MACCE).

Results: Of 393 patients with multiple CTOs, 169 patients (43%) were referred for CABG, 130 (33%) for PCI, and 94 (24%) for MT. Median overall follow-up duration was 46.5 (interquartile range 22.7 to 74.6) months. After propensity-score matching analysis, CABG had lower rates of MACCE when compared with PCI (HR=0.43, 0.21-0.85, P=0.01) and MT (HR=0.10, 0.04-0.27, P<0.01). Rates of repeat revascularization was significantly lower in CABG, compared with PCI (HR=0.05, 0.01-0.40, P<0.01) and MT (HR=0.01, 0.00-0.54, P=0.02). CABG had similar rates of cardiac death compared with PCI group (HR=0.97, 0.37-2.53, P=0.95), but had significantly lower rates of cardiac death compared with MT (HR=0.24, 0.08-0.75, P=0.01).

Conclusions: For management of multiple CTOs, MT alone was associated with higher incidence of cardiac death and MACCE compared with CABG. PCI was associated with higher incidence of MACCE, as driven by higher repeat revascularization rate. These findings suggest that CABG might be associated with better clinical outcome and considered as the preferred treatment strategy in patients with multiple CTOs.
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http://dx.doi.org/10.1016/j.ijcard.2015.06.017DOI Listing
October 2015

Enhanced low-temperature power density of solid oxide fuel cell by nickel nanoparticle infiltration into pre-fired Ni/yttria-stabilized zirconia anode.

J Nanosci Nanotechnol 2014 Dec;14(12):8974-7

The Ni/yttria-stabilized zirconia (YSZ) anode morphology of an anode-supported solid oxide fuel cell (SOFC) unit cell was improved by nickel nanoparticle infiltration. A colloidal route was selected for efficient fabrication of nickel metal nanoparticles and subsequent infiltration into the Ni/YSZ anode of a pre-fired SOFC unit cell. The power density of the anode-supported SOFC unit cell was measured by the potentiostatic method to investigate the effect of nickel nanoparticle infiltration. The increase in the power density of the Ni/YSZ anode with nickel nanoparticle infiltration became gradually less significant as the SOFC operating temperature increased from 700 to 800 degrees C. The improved performance of the Ni/YSZ anode with nickel nanoparticle infiltration compared to that of an anode without nickel nanoparticles is tentatively attributed to two factors: The discretely distributed nanoparticles on the nanostructured electrodes exhibited significant catalytic effects on the electrochemical performance of the electrodes, in addition to substantially increasing the triple phase boundary lengths.
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http://dx.doi.org/10.1166/jnn.2014.10072DOI Listing
December 2014

Surface oxidation behaviors of Cd-rich CdSe quantum dot phosphors at high temperature.

J Nanosci Nanotechnol 2014 Oct;14(10):8024-7

The optical properties of quantum dots (QDs) are altered by exposure to air and light; upon such exposure, the quantum yield is typically reduced. Improved understanding of surface oxidation and oxide-layer behavior, both of which influence the photoluminescence of QDs, is necessary for advancing the use of QDs. In this study, the oxide layer properties of QDs are investigated. The QDs are synthesized and subsequently oxidized by heat treatment in atmospheric conditions, and the luminescence properties of the resultant QDs are investigated. The emission properties of QDs are characterized by photoluminescence. The composition and bonding structure of oxidized CdSe QDs are investigated by X-ray photoelectron spectroscopy (XPS). The XRD peaks of oxidized CdSe QDs match CdSe and CdO peaks. CdO is formed by partial oxidation of CdSe QDs. Transmission electron microscopy (TEM) image is confirmed morphology of oxidation before and after of CdSe QDs.
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http://dx.doi.org/10.1166/jnn.2014.9389DOI Listing
October 2014

Improvement of dispersion stability and optical properties of CdSe/ZnSe structured quantum dots by polymer coating.

J Nanosci Nanotechnol 2014 Oct;14(10):7636-40

In this study, CdSe core and CdSe/ZnSe core/shell quantum dots with a narrow size distribution were synthesized in a micro-reactor. A PMMA coating applied to the surface of CdSe/ZnSe core/shell QDs to prevent degradation gave improved dispersion stability compared to the CdSe core and CdSe/ZnSe core/shell. Many previous approaches to dispersion stability have not been quantitatively assessed. The dispersion stability was confirmed by multiple light scattering measurement. Additionally, the PMMA-coated CdSe/ZnSe QDs showed greatly improved optical properties with a photoluminescence quantum yield up to 80%. This structural motif is expected to prevent the degradation of QDs.
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http://dx.doi.org/10.1166/jnn.2014.9385DOI Listing
October 2014

Time to peak velocity of aortic flow is useful in predicting severe aortic stenosis.

Int J Cardiol 2014 Apr 22;172(3):e443-6. Epub 2014 Jan 22.

Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea. Electronic address:

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http://dx.doi.org/10.1016/j.ijcard.2013.12.318DOI Listing
April 2014

Enhancement of thermal conductive pathway of boron nitride coated polymethylsilsesquioxane composite.

J Nanosci Nanotechnol 2013 Nov;13(11):7695-700

Department of Bionano Technology/Fusion Chemical Enginnering, Hanyang University, Ansan 426-791, Korea.

We report here in the fabrication of enhanced thermal conductive pathway nanocomposites of boron nitride (BN)-coated polymethylsilsesquioxane (PMSQ) composite beads using isopropyl alcohol (IPA) as a mixing medium. Exfoliated and size-reduced boron nitride particles were successfully coated on the PMSQ beads and explained by surface charge differences. A homogeneous dispersion and coating of BN on the PMSQ beads using IPA medium was confirmed by SEM. Each condition of the composite powder was carried into the stainless still mould and then hot pressed in an electrically heated hot press machine. Three-dimensional percolation networks and conductive pathways created by exfoliated BN were precisely formed in the nanocomposites. The thermal conductivity of nanocomposites was measured by multiplying specific gravity, specific heat, and thermal diffusivity, based upon the laser flash method. Densification of the composite resulted in better thermal properties. For an epoxy reinforced composite with 30 vol% BN and PMSQ, a thermal conductivity of nine times higher than that of pristine PMSQ was observed.
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http://dx.doi.org/10.1166/jnn.2013.7826DOI Listing
November 2013

Highly efficient reduction of graphene oxide using ammonia borane.

Chem Commun (Camb) 2013 Jul;49(59):6665-7

School of Chemical Engineering and Bioengineering, University of Ulsan, Namgu, Daehakro 93, Ulsan 680-749, Republic of Korea.

We introduce ammonia borane, a versatile reducing agent for graphene oxide (GO) reduction in both aqueous and organic solvents; it is nontoxic and more effective than hydrazine. More interestingly, ammonia borane reduction of GO tetrahydrofuran produced higher nitrogen- and boron-doped graphene that exhibited high supercapacitor performance.
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http://dx.doi.org/10.1039/c3cc43503bDOI Listing
July 2013

Slow Coronary Flow is Related to Increased Carotid Intima-Media Thickness but Not Pulse Wave Velocity.

Korean Circ J 2011 Nov 29;41(11):666-70. Epub 2011 Nov 29.

Department of Cardiovascular Medicine, Konkuk University School of Medicine, Seoul, Korea.

Background And Objectives: Slow coronary flow (SCF) is characterized by delayed contrast dye opacification without significant stenosis of epicardial coronary arteries. However, the pathophysiology and clinical implications of SCF are not fully understood. Some reports have suggested that SCF might be caused by atherosclerosis in the coronary artery microvasculature. Measuring carotid intima-media thickness (IMT) and pulse wave velocity (PWV), which are non-invasive and simple diagnostic tools, was developed to detect subclinical atherosclerosis. Thus, we determined IMT and PWV, and their possible relationship in a SCF group and a normal coronary flow (NCF) group of patients.

Subjects And Methods: We included 101 patients who complained of chest pain but had a normal coronary angiogram. Thrombolysis in Myocardial Infarction frame count (TIMI frame count, TFC) was evaluated in the left and right coronary arteries. We defined SCF as a TFC of more than 25. Carotid IMT was measured by ultrasonography in both common carotid arteries. PWV was calculated from pulse transit time between the brachial and ankle arteries.

Results: Fifteen patients were included in the SCF group and 86 patients in the NCF group. Male patients (n=11, 73.3%) were significantly more common in the SCF group than in the NCF group (n=37, 43.0%, p<0.05). The TFC of the SCF and NCF groups were 28.8±3.5 and 15.7±4.5, respectively. The carotid IMT in the SCF group increased significantly compared to that in the NCF group (1.2±0.3 mm vs. 0.8±0.1 mm, p<0.01). However, no significant difference in PWV was observed between the two groups.

Conclusion: SCF may reflect early atherosclerotic changes in the coronary artery microvasculature.
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http://dx.doi.org/10.4070/kcj.2011.41.11.666DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3242022PMC
November 2011

[Cytomegalovirus infection-related spontaneous intestinal perforation and aorto-enteric fistula after abdominal aortic aneurysmal repair].

Korean J Gastroenterol 2010 Jan;55(1):62-7

Department of Internal Medicine, Konkuk University School of Medicine, Seoul, Korea.

Gastrointestinal complications (GI) after thoracoabdominal aortic repair can be classified as biliary disease, heptic dysfunction, pancreatitis, GI bleeding, peptic ulcer disease, bowel ischemia, paralytic ileus, and aortoenteric fistula. Theses complications are associated with high post operative morbidity and mortality. Most of the aortoenteric fistulae after thoracoabdominal aortic surgery are found at the duodenum, near the surgical site. These rare complications are caused by an indirect communication with abdominal aorta that originated from an aneursymal formation ruptured into the duodenum. Such aorto-duodenal fistula formation is considered as a result of inflammatory change from secondary infection near the surgical instruments. Herein, we report two cases of massive upper GI bleeding from aorto-duodenal fistulae and spontaneous lower GI perforation related to cytomegalovirus infection after abdominal aortic aneurysmal repair operations.
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http://dx.doi.org/10.4166/kjg.2010.55.1.62DOI Listing
January 2010
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