Yoo Ri Kim

Influence of Diabetes Mellitus on Long-Term (Five-Year) Outcomes of Drug-Eluting Stents and Coronary Artery Bypass Grafting for Multivessel Coronary Revascularization

Diabetes mellitus is a major risk factor for coronary artery disease (CAD) and for diffuse and progressive atherosclerosis. We evaluated the outcomes of drug-eluting stent (DES) placement and coronary artery bypass grafting (CABG) in 891 diabetic patients (489 for DES implantation and 402 for CABG) and 2,151 nondiabetic patients (1,058 for DES implantation and 1,093 for CABG) with multivessel CAD treated from January 2003 through December 2005 and followed up for a median 5.6 years. Outcomes of interest included death; the composite outcome of death, myocardial infarction (MI), or stroke; and repeat revascularization. In diabetic patients, after adjusting for baseline covariates, 5-year risk of death (hazard ratio 1.01, 95% confidence interval 0.77 to 1.33, p = 0.96) and the composite of death, MI, or stroke (hazard ratio 1.03, 95% confidence interval 0.80 to 1.31, p = 0.91) were similar in patients undergoing DES or CABG. However, rate of repeat revascularization was significantly higher in the DES group (hazard ratio 3.69, 95% confidence interval 2.64 to 5.17, p <0.001). These trends were consistent in nondiabetic patients (hazard ratio 0.80, 95% confidence interval 0.55 to 1.16, p = 0.23 for death; hazard ratio 0.77, 95% confidence interval 0.56 to 1.05, p = 0.10 for composite of death, MI, or stroke; hazard ratio 2.77, 95% CI 1.95 to 3.91, p <0.001 for repeat revascularization). There was no significant interaction between diabetic status and treatment strategy on clinical outcomes (p for interaction = 0.36 for death; 0.20 for the composite of death, MI, or stroke; and 0.40 for repeat revascularization). In conclusion, there was no significant prognostic influence of diabetes on long-term treatment with DES or CABG in patients with multivessel CAD.

Second coupling interval of nonsustained ventricular tachycardia to distinguish malignant from benign outflow tract ventricular tachycardias

BACKGROUND Idiopathic ventricular tachycardia (VT) originating from the outflow tract (OT) usually is considered a benign condition. In rare cases, patients with OT-VT suffer from syncope or even sudden cardiac death. OT-VT is frequently preceded by nonsustained VT (NSVT). OBJECTIVE The purpose of this study was to clarify if the ECG parameters of NSVTs could differentiate malignant from benign OT-VT. METHODS We retrospectively evaluated patients without structural heart disease who had documented OT-NSVT on ECG. ECG parameters were compared between patients with syncope, aborted sudden cardiac death, or ventricular fibrillation (malignant group, n = 36) and patients without syncope (benign group, n = 40). RESULTS There were no differences with regard to age and gender between the malignant and benign groups. On analysis of NSVT, the first coupling interval (CI) of NSVT was comparable between the 2 groups (458 ± 87 ms vs 485 ± 95 ms, P = .212). However, the second CI of NSVT beats was significantly shorter in the malignant group (313 ± 58 ms vs 385 ± 83 ms, P < .0001). During 48-month follow-up, the benign group had a significantly lower recurrence of clinical VT than the malignant group (P = .046). The malignant group frequently had more than 1 focus of VT, whereas the benign group showed only a single focus (1.82 vs 1.09, P = .023). CONCLUSION The second CI of NSVT in the malignant group was significantly shorter than that of the benign OT-VT group. Careful measurement of the second CI of NSVT may help identify the malignant form of OT-VT, enabling early treatment to prevent future cardiac events.

Electrocardiographic predictors of bradycardia-induced torsades de pointes in patients with acquired atrioventricular block

BACKGROUND Predictors of torsades de pointes (TdP) in bradyarrhythmia-induced acquired long QT syndrome are not well defined. OBJECTIVE The purpose of this study was to search for electrocardiographic (ECG) TdP predictors in patients with acquired atrioventricular block (AVB) and QT prolongation. METHODS We analyzed 12-lead ECGs from 20 patients (15 females, age 65.9 ± 15.6 years) with TdP episodes from among 898 AVB patients (2.2%) in 3 tertiary hospitals. The ECG repolarization parameters in TdP patients were compared with those of 80 age- and sex-matched control AVB patients with no TdP episodes. RESULTS TdP was initiated by premature ventricular complexes with a long-short sequence of activation. The average cycle length of the long sequence was 1289.9 ± 228.9 ms and was 2.3 ± 0.6 times longer than the cycle length of the short sequence. TdP patients had a significantly longer mean QT interval (716.4 ± 98.9 ms vs 523.2 ± 91.3 ms, P = .001), mean T peak to end interval (334.2 ± 59.1 ms vs 144.0 ± 73.7 ms, P = .001) and a higher T peak to end interval/QT ratio (0.49 ± 0.09 vs 0.27 ± 0.11, P = .001) compared with non-TdP controls. TdP patients showed a higher prevalence of notched T waves in which T2 was at least 3 mm taller than T1 (45.0% vs 1.3%, P = .001), triphasic T waves (30.0% vs 1.3%, P = .001), reversed asymmetry (20.0% vs 0%, P = .001), and T-wave alternans (35.0% vs 0%, P = .001). An algorithm combining these morphologic parameters was able to differentiate TdP patients from non-TdP patients with high sensitivity (85.0%) and specificity (97.5%). CONCLUSION An algorithm combining specific T-wave morphologies was useful for identifying patients with AVB who are at risk for developing TdP.

The Effect of Doubling the Statin Dose on Pro-Inflammatory Cytokine in Patients With Triple-Vessel Coronary Artery Disease

Background and Objectives Statin prevents atherosclerotic progression and helps to stabilize the plaque. According to a recent study, statin reduces inflammation in blood vessels. However, it has not been demonstrated to have any anti-inflammation reaction in patients who have been diagnosed as having a triple-vessel coronary artery disease (CAD). Subjects and Methods This study included a total of thirty (30) patients who had been diagnosed by coronary angiogram as having a triple-vessel CAD. Patients who already had been taking statin were given doubled dosage. An interview, physical examination and blood test were performed at the beginning of this study and three months later. Results After doubling the dose of statin, there was no statistically significant decrease in total cholesterol, low density lipoprotein-cholesterol, (increase in) high density lipoprotein-cholesterol and triglyceride in the blood test. C-reactive protein (CRP), an acute phase reactant, significantly decreased from 0.34 mg/dL at the beginning of the study to 0.12 mg/dL at the end of study (p<0.01). The interleukin-6 concentration also significantly decreased from 8.55 pg/dL to 4.81 pg/dL (p<0.001). No major cardiovascular events occurred and the dosage regimen was not modified during the close observation period. There was no difference in the symptoms of angina pectoris, established by World Health Organization Angina Questionnaires, before and after the dose increase. Liver enzymes remained within normal range with no significant increase before and after conducting this study. Conclusion Doubling the dose of statin alone significantly lowers pro-inflammatory cytokine concentration, which is closely related to the potential acute coronary syndrome, and CRP, a marker of vascular inflammation.

The exercise heart rate profile in master athletes compared to healthy controls

Endurance exercise protects the heart via effects on autonomic control of heart rate (HR); however, its effects on HR indices in healthy middle‐aged men are unclear. This study compared HR profiles, including resting HR, increase in HR during exercise and HR recovery after exercise, in middle‐aged athletes and controls. Fifty endurance‐trained athletes and 50 controls (all male; mean age, 48·7 ± 5·8 years) performed an incremental symptom‐limited exercise treadmill test. The electrocardiographic findings and HR profiles were evaluated. Maximal O2 uptake (52·6 ± 7·0 versus 34·8 ± 4·5 ml kg−1 min−1; P<0·001) and the metabolic equivalent of task (15·4 ± 1·6 versus 12·2 ± 1·5; P<0·001) were significantly higher in athletes than in controls. Resting HR was significantly lower in athletes than in controls (62·8 ± 6·7 versus 74·0 ± 10·4 beats per minute (bpm), respectively; P<0·001). Athletes showed a greater increase in HR during exercise than controls (110·1 ± 11·0 versus 88·1 ± 15·4 bpm; P<0·001); however, there was no significant between‐group difference in HR recovery at 1 min after cessation of exercise (22·9 ± 5·6 versus 21·3 ± 6·7 bpm; P = 0·20). Additionally, athletes showed a lower incidence of premature ventricular contractions (PVCs) during exercise (0·0% versus 24·0%; P<0·001). Healthy middle‐aged men participating in regular endurance exercise showed more favourable exercise HR profiles and a lower incidence of PVCs during exercise than sedentary men. These results reflect the beneficial effect of endurance training on autonomic control of the heart.

Long‐term luminal change after drug‐eluting stent implantation: Serial angiographic follow‐up study of the ZEST randomized trial

To evaluate long‐term patterns of luminal changes after implantation of different types of drug‐eluting stents (DES), we analyzed the serial angiographic outcomes of patients implanted with zotarolimus‐eluting stents (ZES), sirolimus‐eluting stents (SES), or paclitaxel‐eluting stents (PES).

Tachyarrhythmia Cycle Length in Appropriate versus Inappropriate Defibrillator Shocks in Brugada Syndrome, Early Repolarization Syndrome, or Idiopathic Ventricular Fibrillation

Background and Objectives Implantable cardioverter–defibrillators (ICDs) are indicated in patients with Brugada syndrome (BS), early repolarization syndrome (ERS), or idiopathic ventricular fibrillation (IVF) who are at high risk for sudden cardiac death. The optimal ICD programming for reducing inappropriate shocks in these patients remains to be determined. We investigated the difference in the mean cycle length of tachyarrhythmias that activated either appropriate or inappropriate ICD shocks in these three patient groups to determine the optimal ventricular fibrillation (VF) zone for minimizing inappropriate ICD shocks. Subjects and Methods We selected 41 patients (35 men) (mean age±standard deviation=42.6±13.0 year) who received ICD shocks between April 1996 and April 2014 to treat BS (n=24), ERS (n=9), or IVF (n=8). Clinical and ICD interrogation data were retrospectively collected and analyzed for all events with ICD shocks. Results Of the 244 episodes, 180 (73.8%) shocks were appropriate and 64 (26.2%) were inappropriate. The mean cycle lengths of the tachyarrhythmias that activated appropriate and inappropriate shocks were 178.9±28.7 ms and 284.8±24.4 ms, respectively (p<0.001). The cutoff value with the highest sensitivity and specificity for discriminating between appropriate and inappropriate shocks was 235 ms (sensitivity, 98.4%; specificity, 95.6%). When we programmed a single VF zone of ≤270 ms, inappropriate ICD shocks were reduced by 70.5% and appropriate shocks were missed in 1.7% of these patients. Conclusion Programming of a single VF zone of ≤270 ms in patients with BS, ERS, or IVF could reduce inappropriate ICD shocks, with a low risk of missing appropriate shocks.

Impact of Impaired Renal Function on the Incidence of Atrial Fibrillation following Radiofrequency Ablation of Cavotricuspid Isthmus-Dependent Atrial Flutter

Background and Objectives Atrial fibrillation (AF) occurs frequently after successful radiofrequency ablation (RFA) of cavotricuspid isthmus-dependent atrial flutter (CTI-AFL). Renal impairment has been implicated in the development of AF. The purpose of this study is to clarify the impact of impaired renal function on the incidence of AF after RFA of CTI-AFL. Subjects and Methods Between January 2001 and December 2013, 240 non-dialysis patients with no prior history of AF {mean age 55.9±15.2 years old; male, 192 (80.0%)} who had undergone successful CTI-AFL ablation were included in the present study. The baseline estimated glomerular filtration rate was calculated, and patients were divided into those with impaired renal function (<60 mL/min/1.73 m2) and those with preserved renal function (≥ 60 mL/min/1.73 m2). The incidence of AF was retrospectively analyzed. Results 69 (28.8%) patients experienced new onset AF during a median follow-up duration of 26 months (inter-quartile, 7-53). The incidence of AF was significantly higher in patients with impaired renal function than in those with preserved renal function {13/25 (52.0%) versus 56/215 (26.0%), log rank p=0.019}. Age, CHADS2 score, impaired renal function, and left atrial diameter were significantly associated with the incidence of AF in univariate Cox regression analysis. Multivariate analysis showed that age was the only significant predictor of AF incidence (hazard ratio, 1.024; 95% confidence interval, 1.004-1.044, p=0.020). Conclusion Patients with impaired renal function may require careful attention for the incidence of new onset AF following successful RFA of CTI-AFL.