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Background Studies on the efficacy of implantable cardioverter-defibrillator (ICD) therapy for primary prevention in Asian patients are relatively lacking compared to those for secondary prevention. Also, it is important to stratify which patients will benefit from ICD therapy for primary prevention. Methods Of 483 consecutive patients who received new implantation of ICD in 9 centers in Korea, 305 patients with reduced left ventricular systolic function and/or documented ventricular fibrillation/tachycardia were enrolled and divided into primary (n = 167) and secondary prevention groups (n = 138). Results During mean follow-up duration of 2.6 ± 1.6 years, appropriate ICD therapy occurred in 78 patients (25.6%), and appropriate ICD shock and anti-tachycardia pacing occurred in 15.1% and 15.1% of patients, respectively. Appropriate ICD shock rate was not different between the two groups (primary 12% vs. secondary 18.8%, P = 0.118). However, appropriate ICD therapy rate including shock and anti-tachycardia pacing was significantly higher (primary 18% vs. secondary 34.8%, P = 0.001) in the secondary prevention group. Type of prevention and etiology, appropriate and inappropriate ICD shock did not affect all-cause death. High levels of N-terminal pro-B-type natriuretic peptide, New York Heart Association functional class, low levels of estimated glomerular filtration ratio, and body mass index were associated with death before appropriate ICD shock in the primary prevention group. When patients were categorized in 5 risk score groups according to the sum of values defined by each cut-off level, significant differences in death rate before appropriate ICD shock were observed among risk 0 (0%), 1 (3.6%), 2 (3%), 3 (26.5%), and 4 (40%) (P < 0.001). Conclusion In this multicenter regional registry, the frequency of appropriate ICD therapy is not low in the primary prevention group. In addition, combination of poor prognostic factors of heart failure is useful in risk stratification of patients who are not benefiting from ICD therapy for primary prevention., Graphical Abstract

BACKGROUND AND OBJECTIVES This study was performed to describe clinical characteristics of patients with left ventriculars (LV) dysfunction and implantable cardioverter-defibrillator (ICD), and to evaluate the effect of ICD therapy on survival in Yeongnam province of Korea. SUBJECTS AND METHODS From a community-based device registry (9 centers, Yeongnam province, from November 1999 to September 2012), 146 patients with LV dysfunction and an ICD implanted for primary or secondary prophylaxis, were analyzed. The patients were divided into two groups, based on the etiology (73 with ischemic cardiomyopathy and 73 with non-ischemic cardiomyopathy), and indication for the device implantation (36 for primary prevention and 110 for secondary prevention). The cumulative first shock rate, all cause death, and type and mode of death, were determined according to the etiology and indication. RESULTS Over a mean follow-up of 3.5 years, the overall ICD shock rate was about 39.0%. ICD shock therapy was significantly more frequent in the secondary prevention group (46.4% vs. 16.7%, p=0.002). The cumulative probability of a first appropriate shock was higher in the secondary prevention group (p=0.015). There was no significant difference in the all-cause death, cardiac death, and mode of death between the groups according to the etiology and indication. CONCLUSION Studies from this multicenter regional registry data shows that in both ischemic and non-ischemic cardiomyopathy patients, the ICD shock therapy rate was higher in the secondary prevention group than primary prevention group.

Background and Objectives: Coronary lesions with mismatched functional and anatomical significance are not uncommon. We as sessed the accuracy and predictors of mismatch between fractional flow reserve (FFR) and quantitative coronary angiography (QCA) analy ses in patients with coronary lesions. Subjects and Methods: A total of 643 lesions with pre-interventional FFR and QCA measurements were consecutively enrolled and divided into four groups using FFR ≤0.80 and percent diameter stenosis (%DS) ≥50% as cutoffs for functional and anatomical significance, respectively. Accordingly, FFR >0.80 and DS ≥50%, and FFR ≤0.80 and DS

Toad toxin has digitalis-like cardioactive effects that include bradycardia, varying degrees of atrioventricular block, ventricular tachycardia, ventricular fibrillation and sudden cardiac death. We report here on a 54-year-old man who had varying degrees of atrioventricular block and nonsustained ventricular tachycardia two hours after he ate a bowl of toad soup. (Korean Circulation J 2007;37:283-286)

Background and Objectives: Nitroglycerin-mediated arterial dilation (NMD) was shown to be preserved in most previous studies, and this is possibly due to using a single high dose of nitroglycerin (NTG), which causes maximal arterial dilation. We sought to evaluate the clinical factors of flow-mediated dilation (FMD) and NMD at different doses of NTG in the patients with coronary artery disease (CAD). Subjects and Methods: Thirty-two consecutive patients (mean age: 61 years old, 18 males) with angiographically proven CAD underwent FMD and NMD at total cumulative doses of 25μg, 175μg and 325μg with using high-resolution ultrasound for the imaging. Results: The FMD, NMD (25μg), NMD (175μg) and NMD (325μg) were 4.72±1.82%, 7.08±3.02%, 13.33±6.14% and 15.89±7.24%, respectively (p

Background and Objectives：Rupture-prone plaque, characterized by a large necrotic core, thin fibrous cap and large number of inflammatory cells, is known to be associated with acute coronary syndrome (ACS) from several autopsy and animal studies. We sought to assess in-vivo lesion characteristics of culprit lesions in patients with ACS. Subjects and Methods：One hundred consecutive patients (mean age 60.4 years, 70 males), who underwent percutaneous coronary intervention, were analyzed for intravascular ultrasound (IVUS) radiofrequency information using IVUS-virtual histology (VH) software. Results：Patients with ACS (n=44, mean 59.7 years, 34 males) had a lower prevalence of hypertension (45.5% vs. 67.9%, p=0.024), higher level of high-sensitivity C-reactive protein (0.36±0.36 mg/dL vs. 0.22±0.27, p=0.043), longer lesion length (22.6±8.6 mm vs. 19.3±6.9 mm, p=0.036), and more plaque rupture (63.6% vs. 10.7%, p

Background and Objectives：While the clinical significance of descending thoracic aorta intima-media thickness (DTA-IMT) remains unclear, common carotid IMT (CIMT) is known to be associated with major adverse cardiovascular events (MACE) in patients with atherosclerotic disease. Subjects and Methods：A total of 104 patients (mean age, 59 yrs; 69 male) with angiographically proven coronary atherosclerosis underwent transesophageal echocardiography (TEE) for DTA-IMT measurement and carotid scanning for CIMT measurement. The patients were divided into two groups based on the median IMT value, and they were followed up for cardiovascular events and all-cause mortality for a period of 50±21 months. Results：Patients having a higher DTA-IMT value (n=44, >2.1 mm) had a higher chance of stroke (6.7% vs. 2.8%, p=0.04), peripheral vascular disease (6.7% vs. 1.9%, p=0.02), and death (2.9% vs. 0%, p=0.04) than those who had lower DTA-IMT values (n=60, ≤2.1 mm). The patients who had higher CIMT values (n=49, >0.089 mm) had a higher chance of peripheral vascular disease (16% vs 2%, p= 0.009) than those having lower IMT values (n=55, ≤0.089 mm). However, there was no significant difference between the groups in terms of recurrent chest pain, heart failure, syncope, myocardial infarction or chronic kidney disease during the follow-up period. Multivariate Cox regression analysis revealed that increased DTA-IMT was associated with stroke (OR, 4.29; 95% CI, 1.076-17.181; p=0.039) and peripheral vascular disease (OR, 9.37; 95% CI, 1.571-55.499; p=0.014), whereas increased CIMT was associated with peripheral vascular disease (OR, 14.365; 95% CI, 1.050-196.540; p=0.046). Conclusion：This study suggests that descending thoracic aorta IMT is more closely associated with prognosis in patients with coronary atherosclerosis than CIMT. (Korean Circulation J 2007; 37:365-372)

Background and Objectives:There is little clinical data on the results of using Sirolimus-Eluting Stent (SES) for treating In-Stent Restenosis (ISR). We performed this study to evaluate the clinical outcomes for implanting SES for treating ISR in a real world hospital environment. Subjects and Methods:A total of 30 patients with 32 ISRs (males: 73.3%, mean age: 60.2) (focal lesions: 21.9%, diffuse intra-stent lesions: 34.4%, proliferative lesions: 21.9%, total occlusions: 21.9%) were treated with SES after balloon predilation was performed. We evaluated the clinical results and the performed coronary angiography after 6 months. Results:All the procedures were successful. The mean SES diameter and length were 3.0±0.3 mm and 27.1±5.5 mm, respectively, and the mean acute gain was 2.42±0.38 mm. No in-hospital major adverse cardiac events (MACE) were observed. Twenty five patients with 27 lesions (84.4%) underwent coronary angiography at their 6 month follow-up. The late loss and loss index were 0.41±0.56 mm and 0.18±0.22, respectively. The binary restenosis rate was 7.4% (2/27 lesions). The rate of target lesion revascularization was 3.7% (1/27 lesion). The incidence of MACE at 6 months was 3.3% (1/30 patient). Conclusion:Treating ISR with SES is a safe and effective procedure for reducing ISR without the occurrence of acute or sub-acute thrombosis. (Korean Circulation J 2006;36:121-125)

Background and Objectives:In radiofrequency catheter ablation (RFCA), it is an essential point to understand the characteristics of local electrograms at arrhythmic focus. However controversy exists as whether the unipolar or bipolar electrogram is superior in detecting arrhythmic focus. Subjects and Methods:We evaluated the characteristics of unipolar and bipolar electrograms at ventricular tachycardia (VT) origin. Electroanatomical mapping and RFCA were performed in 6 patients with idiopathic VT. 22 sites were enrolled and 6 of them were successful sites. We analyzed the relationship between surface and local electrograms in accordance with success or failure. We also analyzed the morphology of local electrograms. Results:At successful sites of RFCA, point of unipolar onset (22.86±10.82 msec vs 5.47±26.31 msec, p

Numerous central nervous system disorders can produce various electrocardiographic abnormalities due to vagal stimulation. These common abnormalities may include:QT prolongation, a large and inverted T wave and a prominent U wave etc. Sinus bradycardia and atrioventricular block have rarely been reported. We experienced a case of sick sinus syndrome, which was associated with a subarachnoid hemorrhage and subdural hematoma following a head trauma. (Korean Circulation J 2003;33 (12):1151-1154)

Background:Coronary sinus catheterization is important in electrophysiological studies. However the morphologic feature of the coronary sinus and its significance in patients with supraventricular tachycardia (SVT) have not been determined. During diagnostic electrophysiological studies, coronary sinus catheterization was easier in patients with atrioventricular nodal reentry tachycardia (AVNRT) than in patients with atrioventricular reentry tachycardia (AVRT). Therefore, we studied coronary sinus morphology in patients with SVT and compared AVNRT and AVRT patients. Methods:The size and shape of the coronary sinus were measured in 13 patients who underwent retrograde coronary sinus venogram during electrophysiologic study between May and June 1996. The diagnosis was 7 cases of AVNRT, 2 of Wolff-Parkinson-White syndrome and 4 of concealed bypass tracts (mean age, 40 years:male vs female, 1:1.2). Results:The mean coronary sinus ostial diameter was 10.4±2.0 mm;for AVNRT, it was 11.4±2.2 mm, and for AVRT it was 9.3±1.0 mm in left anterior oblique projection (p=0.031). The mean coronary sinus-to-spine angle was 82.6±17.4°:AVNRT 95.4±24.4° and AVRT 67.7±15.2° in anterior posterior projection (p=0.035). Conclusion:The coronary sinus ostial diameter of AVNRT patients was significantly larger than that of AVRT patients. This finding may have important implications for arrythmia pathogenesis in such patients. (Korean Circulation J 1998;28(4):620-625)