Young Keun On

Sungkyunkwan University, Sŏul, Seoul, South Korea

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Publications (47)115.79 Total impact

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    ABSTRACT: A case of a fistula running from the pulmonary vein to the esophagus after a staged hybrid procedure combining total thoracoscopic ablation and percutaneous radiofrequency catheter ablation has not been reported previously. We describe such a case in a 37-year-old man who was successfully treated by surgery.
    The Korean journal of thoracic and cardiovascular surgery. 12/2014; 47(6):560-2.
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    ABSTRACT: We applied cardiac resynchronization therapy (CRT) for desynchronized heart failure patients. We evaluated clinical outcomes including morbidity, mortality, and echocardiographic parameters in 47 patients with implanted CRT in Korea from October 2005 to May 2013. The combined outcomes of hospitalization from heart failure, heart transplantation and death were the primary end point. Median follow-up period was 17.5 months. The primary outcomes listed above occurred in 10 (21.3%) patients. Two patients (4.3%) died after CRT and 8 (17%) patients were hospitalized for recurrent heart failure. Among patients hospitalized for heart failure, 2 (4.3%) patients underwent heart transplantation. The overall free rate of heart failure requiring hospitalization was 90.1% (95% CI, 0.81-0.99) over one year and 69.4% (95% CI, 0.47-0.91) over 3 yr. We observed improvement of the New York Heart Association classification (3.1±0.5 to 1.7±0.4), decreases in QRS duration (169.1 to 146.9 ms), decreases in left ventricular (LV) end-diastolic (255.0 to 220.1 mL) and end-systolic (194.4 to 159.4 mL) volume and increases in LV ejection fraction (22.5% to 31.1%) at 6 months after CRT. CRT improved symptoms and echocardiographic parameters in a relatively short period, resulting in low mortality and a decrease in hospitalization due to heart failure.
    Journal of Korean Medical Science 12/2014; 29(12):1651-7. · 1.25 Impact Factor
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    ABSTRACT: Purpose: Recurrent syncope leads to poor functional status and psychiatric impairment in patients with syncope. The aim of the study was to prospectively analyze the risk factors attributed to syncope recurrence. Materials and Methods: Between 2009 and 2010, 289 patients with all cause of syncope visited our institution. Syncope recurrences were followed for 1 year by telephone interview every 3 months. Results: We diagnosed 181 (63%) patients with neurally mediated syncope (NMS), 39 (13%) with orthostatic hypotension, 34 (12%) with cardiac syncope, and 35 (12%) with unexplained syncope. During the 1-year follow-up period, 19 (6.6%) patients suffered recurrent syncope. Kaplan-Meier curves showed that recurrent syncope was observed more often in patients with unexplained syncope compared with those with NMS (p < 0.01), and also observed more often in patients with six previous syncopal episodes compared to those with fewer episodes (p = 0.02). Cox regression analysis showed that the recurrence of syncope was significantly associated with more than six previous syncopal episodes (HR 5.38, 95% CI 1.17-24.71, p = 0.03) and that there was a tendency for association between recurrence of syncope and unexplained syncope (HR 6.13, 95% CI 0.96-39.1, p = 0.05). Conclusions: Patients with previous frequent syncopal episodes or unexplained syncope had higher rates of syncope recurrence during the follow up period. © 2014 S. Karger AG, Basel.
    Cardiology 11/2014; 129(4):233-239. · 2.04 Impact Factor
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    ABSTRACT: The selection of the optimal right ventricular (RV) pacing site remains unclear. We hypothesized that a normal paced QRS axis would provide a physiological ventricular activation and lead to a better long-term outcome.
    Journal of Interventional Cardiac Electrophysiology 11/2014; · 1.55 Impact Factor
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    ABSTRACT: Our objective was to compare the efficacy of dronedarone and propafenone in maintaining sinus rhythm in patients with atrial fibrillation (AF) after electrical cardioversion.
    Clinical Therapeutics 08/2014; · 2.59 Impact Factor
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    ABSTRACT: Brugada syndrome is a rare channelopathy associated with the SCN5A gene that causes fatal ventricular arrhythmias. This case of Brugada syndrome, in which ventricular tachycardia (VT) was provoked by high fever, is the first report in a Korean child. The boy had retinoblastoma of his left eye diagnosed at 16 months of age. After chemotherapy, he contracted a catheter-related infection with a high fever up to 41℃ leading to monomorphic VT. This was characterized as having right bundle branch block morphology, superior axis deviation, and a heart rate of 212/min. Direct current cardioversion recovered the VT to sinus rhythm after a lack of response to amiodarone and lidocaine. A second attack of VT that was not controlled by cardioversion, however, responded to lidocaine. The baseline electrocardiogram showed a long PR interval and QRS duration, and the patient's grandfather had a history of Brugada syndrome. A mutation in SCN5A was identified in this patient, his father, and his grandfather. The patient was treated with quinidine and followed up for 1 year.
    Korean Journal of Pediatrics 08/2014; 57(8):374-8.
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    ABSTRACT: Percutaneous left atrial appendage (LAA) occlusion using the Watchman device is suggested as an alternative modality to warfarin for stroke prevention in patient with nonvalvular atrial fibrillation. However, peri-device leakage due to incomplete LAA occlusion remains one of the most frequent limitations. Herein, we report a case of progressive increase in peri-device leakage after the Watchman device implantation on long-term transesophageal echocardiographic follow-up accompanied by stroke.
    The Canadian journal of cardiology 06/2014; · 3.94 Impact Factor
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    ABSTRACT: Atrial septal defect (ASD) is one of the most common congenital heart defects in adults. Surgical repair is the most common treatment approach, but device closure has recently become widely performed in accordance with the trend toward less invasive surgical approaches. Although surgery is recommended when ASD is accompanied by atrial fibrillation, this study reports a case in which a complete cure was achieved by closure of a device and totally thoracoscopic ablation.
    The Korean journal of thoracic and cardiovascular surgery. 06/2014; 47(3):280-2.
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    ABSTRACT: Background: Although the maze procedure reduces the risk of adverse cardiac events, the clinical importance of post-maze left atrial (LA) activity on long-term surgical outcomes is not well defined. Methods and Results: Between January 2000 and December 2009, 416 consecutive patients with sinus conversion after a modified Cox III procedure with cryoablation were enrolled and subdivided into patients with restored LA activity (group ReA; n=231) and those without LA activity (group NoA; n=185) assessed using Doppler echocardiographic examination at 3-6 months after the maze procedure. During the long-term follow-up (4.6±2.6 years), the NoA group showed more frequent major adverse events (P=0.001) including cardiac death (P=0.145), heart failure events (P=0.032), and thromboembolic stroke (P=0.048) than the ReA group. In multivariate analysis, lack of LA activity was associated with a 2.2-fold increased risk for major adverse events (95% confidence interval [CI], 1.1-6.8; P=0.029) and with a 2.4-fold increased risk for late progression of tricuspid regurgitation (95% CI, 1.0-3.5; P=0.041). Conclusions: Absence of LA activity after the maze procedure was independently associated with a significantly increased risk of major adverse events and late progression of tricuspid regurgitation.
    Circulation Journal 04/2014; · 3.69 Impact Factor
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    ABSTRACT: Cardiac autonomic dysfunction reportedly contributes to the AF triggering and maintenance. Heart rate turbulence (HRT) is a promising noninvasive measure of cardiac autonomic function. We investigated whether ambulatory ECG-based HRT measurement could predict in-hospital new-onset atrial fibrillation (AF) after coronary artery bypass graft (CABG) surgery. HRT onset (TO) and slope (TO) were prospectively measured from 24-h Holter recording in 113 consecutive patients prior to CABG. Abnormal HRT was defined as at least one abnormal value in TO (>0%) and TS (<2.5ms/RR). Patients with abnormal HRT (n=60) showed a significantly higher AF incidence (47% versus 21%, P=0.005) and AF burden (29±9 versus 7±5h, P=0.043) than those with normal HRT (n=53). Abnormal HRT were identified as independent predictors for the new-onset postoperative AF. During the follow-up period (12.0±10.5months), the abnormal HRT group showed a worse prognosis versus the normal HRT group regarding the AF recurrence/postoperative stroke (P=0.018). Additionally, the postoperative AF incidence, in-hospital AF burden, and the rate of AF recurrence/postoperative stroke gradually elevated as the number of abnormal HRT values increased from 0 to 2. Preoperative abnormal HRT was significantly associated with worse short-term (in-hospital new-onset AF) and long-term outcomes (post-discharge AF recurrence/postoperative stroke) after CABG surgery. Additional studies incorporating preventive interventions depending on the preoperative HRT results might be worthwhile in this patient group.
    International journal of cardiology 04/2014; · 6.18 Impact Factor
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    ABSTRACT: Purpose: Our study aims to analyze prognosis after implantable cardioverter-defibrillator (ICD) implantation in Korean patients with Brugada syndrome (BrS). Materials and Methods: This was a retrospective study of BrS patients implanted with an ICD at one of four centers in Korea between January 1998 and April 2012. Sixty-nine patients (68 males, 1 female) were implanted with an ICD based on aborted cardiac arrest (n=38, 55%), history of syncope (n=17, 25%), or induced ventricular tachyarrhythmia on electrophysiologic study in asymptomatic patients (n=14, 20%). A family history of sudden cardiac death and a spontaneous type 1 electrocardiography (ECG) were noted in 13 patients (19%) and 44 patients (64%), respectively. Results: During a mean follow-up of 59±46 months, 4.6±5.5 appropriate shocks were delivered in 19 patients (28%). Fourteen patients (20%) experienced 5.2±8.0 inappropriate shocks caused by supraventricular arrhythmia, lead failure, or abnormal sensing. Six patients were admitted for cardiac causes during follow-up, but no cardiac deaths occurred. An episode of aborted cardiac arrest was a significant predictor of appropriate shock, and the composite of cardiac events in the Cox proportional hazard model [hazard ratio (95% confidence interval) was 11.34 (1.31-97.94) and 4.78 (1.41-16.22), respectively]. However, a spontaneous type 1 ECG was not a predictor of cardiac events. Conclusion: Appropriate shock (28%) and inappropriate shock (20%) were noted during a mean follow-up of 59±46 months in Korean BrS patients implanted with an ICD. An episode of aborted cardiac arrest was the most powerful predictor of cardiac events.
    Yonsei medical journal 01/2014; 55(1):37-45. · 0.77 Impact Factor
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    ABSTRACT: Atrial fibrillation (AF) is the most common arrhythmia. Gain-of-function mutations in KCNQ1, the pore-forming α-subunit of the slow delayed rectifier K current (I Ks) channel, have been associated with AF. The purpose of this study was functional assessment of a mutation in KCNQ1 identified in a family with persistent AF and sinus bradycardia. We investigated whether this KCNQ1 missense mutation could form the genetic basis for AF and bradycardia simultaneously in this family. Sanger sequencing in a family with hereditary persistent AF identified a novel KCNQ1 variant (V241F) in a highly conserved region of S4 domain. The proband and her son developed bradycardia and persistent AF in an age-dependent fashion. The other son was a mutation carrier but he showed sinus bradycardia and not AF. Whole-cell patch clamp electrophysiology showed that V241F mutation in KCNQ1 shifted the activation curve to the left and dramatically slowed deactivation, leading to a constitutively open-like phenotype. Computer modeling showed that V241F would slow pacemaker activity. Also, simulations of atrial excitation predicted that V241F results in extreme shortening of action potential duration, possibly resulting in AF. Our study indicates that V241F might cause sinus bradycardia by increasing I Ks. Additionally, V241F likely shortens atrial refractoriness to promote a substrate for reentry. KCNQ1 mutations have previously been described in AF, yet this is the first time a mutation in KCNQ1 is associated with age-dependent bradycardia and persistent AF. This finding further supports the hypothesis that sinus node dysfunction contributes to the development of AF.
    Pflügers Archiv - European Journal of Physiology 08/2013; · 4.87 Impact Factor
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    ABSTRACT: Mutation or common intronic variants in cardiac ion channel genes have been suggested to be associated with sudden cardiac death caused by idiopathic ventricular tachyarrhythmia. This study aimed to find mutations in cardiac ion channel genes of Korean sudden cardiac arrest patients with structurally normal heart and to verify association between common genetic variation in cardiac ion channel and sudden cardiac arrest by idiopathic ventricular tachyarrhythmia in Koreans. Study participants were Korean survivors of sudden cardiac arrest caused by idiopathic ventricular tachycardia or fibrillation. All coding exons of the SCN5A, KCNQ1, and KCNH2 genes were analyzed by Sanger sequencing. Fifteen survivors of sudden cardiac arrest were included. Three male patients had mutations in SCN5A gene and none in KCNQ1 and KCNH2 genes. Intronic variant (rs2283222) in KCNQ1 gene showed significant association with sudden cardiac arrest (OR 4.05). Four male sudden cardiac arrest survivors had intronic variant (rs11720524) in SCN5A gene. None of female survivors of sudden cardiac arrest had SCN5A gene mutations despite similar frequencies of intronic variants between males and females in 55 normal controls. Common intronic variant in KCNQ1 gene is associated with sudden cardiac arrest caused by idiopathic ventricular tachyarrhythmia in Koreans.
    Journal of Korean medical science 07/2013; 28(7):1021-6. · 0.84 Impact Factor
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    ABSTRACT: Atrial fibrillation (AF) is the most common chronic arrhythmia in the world, and it is associated with an increased long-term risk of stroke, heart failure, and all-cause mortality. To overcome the limitations of transvenous radiofrequency (RF) ablation for AF, total thoracoscopic ablation (TTA) has evolved as a new technique. TTA has several advantages over transvenous RF ablation and is known to produce better outcomes, especially in patients with persistent AF. Herein, we report 2 cases of successful TTA followed by an electrophysiological study confirming satisfactory ablation lines; the first such procedure reported in Korea.
    Korean Circulation Journal 06/2013; 43(6):422-5.
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    ABSTRACT: Purpose: Several studies have demonstrated that psychiatric disorders such as anxiety, depression and panic attack are associated with syncope, especially vasovagal and unexplained syncope (US). The aim of this study was to compare the prevalence of anxiety and depression between patients with neurally mediated syncope (NMS) and US and to investigate the clinical factors associated with anxiety and depression. Materials and Methods: Between January 2009 and March 2010, 383 patients with syncopal episodes completed a Hospital Anxiety and Depression Scale questionnaire to assess symptoms of anxiety and depression. Inclusion criteria were NMS and US. Exclusion criteria were cardiac syncope, orthostatic hypotension and other disorders mimicking syncope. After exclusion, 199 patients were included. Results: There were 176 (88.4%) NMS patients and 23 (11.6%) US patients. The prevalence of abnormal anxiety and depression were not significantly different between the NMS and US groups (10.2% vs. 8.7%, p=0.99; 8.5% vs. 17.4%, p=0.24). Clinical factors associated with anxiety were female gender (p=0.01) and six or more recurrent syncopal episodes (p=0.01) by univariate analysis. The only factor associated with abnormal anxiety score (OR=20.26, 95% CI: 1.4-291.6, p=0.01) was more than six recurrent syncopal episodes, while a positive head-up tilt table testing response was inversely associated with abnormal depression score (OR=0.28, CI: 0.08-0.97, p=0.04) in the multiple logistic regression analysis. Conclusion: Anxiety was associated with frequent syncopal episodes. Thus, anxiety might be considered in the management of syncope patients.
    Yonsei medical journal 05/2013; 54(3):583-9. · 0.77 Impact Factor
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    ABSTRACT: Purpose: The mechanisms underlying syncope remain unknown in about 20% of patients with recurrent syncope. The implantable loop recorder (ILR) has been shown to be a useful diagnostic tool in patients with unexplained syncope even after negative initial evaluations. Nevertheless, ILR has rarely been used in clinical practice. Materials and Methods: This study included 18 consecutive patients who had an ILR implanted at our center because of recurrent unexplained syncope after extensive diagnostic tests between February 2006 and June 2011. Results: Diagnosis was confirmed in 10 (55.6%) of the 18 enrolled patients (13 males, 61±15 years). The confirmed diagnoses included sick sinus syndrome (n=6, 60%), advanced atrioventricular block (n=2, 20%) and ventricular tachyarrhythmia (n=2, 20%). The mean follow-up durations of the total study subjects and the diagnosed patients were 11.3±10.6 months and 5.6±9.2 months, respectively. Of the 10 diagnosed patients, 8 (80%) were diagnosed within 6 months of loop recorder implantation. Conclusion: ILR may be a valuable and effective diagnostic tool for patients with unexplained syncope.
    Yonsei medical journal 05/2013; 54(3):590-5. · 0.77 Impact Factor
  • International journal of cardiology 04/2013; · 6.18 Impact Factor
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    ABSTRACT: The maze procedure for atrial fibrillation (AF) is effective in restoring sinus rhythm; however, a significant proportion of patients failed to recover atrial mechanical contraction (AMC). We hypothesized that preoperative atrial fibrotic activity would be related to the AMC recovery. In atrial tissues of 128 consecutive patients who underwent mitral valve and combined maze surgery using cryoablation for persistent AF, preoperative mRNA levels of various biomarkers were measured including transforming growth factor-β1 (TGF-β1), atrial natriuretic peptide, brain natriuretic peptide (BNP), C-reactive protein, connective tissue growth factor, matrix metalloproteinase, N-terminal prohormone BNP, and tissue inhibitor of metalloproteinase. Presence of AMC was assessed using Doppler echocardiographic measurement of the transmitral A-wave velocity. At 1-year follow-up, patients without AMC (n=62) showed higher preoperative TGF-β1 mRNA expression (0.42 versus 0.28, P=0.01) than those with AMC (n=66). There was no significant difference between the two groups regarding the other biomarkers. Recovery rate of AMC and the increment of A-wave velocity were reduced with the increase of preoperative TGF-β1 mRNA level. Multiple logistic regression analysis revealed that TGF-β1 mRNA levels were independently associated with the absence of AMC (odds ratio 7.47, 95% CI 1.63 to 34.4, P=0.01). TGF-β1-mediated atrial fibrotic activity might exert a detrimental effect on the reversibility of atrial mechanical contraction after the maze and combined mitral valve surgery for long-standing persistent AF. Earlier surgical intervention might be needed to preserve atrial mechanical function.
    International journal of cardiology 04/2013; 164(2):232-7. · 6.18 Impact Factor
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    ABSTRACT: Prolongations of PR interval and QRS duration on 12-lead electrocardiogram are associated with atrioventricular and interventricular/intraventricular dyssynchrony, respectively. However, their clinical significance remains unclear in real-world heart failure (HF) population. We assessed whether the presence of first-degree atrioventricular block and/or QRS prolongation (≥120 ms) is associated with worse short- and long-term outcomes in patients with acute HF. The Korean Heart Failure is a nationwide registry of 3,200 consecutive patients presenting with acute HF at 24 centers in South Korea between June 2004 and April 2009. We selected 1,986 patients with sinus rhythm and divided them into 4 groups depending on the presence of first-degree atrioventricular block and/or QRS prolongation; ED_Neither (n = 1,347), ED_PR (n = 217), ED_QRS (n = 329), and ED_Both (n = 93) groups, respectively. During the median follow-up of 18.2 months, overall death rate (17%, 22%, 20%, and 29%, P < .01) tended to rise with increasing number of electrical dyssynchrony markers. Patients in ED_Both group showed worst outcomes regarding the requirement of invasive managements during the index admission, in-hospital mortality, postdischarge death/rehospitalization, and cardiac device implantation. In time-dependent Cox regression analyses, presence of both PR >200 ms and QRS ≥120 ms was independently associated with in-hospital death (P < .01), postdischarge death/rehospitalization (P = .03), cardiac device implantation (P < .01), and overall death (P < .01). A combined analysis of electrical dyssynchrony markers (PR prolongation and QRS widening) might be useful for short- and long-term risk stratifications of patients with acute HF.
    American heart journal 01/2013; 165(1):57-64.e2. · 4.56 Impact Factor
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    ABSTRACT: Background: Brugada syndrome (BrS) is characterized by specific alterations on ECG in the right precordial leads and associated with ventricular arrhythmia that may manifest as syncope or sudden cardiac death. The major causes of BrS are mutations in SCN5A for a large subunit of the sodium channel, Nav1.5, but a mutation in SCN3B for a small subunit of sodium channel, Navβ3, has been recently reported in an American patient. Methods and Results: A total of 181 unrelated BrS patients, 178 Japanese and 3 Koreans, who had no mutations in SCN5A, were examined for mutations in SCN3B by direct sequencing of all exons and adjacent introns. A mutation, Val110Ile, was identified in 3 of 178 (1.7%) Japanese patients, but was not found in 480 Japanese controls. The SCN3B mutation impaired the cytoplasmic trafficking of Nav1.5, the cell surface expression of which was decreased in transfected cells. Whole-cell patch clamp recordings of the transfected cells revealed that the sodium currents were significantly reduced by the SCN3B mutation. Conclusions: The Val110Ile mutation of SCN3B is a relatively common cause of SCN5A-negative BrS in Japan, which has a reduced sodium current because of the loss of cell surface expression of Nav1.5.
    Circulation Journal 12/2012; · 3.69 Impact Factor