Shih-Ann Chen

National Yang Ming University, T’ai-pei, Taipei, Taiwan

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Publications (374)1511.65 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Renal dysfunction is a significant risk factor of ischemic stroke in atrial fibrillation (AF). However, the incidence of ischemic stroke and how to predict its occurrence amongst AF patients with end-stage renal disease (ESRD) are unclear.
    Heart rhythm: the official journal of the Heart Rhythm Society 06/2014; · 4.56 Impact Factor
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    ABSTRACT: Fibroblast growth factor (FGF)-23 is a key regulator of phosphate homeostasis. Higher FGF-23 levels are correlated with poor outcomes in cardiovascular diseases. FGF-23 can produce cardiac hypertrophy and increase intracellular calcium, which can change cardiac electrical activity. However, it is not clear whether FGF-23 possesses arrhythmogenic potential through calcium dysregulation. Therefore, the purposes of this study were to evaluate the electrophysiological effects of FGF-23 and identify the underlying mechanisms.
    European Journal of Clinical Investigation 06/2014; · 3.37 Impact Factor
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    ABSTRACT: Radiofrequency catheter ablation (RFCA) is an effective therapeutic strategy in eliminating drug-refractory idiopathic right ventricular outflow tract ventricular arrhythmias (RVOT VAs). It remains unclear what factors influence early and late VA recurrences after ablation.
    Heart rhythm: the official journal of the Heart Rhythm Society 06/2014; · 4.56 Impact Factor
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    ABSTRACT: Ventricular arrhythmias commonly originate from the right ventricular out-flow tract (RVOT). However, the electrophysiological characteristics and Ca(2+) homoeostasis of RVOT cardiomyocytes remain unclear. Whole-cell patch clamp and indo-1 fluorometric ratio techniques were used to investigate action potentials, Ca(2+) homoeostasis and ionic currents in isolated cardiomyocytes from the rabbit RVOT and right ventricular apex (RVA). Conventional microelectrodes were used to record the electrical activity before and after (KN-93, a Ca(2+) /calmodulin-dependent kinase II inhibitor, or ranolazine, a late sodium current inhibitor) treatment in RVOT and RVA tissue preparations under electrical pacing and ouabain (Na(+) /K(+) ATPase inhibitor) administration. In contrast to RVA cardiomyocytes, RVOT cardiomyocytes were characterized by longer action potential duration measured at 90% and 50% repolarization, larger Ca(2+) transients, higher Ca(2+) stores, higher late Na(+) and transient outward K(+) currents, but smaller delayed rectifier K(+) , L-type Ca(2+) currents and Na(+) -Ca(2+) exchanger currents. RVOT cardiomyocytes showed significantly more pacing-induced delayed afterdepolarizations (22% versus 0%, P < 0.05) and ouabain-induced ventricular arrhythmias (94% versus 61%, P < 0.05) than RVA cardiomyocytes. Consistently, it took longer time (9 ± 1 versus 4 ± 1 min., P < 0.05) to eliminate ouabain-induced ventricular arrhythmias after application of KN-93 (but not ranolazine) in the RVOT in comparison with the RVA. These results indicate that RVOT cardiomyocytes have distinct electrophysiological characteristics with longer AP duration and greater Ca(2+) content, which could contribute to the high RVOT arrhythmogenic activity.
    Journal of Cellular and Molecular Medicine 06/2014; · 4.75 Impact Factor
  • Shih-Lin Chang, Shih-Ann Chen
    Journal of the Chinese Medical Association : JCMA. 06/2014;
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    ABSTRACT: Signal averaged electrocardiogram (SAECG) is a specific and non-invasive tool useful for arrhythmogenic right ventricular cardiomyopathy (ARVC) diagnosis. However, its role in risk stratification of patients with ARVC remains largely undefined. Sixty-four patients fulfilling Task Force ARVC criteria (mean age: 47±14years-old, 56% male, 50% definite ARVC) were enrolled. The baseline demographic, electrocardiographic, structural, and electrophysiological characteristics were collected. Patients with SAECG fulfilling all 3 Task Force criteria (3+ SAECG) were categorized into group 1, and those fulfilled 2 or less criterion were categorized into group 2. The study endpoints were unstable ventricular arrhythmia (VA), device detectable sustained fast VA (cycle lengths <240ms) and cardiovascular death. During a mean follow-up of 21±20months, 15 primary endpoints including 12 unstable VAs and 3 device-detected fast VAs were met. One patient died of electrical storm, and one patient underwent heart transplantation. The presence of 3+ SAECG predicted malignant events in all patients with definite and non-definite ARVC (p<0.01, OR=30.5, 95% CI=2.5-373.7) and in patients with definite ARVC alone (p=0.03, OR=11.1, 95% CI=1.3-93.9). Patients diagnosed with non-definite ARVC without 3+ SAECG were free from malignant events. SAECG fulfilling all 3 Task Force criteria was an independent risk predictor of malignant events in ARVC patients. SAECG may play a valuable role in ARVC risk stratification.
    International journal of cardiology 04/2014; · 7.08 Impact Factor
  • Article: AF News.
    Tze-Fan Chao, Li-Wei Lo, Shih-Ann Chen
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    ABSTRACT: Warfarin use and the risk for stroke and bleeding in patients with atrial fibrillation undergoing dialysis. Shah M et al., McGill University Health Center, Montreal, Quebec, Canada. Circulation. 2014, [Epub ahead of print]. PMID: 24452752. This article is protected by copyright. All rights reserved.
    Journal of Cardiovascular Electrophysiology 04/2014; · 3.48 Impact Factor
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    ABSTRACT: Sinoatrial node (SAN) dysfunction increases the occurrences of atrial fibrillation (AF). The pulmonary veins (PVs) play a critical role in the pathophysiology of AF. The purpose of this study was to evaluate whether SAN electrical activity can modulate PV arrhythmogenesis. Conventional microelectrodes and multi-electrode array system were used to simultaneously record the electrical activity and conduction properties of rabbit SAN and PV tissue preparations with and without SAN-PV interruptions before and after perfusion with Anemonia sulcata toxin (ATX)-II (100nM) or isoproterenol (1μM). ATX-II significantly increased PV beating rates, which overdrove SAN electrical activity with the occurrences of PV burst firings in 5 (56%) of 9 tissue preparations, and induced SAN-PV conduction block in 6 (67%) of 9 preparations. After SAN-PV disconnection, ATX-II induced burst firing and early afterdepolarizations in 8 (89%) of 9 PVs. Moreover, the multi-electrode array found that ATX-II reversed the electrical conduction between the SAN and PV with an increase in electrical activity from 1.8±0.6 to 2.9±0.6Hz (P<0.05) in SAN-PV preparations (n=7). In contrast, isoproterenol did not reverse electrical conduction between the SAN and PV with an increase in electrical activity from 1.8±0.2 to 3.0±0.3Hz (P<0.005) in SAN-PV preparations (n=7). SAN electrical activity modulates PV arrhythmogenesis. SAN-PV conduction blocks can increase PV arrhythmogenesis.
    International journal of cardiology 03/2014; · 7.08 Impact Factor
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    ABSTRACT: The use of SPECT phase analysis to optimize left-ventricular (LV) lead positions for cardiac resynchronization therapy (CRT) was performed at baseline, but CRT works as simultaneous right ventricular (RV) and LV pacing. The aim of this study was to assess the impact of RV apical (RVA) pacing on optimal LV lead positions measured by SPECT phase analysis. This study prospectively enrolled 46 patients. Two SPECT myocardial perfusion scans were acquired under sinus rhythm with complete left bundle branch block and RVA pacing, respectively, following a single injection of (99m)Tc-sestamibi. LV dyssynchrony parameters and optimal LV lead positions were measured by the phase analysis technique and then compared between the two scans. The LV dyssynchrony parameters were significantly larger with RVA pacing than with sinus rhythm (p ~0.01). In 39 of the 46 patients, the optimal LV lead positions were the same between RVA pacing and sinus rhythm (kappa = 0.861). In 6 of the remaining 7 patients, the optimal LV lead positions were along the same radial direction, but RVA pacing shifted the optimal LV lead positions toward the base. The optimal LV lead positions measured by SPECT phase analysis were consistent, no matter whether the SPECT images were acquired under sinus rhythm or RVA pacing. In some patients, RVA pacing shifted the optimal LV lead positions toward the base. This study supports the use of baseline SPECT myocardial perfusion imaging to optimize LV lead positions to increase CRT efficacy.
    European Journal of Nuclear Medicine 02/2014; · 4.53 Impact Factor
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    ABSTRACT: Background: Spectral analysis of the left atrium can identify high dominant frequency (DF) sites, which might play a role in the perpetuation of atrial fibrillation (AF). Furthermore, the role of the cardiac autonomic nervous system (CANS) in the genesis of AF has been demonstrated. The relationship between CANS and the high-DF sites (AF nest) was the aim of the investigation. Methods and Results: In 12 dogs, high frequency stimulation was applied to locate 4 major left atrial (LA) ganglionated plexi (GPs). An Ensite Array and a mapping catheter were delivered into the left atrium for electroanatomical mapping. During sinus rhythm, spectral analysis was performed on the bipolar electrograms in the left atrium before and after epicardial GP ablation. The majority of AF nests were close to the GPs (52±18% of total AF nests). After GP ablation, the mean LA DF values decreased from 54±7Hz to 49±4Hz (P=0.023), and DF values of the AF nest decreased from 93±2Hz to 87±4Hz (P=0.001). Most of the previous AF nest sites close to the GPs disappeared (85±23%). The surface area of the AF nest decreased from 9±5cm(2) to 3±2cm(2) (P=0.001). Conclusions: Catheter ablation of the GP decreased the DF values, AF nest areas and diminished the number of AF nests; particularly those close to the GPs, indicating that the CANS might play an important role in the mechanism of the AF nest.
    Circulation Journal 02/2014; · 3.58 Impact Factor
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    ABSTRACT: Background: The impact of renal dysfunction has been investigated in patients with non-valvular atrial fibrillation (AF). The aim of this study was to assess its additive prognostic value in low thromboembolic risk AF patients with CHA2DS2-VASc score 0-1. Methods and Results: A total of 617 non-valvular AF patients were enrolled and baseline serum creatinine was measured. Estimated glomerular filtration rate and estimated clearance of creatinine were calculated using the Modification of Diet in Renal Disease equation and Cockcroft-Gault formula, respectively. The primary endpoint was cardiovascular death and systemic thromboembolic events, including acute ischemic stroke, transient ischemic attack, and peripheral artery embolism. Of these, 338 individuals had clinical CHA2DS2-VASc score 0-1. Among these individuals, 23 patients had impaired renal function. During the follow-up period of 53.6±32.1 months, the annual composite outcome rate in AF patients with CHA2DS2-VASc score 0-1 was 0.40%/year. As compared with patients with preserved renal function, the annual composite outcome rate was significantly higher in patients with impaired renal function (2.92%/year vs. 0.21%/year, P<0.001). Moreover, on multivariate Cox regression analysis, renal dysfunction was the only risk predictor in these low-risk patients. Conclusions: Impaired renal function has an additive prognostic value for thromboembolic events and cardiovascular mortality in low-risk AF patients with CHA2DS2-VASc score 0-1.
    Circulation Journal 02/2014; · 3.58 Impact Factor
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    ABSTRACT: Background The incidence and risk factors of amiodarone-induced thyroid dysfunction are variable in the literature. Objective The aim of this study was to investigate the clinical and biochemical features and risk factors of amiodarone-induced thyroid dysfunction in Taiwan. Setting This study was conducted at a tertiary referral center for arrhythmia. Method Retrospective analysis of patients treated with amiodarone during the years 2008-2009 was performed. Main outcome measure Incidence and risk factors of amiodarone-induced thyrotoxicosis (AIT) and amiodarone-induced hypothyroidism (AIH) were assessed. Results Of the 527 patients, 437 (82.9 %) remained euthyroid, 21 (4.0 %) developed AIT, and 69 (13.1 %) were affected with AIH. In univariate analysis, AIT was associated with younger age, and the risk factors for AIH included older age, higher baseline thyroid stimulating hormone (TSH) titer, lower baseline free T4 level, lower cumulative amiodarone dosage, and shorter amiodarone treatment duration. Cox regression analysis was performed to determine the different risk categories in the elderly population of age 65-74 (young-old), 75-84 (old-old), and ≥85 years old (oldest-old). Additionally increased risk of AIH was found in the groups of old-old (HR 2.09, 95 % CI 1.11-3.96) and oldest-old (HR 2.57, 95 % CI 1.21-4.75). In the multivariate analysis of risk factors for AIH, baseline TSH level (HR 1.38, 95 % CI 1.12-1.70) and cumulative amiodarone dosage (HR 0.95, 95 % CI 0.93-0.97) remained statistically significant. Conclusion AIH was much more common than AIT in Taiwan, an area with sufficient iodine intake. Higher baseline TSH level was the predominant independent risk factor for the development of AIH.
    International journal of clinical pharmacy. 02/2014;
  • International journal of cardiology 01/2014; · 7.08 Impact Factor
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    ABSTRACT: Pericardial fat (PCF) may induce local inflammation and subsequent structural remodeling of the left atrium (LA). However, the adverse effects of PCF on LA are difficult to be evaluated and quantified. The atrial electromechanical interval determined by transthoracic echocardiogram was shown to be a convenient parameter which can reflect the process of LA remodeling. The goal of the present study was to investigate the association between the electromechanical interval and PCF.
    PLoS ONE 01/2014; 9(5):e97472. · 3.73 Impact Factor
  • Shih-Lin Chang, Shih-Ann Chen
    Journal of the Chinese Medical Association 01/2014; · 0.75 Impact Factor
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    ABSTRACT: Background Renal dysfunction is a significant risk factor of ischemic stroke in atrial fibrillation (AF). However, the incidence of ischemic stroke and how to predict its occurrence amongst AF patients with end-stage renal disease (ESRD) are unclear. Objective The goal of the present study was to compare the CHADS2 and CHA2DS2-VASc scores for stroke risk stratification in AF patients with ESRD. Methods A total of 10,999 AF patients with ESRD undergoing renal replacement therapy who were not receiving oral anticoagulants or antiplatelet agents were identified from Taiwan’s National Health Insurance Research Database. The study endpoint was occurrence of ischemic stroke. Results The median (IQR) CHADS2 and CHA2DS2-VASc scores for the study cohort were 3 (2-5) and 5 (4-7), respectively. During the follow-up, 1,217 patients (11.7%) experienced ischemic stroke, with an incidence rate of 6.9 per 100 person-years. In Cox regression models, the CHADS2 and CHA2DS2-VASc scores were both significant predictors of ischemic stroke. C-indexes for CHADS2 and CHA2DS2-VASc were 0.608 and 0.682, respectively (p<0.001). CHA2DS2-VASc improved the net reclassification index by 4.8% compared with CHADS2 (p<0.0001). Among 1,409 patients with a CHADS2 score of 0 or 1, the CHA2DS2-VASc score ranged from 1 to 4, with event rates ranging from 2.1 to 4.7 per 100 person-years. Conclusions The CHA2DS2-VASc score was useful in predicting ischemic stroke in AF patients with ESRD undergoing dialysis, and was superior to CHADS2. The net clinical benefit balancing stroke reduction against major bleeding with anticoagulation in these high risk patients remains to be defined.
    Heart Rhythm. 01/2014;
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    ABSTRACT: Background A new risk model, the R2CHADS2 score, was proposed to be a powerful scoring scheme in predicting stroke or systemic embolism in atrial fibrillation (AF). The goal of the present study is to validate the usefulness of R2CHADS2 score among AF patients after catheter ablations. We also aimed to compare the accuracies of the CHA2DS2-VASc and R2CHADS2 scores for risk stratifications of thromboembolic (TE) events after ablation procedures. Methods We enrolled a total of 526 patients with AF who underwent catheter ablation. The clinical endpoint was the occurrence of TE events (ischemic stroke, transient ischemic attack, or other systemic embolisms) during the post-ablation follow-up. Results During a follow-up of 37.5+21.3 months, 14 patients (2.7%) experienced TE events. The R2CHADS2 score was an independent predictor of TE events in the multivariate analysis. Patients with a R2CHADS2 score of > 2 had a higher event rate compared to those with a score of 0 or 1 (0.5% versus 7.7%). The areas under the ROC curves of CHA2DS2-VASc and R2CHADS2 scores in predicting TE events were 0.832 and 0.872, respectively. The difference between these 2 curves did not reach statistical significance (p value = 0.338). In addition, the R2CHADS2 score did not improve net stroke risk reclassification over the CHA2DS2-VASc score (net reclassification improvement = -0.9%, p value = 0.948). Conclusions The R2CHADS2 and CHA2DS2-VASc scores could be used to predict TE events for AF patients receiving catheter ablations. The predictive accuracies of both scores were similar in this relatively small-sized cohort undergoing ablation.
    The Canadian journal of cardiology 01/2014; · 3.12 Impact Factor
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    ABSTRACT: Background Digoxin and related cardiac glycoside have been used for almost 100 years in atrial fibrillation (AF). However, recent 2 analyses of the “AFFIRM” trial showed non-consistent results about the risk of mortality associated with digoxin use. The goal of the present study is to investigate the relationship between digoxin and the risk of ischemic stroke and mortality in Asians. Methods This study used the “National Health Insurance Research Database” in Taiwan. A total of 4,781 AF patients who did not receive any antithrombotic therapy were selected as the study population. Among the study population, 829 subjects (17.3%) received the digoxin treatment. The risks of ischemic stroke and mortality of patients with or without digoxin use were compared. Results The use of digoxin was associated with an increased risk of clinical events with an adjusted hazard ratio of 1.41 (95% CI =1.17-1.70) for ischemic stroke and 1.21 (95% CI =1.01-1.44) for all-cause mortality. In the subgroup analysis based on the coexistence with heart failure or not, digoxin was a risk factor of adverse events for patients without heart failure, but not for those with heart failure (interaction p<0.001 for either endpoint). Among AF patients without heart failure, the use of beta-blockers was associated with better survival with an adjusted hazard ratio of 0.48 (95% CI = 0.34-0.68). Conclusions Digoxin should be avoided for AF patients without heart failure since it was associated with an increased risk of clinical events. Beta-blockers may be a better choice for controlling ventricular rate.
    The Canadian journal of cardiology 01/2014; · 3.12 Impact Factor
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    ABSTRACT: Background Radiofrequency catheter ablation (RFCA) is an effective therapeutic strategy in eliminating drug-refractory idiopathic right ventricular outflow tract ventricular arrhythmias (RVOT VAs). It remains unclear what factors influence early and late VA recurrences after ablation. Objectives The aim of our study was to elucidate the differences between early and late recurrences after acute successful RFCA of RVOT VAs in a long-term follow-up. Methods A total of 220 patients with acute successful RFCA of RVOT VAs were enrolled. Detailed clinical characteristics and assessments by non-invasive and invasive electrophysiological studies were explored to predict the overall, early (≤ 1 year), and late VA recurrences (>1 year). Results During a mean follow-up of 34.15±33.74 months, 45 of the 220 patients (20.5%) documented recurrence of RVOT VAs after initial RFCA. Of them, 26 (57.8%) recurrent VA showed similar morphology, and 19 (42.2%) were different. Patients with recurrent VAs were associated with higher incidence of hypertension, higher systolic BP, identification of foci by pacemapping alone, shorter earliest activation time, more RF pulses required, and VA originating from anterior free wall. Multivariate analysis demonstrated that mapping strategy and shorter earliest activation time preceding VA were associated with early recurrences (P<0.001, HR:2.26, 95% CI: 1.49~3.42; P=0.008, HR:0.91, 95% CI: 0.85~0.98, respectively), whereas hypertension was associated with late recurrence (P=0.001, HR:3.48, 95% CI: 1.34~9.07). Conclusion RFCA is an effective strategy in elimination of RVOT VAs. However, early and late recurrences occur commonly. Patients with early and late VA recurrences demonstrated non-uniform patterns of clinical characteristics and electrophysiological properties.
    Heart Rhythm. 01/2014;
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    ABSTRACT: Background The implantation of permanent pacemaker (PPM) is life-saving for patients with life-threatening bradycardia. However, the effectiveness and prognosis of PPM implantations for extremely old patients (> 90 years old) have not been investigated before. Methods From 2001-2012, a total of 108 patients older than 90 years were identified from 2,630 consecutive patients receiving PPM implantations in our hospital as the study group. For each study patient, four age-, gender- and comorbidity-matched subjects who did not have the diagnoses of bradyarrhythmias indicated for PPM implantations were selected from the “Taiwan National Health Research Database” to constitute the control group (n = 432). The study endpoint was all-cause mortality. Results The median age of the study population was 91 (inter-quartile range = 90-93) years. Among the PPM group, 45 patients died during the follow-up with an annual mortality rate of 18.7%. The risk of mortality did not differ significantly between the study and control groups with a hazard ratio of 1.020 (95% confidence interval = 0.724-1.437, p value = 0.912) after the adjustment for age and gender. Procedure-related complications occurred in 7.4% of the patients receiving PPM implants, and pocket hematoma was the most common one. The pre-implantation history of heart failure and cerebrovascular accident, rather than age, were significant predictors of mortality among PPM recipients. Conclusions Nonagenarians with severe bradyarrhythmias could retain the same life expectancies as those without bradyarrhythmias through PPM implantations. Extremely old age (> 90 years) should not be a barrier for PPM implants when indications were present.
    The Canadian journal of cardiology 01/2014; · 3.12 Impact Factor

Publication Stats

6k Citations
1,511.65 Total Impact Points

Institutions

  • 1996–2014
    • National Yang Ming University
      • • School of Medicine
      • • Institute of Clinical Medicine
      T’ai-pei, Taipei, Taiwan
  • 1992–2014
    • Taipei Veterans General Hospital
      • • Department of Medicine
      • • Cardiology Division
      T’ai-pei, Taipei, Taiwan
  • 2013
    • Tzu Chi University
      • Institute of Medical Sciences
      Hualian, Taiwan, Taiwan
  • 2011–2013
    • Buddhist Tzu Chi General Hospital
      T’ai-pei, Taipei, Taiwan
    • St. Mary's Hospital Luodong
      I-lan-hsien, Taiwan, Taiwan
    • Chi-Mei Medical Center
      臺南市, Taiwan, Taiwan
  • 2009–2013
    • Cathay General Hospital
      T’ai-pei, Taipei, Taiwan
    • Chiang Mai University
      • Department of Internal Medicine
      Chiang Mai, Chiang Mai Province, Thailand
  • 2003–2013
    • Mackay Memorial Hospital
      • Department of Internal Medicine
      T’ai-pei, Taipei, Taiwan
    • Taipei Medical University
      • • Division of Cardiology
      • • Graduate Institute of Clinical Medicine
      • • Division of Cardiovascular Medicine
      T’ai-pei, Taipei, Taiwan
  • 2002–2013
    • Wan Fang Hospital
      T’ai-pei, Taipei, Taiwan
  • 2012
    • Johns Hopkins Medicine
      Baltimore, Maryland, United States
  • 2011–2012
    • Cheng Hsin General Hospital
      T’ai-pei, Taipei, Taiwan
  • 2006–2011
    • University of the Ryukyus
      • Faculty of Medicine
      Okinawa, Okinawa-ken, Japan
  • 2003–2011
    • Chung Shan Medical University
      • Institute of Medicine
      臺中市, Taiwan, Taiwan
  • 2002–2011
    • National Defense Medical Center
      T’ai-pei, Taipei, Taiwan
  • 2010
    • Taipei City Hospital
      T’ai-pei, Taipei, Taiwan
    • Far Eastern Memorial Hospital
      T’ai-pei, Taipei, Taiwan
  • 2006–2009
    • Taichung Veterans General Hospital
      • Department of Internal Medicine
      Taichung, Taiwan, Taiwan
  • 2005–2008
    • Shin Kong Wu Ho-Su Memorial Hospital
      T’ai-pei, Taipei, Taiwan
    • Fu Jen Catholic University
      T’ai-pei, Taipei, Taiwan
    • University of Indonesia
      • Faculty of Medicine
      Depok, Daerah Istimewa Yogyakarta, Indonesia
  • 2007
    • Indiana University-Purdue University Indianapolis
      • Department of Medicine
      Indianapolis, IN, United States
  • 2004–2005
    • Kuang Tieng General Hospital
      T’ai-pei, Taipei, Taiwan
    • National Cerebral and Cardiovascular Center
      Ōsaka, Ōsaka, Japan
  • 1995
    • Singapore General Hospital
      • Department of Cardiology
      Tumasik, Singapore