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Background: Atrial fibrillation (AF) is a leading preventable cause of heart failure (HF) for which early detection and treatment is critical. Subclinical-AF is likely to go untreated in the routine care of patients with cardiac resynchronization therapy defibrillator (CRT-D)., Hypothesis: The hypothesis of our study is that subclinical-AF is associated with HF hospitalization and increasing an inappropriate therapy., Methods: We investigated 153 patients with an ejection fraction less than 35%. We divided into three groups, subclinical-AF (n = 30), clinical-AF (n = 45) and no-AF (n = 78). We compared the baseline characteristics, HF hospitalization, and device therapy among three groups. The follow-up period was 50 months after classification of the groups., Results: The average age was 66 ± 15 years and the average ejection fraction was 26 ± 8%. Inappropriate therapy and biventricular pacing were significantly different between subclinical-AF and other groups (inappropriate therapy: subclinical-AF 13% vs clinical-AF 8.9% vs no-AF 7.7%: P = .04, biventricular pacing: subclinical-AF 81% vs clinical-AF 85% vs no-AF 94%, P = .001). Using Kaplan-Meier method, subclinical-AF group had a significantly higher HF hospitalization rate as compared with other groups. (subclinical-AF 70% vs clinical-AF 49% vs no-AF 38%, log-rank: P = .03). In multivariable analysis, subclinical-AF was a predictor of HF hospitalization., Conclusions: Subclinical-AF after CRT-D implantation was associated with a significantly increased risk of HF hospitalization. The loss of the biventricular pacing and increasing an inappropriate therapy might affect the risk of HF hospitalization., (© 2020 The Authors. Clinical Cardiology published by Wiley Periodicals LLC.)

Background: There are some controversial reports related to the pro-arrhythmic or anti-arrhythmic potential of cardiac resynchronization therapy (CRT) and little is known about the relationship between ventricular arrhythmia (VA) and left ventricular (LV)-lead threshold., Hypothesis: Upgrade CRT is anti-arrhythmic effect of VA with implantable cardioverter-defibrillator (ICD) patients and has a relationship with the incident of VA and LV-lead threshold., Methods: Among 384 patients with the implantation of CRT-defibrillator (CRT-D), 102 patients underwent an upgrade from ICD to CRT-D. We divided patients into three groups; anti-arrhythmic effect after upgrade (n = 22), pro-arrhythmic effect (n = 14), and unchanging-VA events (n = 66). The VA event was determined by device reports. We described the electrocardiography parameters, LV-lead characteristics, and clinical outcomes., Results: Before upgrade, the numbers of VA were 305 episodes and the numbers of ICD therapy were 157 episodes. While after upgrade, the numbers of VA were 193 episodes and the number of ICD therapy were 74 episodes. Ventricular tachycardia cycle length (VT-CL) after upgrade was significantly slower as compared to those with before upgrade. Pro-arrhythmic group was significantly higher with delta LV-lead threshold (after 1 month-baseline) as compared to those with anti-arrhythmic group (0.74 vs -0.21 V). Furthermore, pro-arrhythmic group was significantly bigger with delta VT-CL (after 3 months-before 3 months) as compared to those with anti-arrhythmic group (P = .03)., Conclusions: We described upgrade-CRT was associated with reduction of VA, ICD therapies and VT-CL. While 14 patients had a pro-arrhythmic effect and LV lead threshold might be associated with VA-incidents., (© 2019 The Authors. Clinical Cardiology published by Wiley Periodicals, Inc.)