Cardiac Resynchronization Therapy May Be Antiarrhythmic Particularly in Responders: A Systematic Review and Meta-Analysis

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OBJECTIVES: This study sought to study the effect of echocardiographic response to cardiac resynchronization therapy (CRT) on ventricular arrhythmias (VA). The effect of CRT-defibrillator on sustained VA was compared with implantable cardioverter-defibrillator (ICD)-only therapy. BACKGROUND: CRT is an effective adjunctive therapy in selected patients with advanced congestive heart failure, but its effect on VA remains controversial. METHODS: PubMed was searched to identify studies. For primary comparison, studies reporting incidence of VA in patients with congestive heart failure with CRT compared with ICD were included. For secondary comparison, studies reporting incidence of VA in echocardiographic responders compared with nonresponders were included. Studies reporting incidence of VA in CRT nonresponders before and after CRT upgrade from ICD were assessed for the third comparison. Inverse variance method in a random-effects model was used to combine effect sizes. RESULTS: Thirteen studies (4,631 subjects) were included in the primary meta-analysis. Patients with CRT had a significantly lower incidence of VA compared with patients with ICD only (odds ratio: 0.754; confidence interval: 0.594 to 0.959). Thirteen studies (n = 3,667) were included in the meta-analysis of VA in CRT responders versus nonresponders. Responders had a significantly lower risk of VA (odds ratio: 0.436; confidence interval: 0.323 to 0.589). Multivariate meta-regression showed that the percentage beta-blocker use and follow-up duration explained heterogeneity between the studies. Three studies were included in the comparison of VA in CRT nonresponders before and after upgrade from ICD. CRT nonresponders had an elevated risk of VA compared with ICD-only subjects (odds ratio: 1.497; confidence interval: 1.225 to 1.829). CONCLUSIONS: CRT may significantly reduce risk of VA compared with ICDs in patients who meet criteria for CRT. CRT responders have significant reduction in VA compared with nonresponders. CRT nonresponse might significantly increase risk of VA.

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JACC. Clinical electrophysiology

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