Implantable cardioverter-defibrillators in cardiac transplant recipients: A systematic review from the Electrophysiology Collaborative Consortium for Meta-analysis-ELECTRAM investigators.

Introduction: Implantable cardioverter-defibrillator (ICD) in patients with heart failure with reduced ejection fraction reduces mortality secondary to malignant arrhythmias. Whether cardiac transplant patients considered high risk for sudden death (SD) derive similar benefits remains controversial.
Methods: Systematic search, without language restriction, using PubMed, EMBASE, SCOPUS, Google Scholar, and ClinicalTrials.gov was performed from inception to June 4, 2020, for studies that had reported outcomes in patients who had ICD implanted after cardiac transplant. The outcomes studied were as follows: (a) SD and (b) appropriate and inappropriate ICD therapies.
Results: Seven studies (from 1983 through 2018) with a total of 338 cardiac transplant patients who received ICD met study inclusion criteria. The mean age was 48.37 ± 14.85 years, and 70.4% were men. The pooled incidence of SD was 16.3% (95% CI 6.2-29.0%; I ²   = 66%). Appropriate and inappropriate ICD therapies were observed in 12.1% (95% CI 5.3-20.4; I ²   = 0%) and 3.5% (95% CI 0.11-9.58%; I ²   = 0%), respectively during the follow-up period (27.48 ± 24.27 months). The most common cause for SD was heart failure (15.6%), followed by electromechanical disassociation, malignant ventricular arrhythmias (4.7% each, respectively), and cardiac allograft vasculopathy (CAV) (3.1%). Furthermore, approximately 60% (10/17) of patients with appropriate ICD shocks had CAV.
Conclusion: Despite, low incidence of arrhythmic mortality, there remains an increased burden of ventricular arrhythmias, as evident by a 12% appropriate ICD shock rates, suggesting ICD might be a practical decision in selected cardiac transplant patients deemed high risk of SD (i.e., patients with advanced CAV and left ventricular systolic dysfunction).
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