Importance
Current guidelines do not recommend primary prevention implantable cardioverter-defibrillators (ICDs) unless a patient's left ventricular ejection fraction (LVEF) is 35% or less. Many sudden cardiac deaths (SCD) occur when LVEF is 36% to 50%. Myocardial scar (a key arrhythmic substrate) can be assessed by late gadolinium enhancement on cardiovascular magnetic resonance (CMR), but robust evidence is lacking regarding a scar-based approach to ICD insertion.
Objective
To determine whether implantation of ICDs reduces SCD or hemodynamically significant ventricular arrhythmia (HSVA) in patients with an LVEF of 36% to 50% and myocardial scar.
Design, Setting, and Participants
An open-label randomized clinical trial enrolled adults between 2015 and 2022 who had ischemic or nonischemic cardiomyopathy, an LVEF of 36% to 50%, CMR-defined myocardial scar, and were receiving guideline-directed medical therapy at 18 sites in Australia, Germany, and the UK. Follow-up assessments were completed in 2026.
Interventions
A primary prevention ICD (n = 180) vs an implantable loop recorder (ILR) (n = 173).
Main Outcomes and Measures
The primary composite outcome was SCD or HSVA. Five secondary outcomes were evaluated: SCD, HSVA, heart failure-related hospitalization, cardiovascular mortality, and all-cause mortality.
Results
Of 353 patients randomized (median age, 65 years [IQR, 57-61 years]; 18% female; and 72% had an ischemic etiology), 70% had an LVEF of 40% or greater. The median follow-up was 6.3 years (IQR, 4.8-7.6 years). The primary composite outcome occurred in 14 patients (7.8%) in the ICD group compared with 16 patients (9.2%) in the ILR group (hazard ratio [HR], 0.76 [95% CI, 0.37-1.58]). For the individual components of the primary composite outcome, SCD occurred in 3 patients (1.7%) vs 10 patients (5.8%) in the ILR group (HR, 0.26 [95% CI, 0.07-0.95]) and HSVA occurred in 12 patients (6.7%) vs 6 patients (3.5%), respectively (HR, 1.77 [95% CI, 0.65-4.81]). The rates for all-cause mortality, cardiovascular mortality, and heart failure-related hospitalization were similar between groups. In a prespecified analysis of 6 subgroups, the primary outcome occurred less often in patients younger than 70 years in the ICD group (3.3%) vs patients in the ILR group (10.0%) (HR, 0.28 [95% CI, 0.09-0.89]) but not in those aged 70 years or older (16.9% vs 7.5%, respectively) (HR, 2.33 [95% CI, 0.75-7.26]; P = .01 for interaction).
Conclusions and Relevance
Implantation of an ICD did not reduce the composite outcome of SCD or HSVA in patients with an LVEF of 36% to 50% and myocardial scar.
Trial Registration
ClinicalTrials.gov Identifier: NCT01918215.
J. Selvanayagam, John G. F. Cleland, G. Hillis et al.· Journal of the American Medi...· 0 citations
Abstract Introduction Cardiovascular disease is a leading cause of death worldwide, of which coronary artery disease is the most common form. Sudden cardiac death (SCD) is a serious complication following acute myocardial infarction (MI), accounting for the highest percentage of all deaths in this population. Currently implantable cardioverter-defibrillators (ICDs) provide an acceptable method of primary prevention of SCD. However, the current literature is heterogeneous with regard to studies evaluating the benefits of ICDs for the primary prevention of SCD after MI, particularly relating to the timing of ICD implantation, risk stratification of patients for ICD implant selection and reporting non-rhythmic deaths after ICD implantation. Methods and analysis A meta-analysis will be performed to estimate the pooled effect size of randomised controlled trials (RCTs) examining the relationship between prophylactic transvenous ICD (TV-ICD) implantation and other medical therapies for primary prevention of SCD after MI. A comprehensive literature search and review will be performed using electronic medical databases including Scopus, Ovid MEDLINE, EMBASE (Ovid Platform), Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, ProQuest (Health and Medicine) and CINAHL (EBSCO) from January 1980 to June 2025. The literature search will be limited to peer-reviewed original studies carried out in human subjects and published in English. Type of study design will be limited to RCTs. The systematic review and meta-analysis will be developed according to the Joanna Briggs Institute Manual for Evidence Synthesis (2024 edition) and conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis 2020 guidelines. Data analysis will be performed according to a structured and predetermined analysis plan. The primary outcome of the study will be all-cause-mortality, for which Hazard Ratios (HRs) will be reported as a measure of effect with 95% CI. Based on data availability, subgroup analysis will be carried out. The effect sizes will be reported based on a random effects model. Expected study outcomes and dissemination This systematic review and meta-analysis will evaluate and provide primary evidence for the effectiveness of prophylactic implantation of TV-ICDs on all-cause mortality in patients who experienced MI, aiming for primary prevention of SCD after MI. The primary prevention of SCD after MI is an important goal to reduce community incidence of out-of-hospital cardiac arrests, improving patient survival rates and their quality of life after MI. Out-of-hospital cardiac arrests currently have a survival rate of less than 10% and could result in long-lasting neurological damage in those who survive. PROSPERO registration CRD42023456995.
A. Amarasekera, Anoja W. Gunaratne, J. Kovoor et al.· BMJ Open· 0 citations
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