Key result
Primary prevention ICDs show no significant all-cause mortality benefit in an underserved cohort.
Why the study?
Prior registry studies showed underutilization of primary prevention ICD therapy, and advances in heart failure therapies have prompted debate over two-decade-old guideline criteria, particularly in NICM and elderly subgroups. Contemporary referral determinants, decision-making processes, and outcomes of primary prevention ICD therapy needed characterization in a diverse, under-represented population.
Does primary prevention ICD implantation reduce all-cause mortality in a contemporary diverse, underserved population meeting Class I criteria?
Cohort (n=559)
No
Does primary prevention ICD implantation reduce all-cause mortality in a contemporary diverse, underserved population meeting Class I criteria?
In a contemporary underserved cohort, nearly 40% of eligible patients were never referred for primary prevention ICD (particularly women, those with high social vulnerability, and those managed by generalists), and overall ICD implantation was not significantly associated with reduced all-cause mortality.
Answers are grounded in this paper and cite their sources.
Should not yet change practice in underserved cohorts; leaves open etiology-specific effects for prospective trials.
BACKGROUND: Registry studies from 2000-2010 demonstrated underutilization of primary prevention ICD therapy. As heart failure therapies have reduced sudden cardiac death, investigators have questioned guidelines derived from trials conducted two decades prior, particularly in non-ischemic cardiomyopathy (NICM) and elderly subgroups. We characterized contemporary referral determinants, decision-making processes, and outcomes of primary prevention ICD therapy in a diverse, under-represented population. METHODS: In this retrospective single-center cohort study, we reviewed records of all patients meeting Class I criteria for primary prevention ICD in 2019. Multivariable logistic regression identified factors associated with ICD referral, and time-varying Cox models compared all-cause mortality by implantation status through 2022. RESULTS: Of 559 eligible patients, 345 (62%) were referred and 227 (41%) underwent implantation. Referral was associated with male gender, care coordination by a cardiologist rather than a generalist, and lower social vulnerability index (SVI) score. No decision-making rationale was documented for a plurality of non-referred and non-implanted patients; documented rationales identified potential intervention targets. ICD implantation was not associated with all-cause mortality (aHR 0.74, 95% CI 0.49-1.12). In exploratory analyses stratified by cardiomyopathy type, implantation was associated with lower mortality in ischemic cardiomyopathy (aHR 0.51, 95% CI 0.27-0.95) but not in NICM (aHR 1.11, 95% CI 0.63-1.95). CONCLUSION: Many eligible patients are never referred for ICD therapy. Female gender, generalist care coordination, and high SVI were associated with non-referral. The exploratory association of implantation with lower mortality in ischemic cardiomyopathy was not significant in propensity score overlap-weighted analyses. The NICM estimate was imprecise.
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Song et al. (2026) conducted a cohort in Cardiomyopathy/heart failure meeting Class I criteria for primary prevention ICD (n=559). Primary prevention ICD implantation vs. No ICD implantation was evaluated on All-cause mortality (aHR 0.74, 95% CI 0.49-1.12). Primary prevention ICD implantation was not significantly associated with lower all-cause mortality (aHR 0.74, 95% CI 0.49-1.12) in an underserved cohort.