Etiology-dependent prognostic impact of atrial fibrillation in implantable cardioverter-defibrillator and cardiac resynchronization therapy recipients.

BACKGROUND

Atrial fibrillation (AF) is a common comorbidity in patients receiving implantable cardioverter-defibrillators (ICD) or cardiac resynchronization therapy (CRT) and is associated with increased mortality. However, most evidence comes from Western cohorts dominated by ischemic cardiomyopathy (ICM), limiting applicability to populations in which non-ICM (NICM) is more prevalent. Because NICM and ICM fundamentally differ in myocardial pathology and remodeling, the prognostic impact of AF may not be uniform across etiologies.

OBJECTIVE

This study aimed to determine whether the prognostic impact of AF differs between NICM and ICM in ICD/CRT patients.

METHODS

We analyzed data from 4,623 patients in a nationwide cardiac device registry. Outcomes were all-cause death, cardiac death, heart failure hospitalization, and ICD therapies. Multivariable Cox and Fine-Gray competing risk models were constructed using literature-based, MAGGIC-derived, and stepwise covariate selection strategies. Propensity score matching was performed within ICM and NICM subgroups.

RESULTS

AF was associated with higher risks of mortality, cardiac death, and heart failure hospitalization in NICM across all models. In contrast, the association between AF and mortality in ICM was attenuated and no longer statistically significant after multivariable adjustment. After propensity score matching, AF remained associated with increased mortality in NICM but not in ICM. AF impact on rates of ICD therapies did not differ between etiologies.

CONCLUSION

The prognostic impact of AF among ICD/CRT recipients differs markedly by cardiomyopathy etiology. AF identifies a high-risk subgroup within NICM, whereas its effect is attenuated in ICM. Etiology-specific risk assessment should be incorporated into clinical management.