Differences in predictors of implantable cardioverter-defibrillator therapies in patients with ischaemic and non-ischaemic cardiomyopathies

AIMS: Implantable cardioverter-defibrillators (ICDs) have been shown to reduce mortality in patients with both ischaemic and non-ischaemic cardiomyopathy by terminating life-threatening arrhythmias. However, such arrhythmic events are unequally distributed among different patient subgroups. We aimed to evaluate predictors of appropriate ICD therapies as a step towards risk stratification in a real-world cohort. METHODS AND RESULTS: The prevalence and predictors of appropriate ICD therapies were analysed in 330 consecutive patients (mean age 65 ± 11, 81% male) with implanted ICDs due to ischaemic (n = 204) or dilated (n = 126) cardiomyopathy. During a mean follow-up of 19 ± 9 months, 1545 appropriate ICD therapies (antitachycardia pacing and shocks) were detected in 94 patients (29%). In multivariate analysis applied on the whole cohort, the presence of atrial fibrillation [AF: odds ratio (OR) = 1.906, confidence interval (CI) = 1.143-3.177, P = 0.013] and secondary prevention indication (OR = 1.963, CI = 1.123-3.432, P = 0.018) was associated with ICD therapy. The presence of cardiac resynchronization therapy (CRT) had a protective value (OR = 0.563, CI = 0.327-0.968, P = 0.038). Moreover, the predictors were different depending on the aetiology of the cardiomyopathy: in the ischaemic group, only secondary prevention indication (OR = 2.0, CI = 1.029-3.891, P = 0.041) and the presence of a biventricular system (OR = 0.359, CI = 0.163-0.794, P = 0.011) remained significant, while in the non-ischaemic group, an association with AF was observed (OR = 4.281, CI = 1.632-11.231, P = 0.003). CONCLUSION: The aetiology of cardiomyopathy should be taken into consideration for the therapy of ICD patients. The protective role of CRT devices should be pointed out in ischaemic cardiomyopathy (ICM) and a more rigorous antiarrhythmic treatment should be considered for ICM patients with secondary prevention or for dilated cardiomyopathy patients with AF.