Benefit of implantable cardioverter defibrillator use in Japanese patients based on modified MADIT-ICD benefit score

Aims: The MADIT-ICD benefit score is used to stratify the risk of life-threatening arrhythmia and non-arrhythmic mortality. We sought to develop an implantable cardioverter defibrillator (ICD) benefit-prediction score for Japanese patients with ICDs.

Methods: Patients who underwent ICD implantation as primary prophylaxis were retrospectively enrolled. Based on their MADIT-ICD benefit scores, we developed a modified MADIT-ICD benefit score adapted to the Japanese population. The primary endpoints were appropriate ICD therapy and all-cause death without appropriate ICD therapy (non-arrhythmic death). We used the Fine and Gray multivariate model and Cox proportional hazard regression to identify factors for adjusting the MADIT-ICD benefit-risk score specifically for the Japanese population. The scoring points for the original MADIT-ICD benefit score were adjusted to optimal points based on the multivariate analysis results in the population.

Results: The study enrolled 167 patients [age, 61.9 ± 12.3 years; male individuals, 138 (82.6%); cardiac resynchronization therapy, 73 (43.7%); ischaemic cardiomyopathy, 53 (31.7%)]. Fourteen patients received anti-tachycardia pacing (ATP) therapy, and 23 received shock therapy as the initial appropriate ICD therapy. Non-arrhythmic deaths occurred in 37 patients. The original MADIT-ICD benefit score could not stratify non-arrhythmic mortality in the Japanese population. The patients were reclassified into three groups according to the modified MADIT-ICD benefit score. The modified MADIT-ICD benefit score could effectively stratify the incidence of appropriate ICD therapy and non-arrhythmic mortality. In the highest-benefit group, the 10 year cumulative rates of appropriate ICD therapy and non-arrhythmic mortality were 56.8% and 12.9%, respectively (P < 0.01). In the intermediate-benefit group, these rates were 20.2% and 40.2% (P = 0.01). In the lowest-benefit group, the incidence of non-arrhythmic deaths was 68.1%, and no patient received appropriate ICD therapy.

Conclusions: The modified MADIT-ICD benefit score may be useful for stratifying ICD candidates in the Japanese population.