Age-related effects on mortality of the implantable cardioverter defibrillator. An analysis of the Italian clinical service project database

Purpose: Chronic heart failure (CHF) is a common condition in elderly individuals. Despite great improvements in medical therapy, mortality is persistently high in the most severe forms of disease. Implantable cardioverter defibrillator (ICD) proved to significantly lengthen survival of very diseased CHF subjects. Epidemiological data show that sudden cardiac death has great relevance in aged patients, too. Aim of this study was to compare the age-related effects of ICD on mortality in a “real world” Italian population. Methods: According to the end-point of the study, all consecutive patients who underwent an ICD implantation in the 30 Italian centres participating to the “Clinical Service® Project” were divided into three age-groups (<65, 65-74 and ≥75 years). Clinical and instrumental variables were collected at baseline and during the follow-up. Results: Between March 2004 and May 2011, 6276 patients were enrolled in the project (LVEF: 29±9%). Subjects aged ≥75 years represented the 23.9% of the whole series (<65 - N=2455, age: 55±9; 65-74 - N=2318, age: 70±3; ≥75 - N=1503, age: 78±3). The proportion of men was >80% in all groups. The prevalence of all main comorbid conditions increased with age. CHF was most frequently due to coronary artery disease in elderly individuals, who also showed the worst NYHA class. The use of beta-blockers was inversely correlated with age (<65: 87.8%; 65-74: 79.8%; ≥75: 74.0%, p<0.001). At the end of the follow-up (median length: 31 months), all-cause mortality increased with age (<65: 7.0%; 65-74: 12.1%; ≥75: 15.2%; univariate Cox model - HR=1.65, p<0.0001). At multivariate analysis, age-group, NYHA Class, LVEF, chronic renal failure (all p values <0.001) and COPD (p=0.004) were significant predictors of prognosis. After adjustment, the age-group HR for mortality decreased to 1.57, a 16% reduction for the oldest patients explained by disease-related confounders. Conclusions: The analysis of the “Clinical Service® Project” database shows that ICD is useful also in elderly individuals with severely depressed systolic function. Overall mortality is associated not only with age, but with CHF severity and comorbidities, also. Pharmacological under-treatment still constitutes a relevant problem.