Does cigarette smoking paradoxically increase survival in idiopathic dilated cardiomyopathy? The Washington, DC, dilated cardiomyopathy study

Recent studies have suggested that patients with idiopathic dilated cardiomyopathy (IDCM) who smoke have an improved prognosis as compared with nonsmokers. We examined this paradoxical finding using data from a population-based study in Washington, D.C. (n = 127). Current smokers were more likely to have a left-ventricular ejection fraction (LVEF) of 25% or greater as compared with IDCM patients who were past smokers or lifelong nonsmokers (p less than or equal to 0.02). The cumulative survival among current smokers at 12 and 24 months was 88.1 and 81.4%, respectively, as compared with 77.9 and 71.6% among past smokers and 74.0 and 64.3% among patients who had never smoked. In a univariate analysis using the proportional hazards model, lifelong nonsmokers and former smokers were about twice as likely to die as compared with smokers, although the association was not significant (p > 0.10). In multivariable analysis, older age, LVEF, and ventricular arrhythmias - but not cigarette smoking - were found to be statistically significant independent predictors of survival (p less than or equal to 0.05).