Keywords:Exercise test heart failure cardiovascular disease implantable defibrillator sudden death ventricular arrhythmia VO2 A B S T R A C T Malignant ventricular arrhythmia (MVA) is one of the most frequent causes of mortality among patients with cardiovascular disease. Exercise tolerance is a powerful variable to evaluate the cardiopulmonary system condition. The proposal of this research is to establish an association between peak oxygen uptake (VO2) and the incidence of long-term malignant ventricular arrhythmia. Methods:A historical cohort of patients with heart disease of a third level hospital of cardiology were studied. Every patient performed a symptoms-limited cardiopulmonary exercise testing and were followedup to10 years. We defined malignant ventricular arrhythmia (MVA) as a combined outcome composed by tachycardia or ventricular fibrillation, implantation of a cardioverter (ICD) or sudden death. Patients were split in 2 groups according to MVA. Using a ROC curve, peak VO2 was divided in two groups, according to a 25 mlO2/kg/min cut-point. Bivariate analysis identified those variables associated with MVA, that were included in a multivariable regression Cox model. All p values less than 0.05 were considered stochastically significant.Results: A total of 1767 individuals were studied, and 116 combined outcomes occurred. After Cox regression analysis, four variables were identified as statistically significant risk-factors for MVA: reduced VO2 (HR 1.75, CI 95% 1.04 to 2.92), heart failure (HR 6.15, CI 95% 2.85 to 13.21), history of ICD (HR 2.12, CI 95% 1.26 to 3.55) and diuretic use (HR 2.6, CI 95% 1.6 to 4.2). Conclusion:Maximal exercise tolerance is strongly associated with a long-term occurrence of malignant ventricular arrhythmia, together with other variables such as heart failure, history of previous ICD or diuretic use.