The incidence of secondary ventricular fibrillation (VF) complicating acute myocardial infarction (AMI) was 2.4% in a large cohort of unselected patients with AMI (142 of 5,839). Secondary VF was more frequent in patients with recurrent AMI (4%) than in those with a first AMI (1.9%) (p < 0.01). The hospital course was more complicated and in-hospital mortality was significantly higher in patients with secondary VF than in those with the same clinical hemodynamic condition but without VF (56 vs 16%; p < 0.0001). Multivariate analyses confirmed secondary VF complicating AMI as an independent predictor of high in-hospital mortality, with an odds ratio of 7 (95% confidence interval 4.6-10.6). However, long-term mortality after discharge (mean follow-up 5.5 years) was not increased in patients with as compared with those without secondary VF (39 vs 42%). These findings were also true when patients receiving beta blockers and antiarrhythmic therapy were excluded from analysis. Thus, this life-threatening arrhythmia occurring during hospitalization is not a marker of recurrent susceptibility to VF or an indicator of increased mortality after discharge from the hospital.