Acquired ventricular septal defects (VSD) are rare and devastating complications after myocardial infarction. The long-term prognosis with medical therapy is extremely poor. We report on a patient who developed progressive heart failure within 3 months after myocardial infarction due to an unknown VSD. The left ventricular function was severely impaired. After diagnosing VSD by echocardiography, surgical occlusion was performed. In addition, a biventricular pacemaker was applied using epicardial leads. The patient recovered almost completely 6 weeks postoperative. Beside hemodynamic changes, biventricular pacing is potentially sufficient to improve the postoperative outcome of patients with severe heart failure in these conditions.