Patients at risk for cardiac death late after aortic valve replacement. A total of 100 patients aged 24 to 78 years were screened prospectively a mean of 71 months after aortic valve replacement for the presence of left ventricular hypertrophy (LVH) on the ECG (Estes scores greater than or equal to 5.0) and for repetitive ventricular premature beats VPBs greater than or equal to 2 couplets/24 hr) during 24-hour Holter monitoring. During the subsequent 41-month follow-up (range 10 to 50 months), the yearly cardiac mortality rate was 1.3% in patients with LVH, 2.9% in patients with VPBs, and 8.0% in patients with LVH plus VPBs but only 0.6% when none of these factors was present (p less than 0.05 chi 2 test). The patient groups did not differ with regard to age, time elapsed since operation, underlying valve lesion, and coronary artery disease. Both LVH and VPBs occurred more frequently in patients with left ventricular dysfunction. We conclude that after aortic valve replacement cardiac mortality is markedly increased in patients with LVH and repetitive VPBs, since they are noninvasive markers of left ventricular dysfunction. 