BACKGROUND: Although primary preventive therapy with implantable cardioverter defibrillators has recently been shown to be effective in patients with coronary artery disease and left ventricular dysfunction, further identification of patients at particularly high risk for arrhythmic death would improve the cost effectiveness of device therapy. The value of risk stratification in postinfarction patients with versus those without left ventricular dysfunction has not been investigated in detail in infarct survivors treated according to contemporary therapeutic guidelines. METHODS: Patients with acute myocardial infarction underwent coronary angiography including left ventricular angiography in an attempt to restore antegrade flow of the infarct-related artery. Additionally, patients underwent noninvasive autonomic risk stratification by means of heart rate variability (HRV) and baroreflex sensitivity (BRS) measurements prior to hospital discharge. RESULTS: A total of 411 patients were prospectively included in the study. The primary study endpoint of cardiac death and arrhythmic events was significantly more common in patients with LVEF < or = 35% as compared to those with preserved LV function (27% vs 4%; P < 0.0001). In patients with LV dysfunction, HRV and BRS were significant risk predictors on univariate (P < 0.01 for BRS; P = 0.04 for HRV) and multivariate (P = 0.028 for BRS; P = 0.053 for HRV) analyses. In contrast, in patients with preserved LV function, only patency of the infarct artery but not autonomic markers was significantly predictive of cardiac death and arrhythmic events. CONCLUSION: The present study demonstrates that autonomic testing does not yield predictive power in infarct survivors with preserved left ventricular function. Accordingly, cost effectiveness of risk stratification and subsequent preventive therapy may be improved by restricting risk stratification to patients with impaired LV function.