Maximal exercise oxygen pulse as a predictor of mortality among male veterans referred for exercise testing

Background Maximal oxygen pulse (02 pulse) mirrors the stroke volume response to exercise, and should therefore be a strong predictor of mortality. Limited and conflicting data are, however, available on this issue. Methods Nine hundred forty-eight participants, classified as those with cardiopulmonary disease (CPD) and those without (non-CPD), underwent cardiopulmonary exercise testing (CPX) for clinical reasons between 1993 and 2003. The ability of maximal O-2 pulse and maximal oxygen uptake (peak VO2) to predict mortality was investigated using proportional hazards and Akaike information criterion analyses. All-cause mortality was the endpoint. Results Over a mean follow-up of 6.3 +/- 3.2 years, there were 126 deaths. Maximal 02 pulse, expressed in either absolute or relative to age-predicted terms, and peak VO2 were significant and independent predictors of mortality in those with and without CPD (P<0.04). Akaike information criterion analysis revealed that the model including both maximal O-2 pulse and peak VO2 had the highest accuracy for predicting mortality. The optimal cut-points for O-2 pulse and peak VO2 (<12; >= 12 ml/beat and <16; >= 16 ml/(kg (.) min) respectively) were established by the area under the receiver-operating-characteristic curve. The relative risks of mortality were 3.4 and 2.2 (CPD and non-CPD, respectively) among participants with both maximal O-2 pulse and peak VO2 responses below these cut-points compared with participants with both responses above these cut-points. Conclusion These results indicate that maximal O-2 pulse is a significant predictor of mortality in patients with and without CPD. The addition of absolute and relative O-2 pulse data provides complementary information for risk-stratifying heterogeneous participants referred for CPX and should be routinely included in the CPX report. Eur J Cardiovasc Prev Rehabil 16:358-364 (C) 2009 The European Society of Cardiology