Background: We sought to determine whether treadmill exercise time may be of value as an initial prognostic screening tool in ambulatory patients with impaired systolic function who are referred for cardiopulmonary exercise testing.
Methods and results: We studied 2231 adult systolic heart failure patients (27% of whom were women) who underwent cardiopulmonary stress testing using a modified Naughton protocol. We assessed the value of treadmill exercise time for prediction of all-cause death and a composite of death or United Network for Organ Sharing status 1 heart transplantation. During a mean follow-up of 5 years, 742 patients (33%) died. There were 249 United Network for Organ Sharing status 1 heart transplants (11%). Treadmill exercise time was predictive of death and the composite outcome in both women and men, even after accounting for peak oxygen consumption and other clinical covariates (adjusted hazard ratio of lowest versus high sex-specific quartile for prediction of death 1.70, 95% confidence interval 1.05 to 2.75, P=0.03; for prediction of the composite outcome, 1.75, 95% confidence interval 1.15 to 2.66, P=0.009). For a 1-minute change in exercise time, there was a 7% increased hazard of death (eg, comparing 480 to 540 seconds, hazard ratio =1.07, 95% confidence interval 1.02 to 1.12, P=0.004).
Conclusions: Because cardiopulmonary stress testing is not available in every hospital, treadmill exercise time with a modified Naughton protocol may be of value as an initial prognostic screening tool.