Assessment of the prognostic utility of the FIT treadmill score in coronary artery disease patients undergoing cardiac rehabilitation

Introduction: Cardiovascular fitness is an important goal in cardiac rehabilitation (CR) programs and is predictive of outcomes. We sought to determine the utility of a novel clinical treadmill score in determining prognosis of coronary artery disease (CAD) patients after CR. Methods: Demographic, clinical and exercise data of 262 patients (mean age 55.8 ± 10.1 years) who completed an outpatient CR program were analyzed. The FIT treadmill score was determined prior to program initiation and after completion. Patients were classified according to risk category using the FIT scores after CR completion and were followed up for the occurrence of 10 year all cause mortality. Results: On median follow up of 10.3 years, 52 patients died. An improvement of the FIT treadmill score by 18.2 points was associated with a 21% reduction in mortality (multivariate-adjusted Hazard Ratio 0.79, 95% CI 0.56-1.08, P ≤ 0.05). Kaplan-Meier survival curves showed increased occurrence of mortality in the high-risk group. After adjustment for confounders a high-risk FIT score category on exit (HR: 2.7, 95% CI 1.41-5.17, P ≤ 0.05) was predictive of increased mortality. Both an improvement in the FIT score (AUC=0.81) and the FIT score category on exit (AUC=0.92) had good discrimination in predicting mortality. Conclusion: The FIT treadmill score is predictive of all cause mortality in patients with CAD undergoing CR. An improvement in the FIT score after CR is associated with improved survival. The FIT score may be a useful prognostic marker of overall cardiovascular fitness and successful outcome for patients who participate in CR programs.