Estimated age based on exercise stress testing performance may be a better predictor of mortality than chronological age, according to a study published online Feb. 13 in the European Journal of Preventive Cardiology.
Serge C. Harb, M.D., from the Cleveland Clinic, and colleagues evaluated whether age based on stress testing exercise performance (A-BEST) would be a better predictor of mortality than chronological age among 126,356 consecutive patients (mean age, 53.5 years) referred for exercise (electrocardiography, echocardiography, or myocardial perfusion imaging) stress testing between Jan. 1, 1991, and Feb. 27, 2015. Exercise capacity (number of peak estimated metabolic equivalents of task), chronotropic reserve index, and heart rate recovery were used to compute estimated age taking into account patient’s gender and medications that affect heart rate.
The researchers found that after adjustment for clinical comorbidities, improved survival was associated with higher metabolic equivalents of task (adjusted hazard ratio [aHR] for mortality, 0.71) and higher chronotropic reserve index (aHR for mortality, 0.97). Higher mortality was associated with abnormal heart rate recovery (aHR for mortality, 1.53) and higher A-BEST (aHR for mortality, 1.05). There was a significant increase in the area under the curve when A-BEST rather than chronological age was used in prediction models (0.82 versus 0.79). The overall net reclassification improvement was significant.
“For the first time we can quantify the impact of your performance level on a treadmill test in adding or subtracting years from your actual age,” Harb said in a statement.