Background: Abnormal non-ST segment treadmill parameters are associated with an increased mortality risk. Such measures include fitness, resting heart rate (HR), chronotropic incompetence, and HR recovery. However, whether there is an additive association among these parameters and the risk of mortality is unknown.
Design: Prospective observational registry study.
Methods: We assessed the risk of cardiovascular and all-cause mortality in 25 642 individuals as an additive function of the number of these parameters. Abnormal responses were defined as follows: abnormal resting HR as a HR>or=80 bpm, abnormal fitness as an adjusted fitness level in the lowest 20%, chronotropic incompetence as an inability to achieve at least 80% of the predicted HR reserve, and abnormal HR recovery as an HR decline less than 12 bpm 1 min after exercise.
Results: During 7.2 years of follow-up, 392 participants died, with 94 from cardiovascular causes. Each parameter was significantly associated with all-cause and cardiovascular mortality (P<0.01) after adjustment for cardiovascular risk factors. There was a significant trend between both all-cause or cardiovascular mortality and the number of abnormal parameters (P<0.05).
Conclusion: There is a continuum of risk as the number of abnormal parameters increases, suggesting that it may be important to determine their presence and number during exercise testing.