Abstract 3192: An Increasing Number of Abnormal Exercise Parameters Is Associated with Increasing All-Cause and Cardiovascular Mortality
Background: Abnormal exercise parameters during treadmill testing are associated with an increased mortality risk. Such non-ST segment measures include resting heart rate (HR), cardiorespiratory fitness, proportion of HR reserve used, and HR recovery. Each has been shown individually to add prognostic value independent of traditional risk factors. However, whether those with a greater number of these parameters are at higher risk than those with fewer abnormalities is unknown.
Methods: We assessed cardiovascular and all-cause mortality as a function of the number of these abnormal exercise parameters. The study population consisted of 25,250 men and women free of any known cardiovascular disease at baseline. An abnormal resting HR was defined as a resting HR > 65 bpm. An abnormal cardiorespiratory fitness status consisted of those with an age- and gender-adjusted fitness level in the lowest 20%. An abnormal HR reserve was defined as an inability to achieve at least 80% of the predicted HR reserve. An abnormal HR recovery was defined as a HR decline < 12 bpm at 1 minute after peak exercise.
Results: During a median follow-up of 7.2 years, 392 participants died, with 94 from cardiovascular causes. Each of the examined exercise parameters were significantly associated with all-cause mortality (p<0.05), while all but an abnormal resting HR were significantly associated with cardiovascular mortality (p<0.05). These relations remained intact after adjustment for age and other traditional cardiovascular risk factors. There was a significant trend noted between both all-cause or cardiovascular mortality and the number of abnormal exercise parameters (p<0.05 for trend). This risk increased incrementally and peaked in those with 3– 4 abnormal exercise parameters (hazard ratio for all-cause mortality 5.7, 95% CI 3.6 – 8.8; hazard ratio for cardiovascular mortality 5.4, 95% CI 2.5–11.5).
Conclusions: There is a continuum of risk as the number of abnormal exercise parameters increases. These findings indicate that it is important to determine the presence and number of these abnormal parameters during exercise testing.