Abnormal delay in recovery of pulse rate in 9454 patients referred for treadmill exercise test to Cleveland Clinic, 1990-1997--an independent predictor of excess mortality.

ABSTRACT

OBJECTIVE: The objective of this article is to present results from the latest of 3 recent reports from the Cleveland Clinic on excess mortality associated with abnormal delay in the recovery of an elevated pulse rate produced in a treadmill exercise test. This is done in the context of a long-standing medical interest in this phenomenon and its prognostic significance (see Comment section). BACKGROUND: Delay in return of the pulse rate after exercise has long attracted medical interest as a potentially unfavorable prognostic factor. However, this has not become a factor in the interpretation of the treadmill exercise test. Cardiologist staff members of the Cleveland Clinic have recently studied the mortality predictive effect of delay in pulse recovery in 3 different cohorts of patients given a treadmill exercise test (modified Bruce protocol). The newest, largest and most complete of these studies is the source article for this report. STUDY DESIGN: This was an observational follow-up (FU) study with a median of 5.2 years (range 1.4-8.7 years). The patients were categorized as abnormal pulse recovery at 1 minute after peak exercise with decrease of only 12 beats per minute or less, and normal if >12 beats per minute. These classes were combined with dichotomous classes according to the exercise test result and with other associated risk factors. RESULTS: A good approximation of exposure was achieved for each of the 4 pulse recovery/exercise test groups. From numerical data in the article, it was possible to derive aggregate mean annual mortality rates for these groups and selected combinations of pulse recovery with other risk factors. Mortality was lowest (2.8 per 1000) in the group with pulse recovery and exercise test both normal (66% of the total patients screened), and this was used as the "expected" rate, without adjustment for any differences in age. On this basis the excess death rate (EDR) was about 7 per 1000 per year when either pulse recovery or exercise test was abnormal, and 28 per 1000 when both were abnormal. Similar levels of EDR were found in the combinations of pulse recovery with other risk factors. CONCLUSION: Abnormal pulse recovery after the treadmill exercise test is a powerful and independent predictor of significant excess mortality.