Abstract 16873: Resting Heart Rate is Associated With Increased Risk for All-Cause Mortality Even After Considering Exercise Capacity: The Fit Project
OBJECTIVE: Resting heart rate (RHR) reflects parasympathetic nervous system activity and is inversely associated with mortality. Increased exercise capacity is also correlated with a decreased RHR and decreased risk of mortality. Whether RHR predicts mortality independent of exercise capacity is not well-established.
METHODS: We analyzed data from 54,420 adults without known CAD, CHF, or atrial fibrillation who underwent a clinically indicated exercise stress test at a single center between January 1991 and May 2009. Baseline RHR was divided into 5 groups with <60bpm as the reference. Exercise capacity was assessed by metabolic equivalents (METs) achieved during the stress test. Vital status was determined by the National Death Index through April 2013. Cox Proportional Hazard models were performed to determine the association of RHR with all-cause mortality after sequential adjustment for mortality risk factors and exercise capacity.
RESULTS: 63% were referred for evaluation of chest pain. Patients had a mean age of 52± 13 yrs, mean Framingham Risk Score of 11.5± 10%, mean RHR of 73± 12 bpm, and achieved a mean of 9.3±3 METs. RHR was inversely correlated with METs (r= -0.199). There were 5,700 deaths during mean follow-up of 11.1 years. Overall, compared to the lowest RHR group, patients with a RHR ≥90 bpm had a significantly increased risk for all-cause mortality even after adjustment for exercise capacity [HR 1.26, 95% CI 1.13-1.41 (model 2, TABLE)]. In sex stratified analyses, the relationship remained significant for men, but was no longer significant for women after adjustment for exercise capacity (p for interaction 0.002).
CONCLUSIONS: After adjustment for exercise capacity, increases in RHR were an independent risk factor for all-cause mortality in men but not women. Future studies are needed to determine whether lifestyle and pharmaceutical regimens specifically targeted to reduce RHR are beneficial for people with moderate to high levels of RHR.
- © 2013 by American Heart Association, Inc.