TUESDAY, Nov. 22, 2016 (HealthDay News) -- The prognostic value of lower heart rate thresholds (defined as the percentage of age-predicted maximal heart rate achieved, or ppMHR) is attenuated for patients on beta-blocker therapy (BBT), according to a study published in the Dec. 1 issue of The American Journal of Cardiology.
Rupert K. Hung, M.D., from the Johns Hopkins Ciccarone Center for the Prevention of Heart Disease in Baltimore, and colleagues conducted a retrospective cohort study involving 64,549 adults without congestive heart failure or atrial fibrillation who underwent clinician-referred exercise stress testing, with median follow-up of 10.6 years. The authors examined the effect of BBT, ppMHR, and estimated exercise capacity on mortality.
The researchers identified 9,259 deaths during follow-up. BBT correlated with an 8 percent lower adjusted achieved ppMHR (91 versus 83 percent for no BBT versus BBT). There was an inverse correlation for ppMHR with all-cause mortality, with significant attenuation by BBT (per 10 percent ppMHR, hazard ratio: no BBT, 0.80 versus BBT, 0.89). The adjusted mortality rate was similar for patients on BBT who achieved 65 percent ppMHR versus those not on BBT who achieved 85 percent ppMHR. The prognostic value of ppMHR was further attenuated by estimated exercise capacity (per 10 percent ppMHR, hazard ratio: no BBT, 0.88 versus BBT, 0.95).
"In conclusion, the prognostic value of ppMHR was significantly attenuated by BBT," the authors write. "For patients on BBT, a lower threshold of 65 percent ppMHR may be considered for determining worsened prognosis."
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