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 American Journal of Cardiology.

Rupert K. Hung, MD, 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 9259 deaths during follow-up. BBT correlated with an 8% lower adjusted achieved ppMHR (91% vs 83% for no BBT vs BBT). There was an inverse correlation for ppMHR with all-cause mortality, with significant attenuation by BBT (per 10% ppMHR; hazard ratio [HR]: no BBT, 0.80 vs BBT, 0.89). The adjusted mortality rate was similar for patients on BBT who achieved 65% ppMHR vs those not on BBT who achieved 85% ppMHR. The prognostic value of ppMHR was further attenuated by estimated exercise capacity (per 10% ppMHR; HR: no BBT, 0.88 vs BBT, 0.95).


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“In conclusion, the prognostic value of ppMHR was significantly attenuated by BBT,” the authors wrote. “For patients on BBT, a lower threshold of 65% ppMHR may be considered for determining worsened prognosis.”

Reference

Hung RK, Al-Mallah MH, Whelton SP, et al. Effect of beta-blocker therapy, maximal heart rate, and exercise capacity during stress testing on long-term survival (from the Henry Ford Exercise Testing Project). Am J Cardiol. 2016;118(11):1751-1757. doi:10.1016.j.amjcard.2016.08.060.