Predicting Maximal HR in Heart Failure Patients on ß-Blockade Therapy

• Autores: Steven J. Keteyian, Dalane W. Kitzman, F. Zannad, Joel Landzberg, J. Malcolm Arnold
• Localización: Medicine & Science in Sports & exercise: Official Journal of the American College of Sports Medicine, ISSN 0195-9131, Vol. 44, Nº. 3, 2012, págs. 371-376
• Idioma: inglés
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• Resumen

  • Purpose: Standards for estimating maximal HR are important when interpreting the adequacy of physiologic stress during exercise testing, assessing chronotropic response, and prescribing an exercise training regimen. The equation 220 - age is used to estimate maximum HR; however, it overestimates measured maximal HR in patients taking ß-adrenergic blockade (ßB) therapy. This study developed and validated a practical equation to predict maximal HR in patients with heart failure (HF) taking ßB therapy.

    Methods: Data from symptom-limited exercise tests completed on patients with systolic HF participating in the Heart Failure: A Controlled Trial Investigating Outcomes of Exercise Training trial and taking a ßB agent were used to develop a simplified equation, which was validated using bootstrapping.

    Results: The simplified derived equation was 119 + 0.5 (resting HR) - 0.5 (age) - (0, if test was completed using a treadmill; 5, if using a stationary bike). The R2 and SEE were 0.28 and 18 beats·min-1, respectively. Validation of this equation yielded a mean R2 and SEE of 0.28 and 18 beats·min-1, respectively. For the equation 220 - age, the R2 was -2.93, and the SEE was 43 beats·min-1.

    Conclusions: We report a valid and simple population-specific equation for estimating peak HR in patients with HF taking ßB therapy. This equation should be helpful when evaluating chronotropic response or assessing if a maximum effort was provided during exercise testing. We caution, however, that the magnitude of the variation (SEE = 18 beats·min-1) associated with this prediction equation may make it impractical when prescribing exercise intensity.