Performance of Fixed Heart Rate Increment Targets of 20 vs 30 Beats per Minute for Exercise Rehabilitation Prescription in Outpatients With Heart Failure

Abstract

Background: Patients with heart failure (HF) should exercise at 40%-60% heart rate reserve (HRR) during the first 3 weeks of an outpatient cardiac rehabilitation (CR) program and at 50%-80% HRR thereafter. Arbitrary methods to prescribe exercise intensity such as resting HR (RHR) plus 20 or 30 beats per minute (bpm) (RHR + 20 or RHR + 30) are recommended for inpatients after a myocardial infarction or those recovering from heart surgery. This approach has been repurposed by outpatient CR programs to prescribe exercise intensity for patients with HF, yet its efficacy has not been evaluated.

Methods: We examined the appropriateness of RHR + 20/30 for prescribing exercise intensity and improving functional capacity for 55 patients with HF in an outpatient CR program. RHR + 20/30 values were compared to % HRR derived from peak exercise testing in patients with HF. Changes in functional capacity as measured by 6-minute walk test (6MWT) distance, and differences in ratings of perceived exertion (RPE), were examined between patients exercising at RHR + 20-29 and those exercising at RHR + ≥ 30.

Results: During weeks 1-3 and exercise at RHR + 20, 26% of participants would exercise at 40%-60% HRR. At RHR + 30, 38% would exercise at 40%-60% HRR. During weeks 4-12 and exercise at RHR + 20, 20% of participants would exercise at 50%-80% HRR. At RHR + 30, 41% would exercise at 50%-80% HRR. A smaller change in 6MWT distance was observed in participants exercising at RHR + 20-29 than in those exercising at RHR + ≥ 30 (Δ86.6 ± 70.3 vs Δ135.8 ± 73.7 m; P = 0.005). No differences in RPE were observed between participants exercising at RHR + 20-29 and those exercising at RHR + ≥ 30 (P > 0.05).

Conclusions: RHR + 30 was more effective than RHR + 20 in assisting outpatients with HF achieve recommended exercise intensities and improve functional capacity.