BACKGROUND AND AIMS: Chronotropic incompetence (CI) is common in heart failure with preserved ejection fraction (HFpEF) and contributes to reduced exercise tolerance. However, the effects of exercise training on CI in HFpEF remain unknown. We aimed to assess the effect of different exercise training intensities on chronotropic reserve in HFpEF.

METHODS: This is a subanalysis of the OptimEx-Clin trial. Patients with HFpEF were randomized to high-intensity interval training (HIIT), moderate continuous training (MCT) or guideline control (GC). CI was assessed during cardiopulmonary exercise testing at baseline and 3 months. CI was defined as a chronotropic index ≤0.62 in patients on negative chronotropic medications and ≤0.80 in others.

RESULTS: Among 175 patients with HFpEF (66% female, mean age 70±8 years), 144 completed follow-up. CI was present in 51% and was associated with lower peak oxygen uptake (16.5±4.2 vs. 21.1±5.2 mL/kg/min, p<.001), lower peak workload (89±28 vs. 116±39 W, p<.001), and poorer ventilatory efficiency (35.2±7.1 vs. 32.6±6.8, p=.014) at baseline. HIIT and MCT did not improve chronotropic index, %predicted peak heart rate, nor CI prevalence after 3 months (all p>.500), and adjusting for negative chronotropic drug use did not change results. Nevertheless, HIIT and MCT improved V̇O2peak and workload (p<.001) versus GC, regardless of the presence of CI.

CONCLUSION: In elderly patients with HFpEF, neither HIIT nor MCT during 3 months significantly improved chronotropic reserve or reduced CI prevalence, but exercise capacity was improved.