Using chronotropic response as a reference, study authors from Japan investigated the potential influence of exercise-induced heart rate on cardiac output reserve and exercise capacity among a cohort of patients with heart failure with preserved ejection fraction (HFpEF).
Neither exercise capacity nor cardiac output reserve were impaired in patients with heart failure with preserved ejection fraction (HFpEF) following a bicycle exercise echocardiography and expired gas analysis, despite reduced diastolic filling time, according to study findings published in Journal of the American Heart Association.
“We sought to determine the association between heart rate, diastolic filling time, hemodynamics, and exercise capacity in HFpEF,” the authors wrote.
The 173 study participants were divided into 2 groups: 66 were in the group who had HFpEF and 107 were in the non-HF cohort. They underwent exercise stress cardiography at the echocardiographic laboratory of Gunma University Hospital, Maebashi, Japan, between October 2019 and September 2021. The stress test consisted of 20-W increments of 3 minutes each until subject-reported exhaustion. Control group participants could not have a cardiac-related cause of dyspnea.
Overall total median peak exercise workload was 33% lower among the HFpEF cohort vs the control group, at 40 (range, 40-60) vs 60 (range, 40-80) and mean exercise duration was 13% shorter, at 532 (178) vs 614 (196) seconds. However, mean respiratory exchange ratios were similar: 1.12 (0.15) vs 1.10 (0.17), respectively. Further, when considering the workload performed, effort and dyspnea median scores were higher in the HFpEF cohort vs the control group: 0.32 (range, 0.25-0.43) vs 0.25 (range, 0.20-0.32) and 0.13 (range, 0.08-0.18) vs 0.09 (range, 0.05-0.13), respectively.
Patients in the HFpEF cohort were older than controls (mean [SD] age, 74  vs 63  years), had a higher rate of hypertension (83% vs 66%), had quadruple the rate of β-blocker use (33% vs 7%), and had a reduced estimated glomerular filtration rate (63  vs 67  mL/min/1.73 m2). In addition, their mean baseline E-wave and A-wave were elevated compared with the control group:
On a scale of 0 to 60 W, overlap time continually increased for both groups concurrent with a rise in heart rate, with the control group numbers being slightly higher than the HFpEF group at all points (0, 20, 40, 60 W). This overlap time increase indicated a shorter diastolic filling time.
In turn, during peak exercise, the higher heart rate in both groups had a positive correlation with higher cardiac output (r = 0.51; P < .0001) and oxygen consumption (r = 0.50; P < .0001). In addition, the shortened diastolic filling time had a positive correlation with higher cardiac output (r = 0.47; P < .0001), as well as peak oxygen consumption (r = 0.38; P = .007).
There was also a positive relationship seen between longer overlap time and both mitral A velocity (r = 0.53; P < .0001) and left atrial booster pump strain (r = 0.42; P < .0001).
“These data suggest that shortening the diastolic filling interval in tandem with increased heart rate during exercise does not limit cardiac output reserve or exercise capacity in patients with HFpEF,” the authors wrote. “Our data indicate a compensatory mechanism for the reduction in the diastolic filling period by enhancing left atrial contractile function.”
They also note that because recent research indicates β-blockers may worsen chronotropic response to cardiac output–limiting exercise and increase left ventricular wall stress, the option to stop their use among patients with reduced exercise capacity and chronotropic incompetence should be investigated.
“Further studies are required to advance our understanding of the underlying pathophysiological mechanisms and to explore optimal treatment in this syndrome,” they concluded.
Kagami K, Obokata M, Harada T, et al. Diastolic filling time, chronotropic response, and exercise capacity in heart failure and preserved ejection fraction with sinus rhythm. J Am Heart Assoc. Published online June 29, 2022. doi:10.1161/JAHA.121.026009