Utilizing the chronotropic response as a benchmark study, researchers from Japan examined the possible impact of heart rate-induced exercise on cardiac output reserve as well as fitness capacity in a group of patients suffering from heart failure that has preserved ejection (HFpEF).
There was no evidence that exercise capacity or the cardiac output reserve was impaired in patients suffering from heart failure that has preserved ejection (HFpEF) in the course of an exercise echocardiogram on a bicycle and the expiration of gas analyzes, even though there was a reduction in diastolic filling times as determined by study findings that were published in Journal of the American Heart Association.
“We determined the connection of heart rate and diastolic filling times hemodynamics, as well as the exercise capacity of HFpEF,” the authors have written.
The 173 participants in the study were divided into two groups: 66 were part of the group with the HFpEF while 107 were from the non-HF group. They were subjected to exercise stress cardiography in the echocardiographic laboratory at Gunma University Hospital, Maebashi, Japan, between October 2019 to September 2021. The test was comprised of 20-W intervals of 3 minutes each , until the subject reported exhaustion. The control group participants did not be suffering from a cardiac-related cause of dyspnea.
The median of the total maximum exercise load was 33% less in the HFpEF cohort than the control group, with a mean of 40 (range 40-60) and 60 (range 40-80) and the mean duration of exercise was 13% less, in 532 (178) and 614 (196) seconds. However, the mean ratios of respiratory exchange were comparable: 1.12 (0.15) vs 1.10 (0.17) and 1.10 (0.17). In addition, when analyzing the amount of work performed the effort and dyspnea mean scores were more high in the HFpEF group compared to the group that was controlled: 0.32 (range, 0.25-0.43) in comparison to 0.25 (range, 0.20-0.32) and 0.13 (range, 0.08-0.18) against 0.09 (range, 0.05-0.13) and 0.09 (range, 0.05-0.13).
Patients who were part of the HFpEF group were more senior than the controls (mean of age of 74,8 vs. the 63 years) They also had a higher incidence of hypertension (83 percent vs 66 percent) as well as a quadruple frequency of using b-blockers (33 percent vs 7%)) and also had an estimated glomerular filtration frequency (63 23 vs. 21 mL/min/1.73 1 m 2.). Additionally, their mean A-wave and E-waves were higher than those in the control group
- E-wave: (74 (26) against 65 (16) cm/s
- A-wave: (91 (27) (vs the 76 (21) cm/s
On a scale from between 0 and 60 W, the overlap time always increased for both groups in tandem with an increase in heart rate. The difference was that the numbers for the control group being just a bit higher than those of that of HFpEF group at all times (0 20-40, 40-40 60 W). This increase in overlap time indicated that diastolic filling times were shorter.
In addition, during peak exercise, the increased heart rate of both groups showed an positive correlation with greater heart rate (r = 0.51; P > .0001) and the consumption of oxygen (r equals 0.50; P = .0001). Additionally, the shorter diastolic filling duration was associated with a positive relationship to the higher output of the heart (r = 0.47; P = .0001) as well as the highest level of oxygen consumption (r is 0.38; P = .007).
Also, there was a positive relationship between the longer overlap duration and the mitral A speed (r = 0.53; P = .0001) as well as left atrial pressure (r = 0.42; P = .0001).
“These results suggest that reducing the diastolic filling time together with an increased the heart’s rate in exercise doesn’t restrict the reserve of cardiac output or the capacity to exercise in patients suffering from HFpEF,” the authors have written. “Our results suggest an explanation for the decrease in diastolic filling time by improving the left atrial contraction function.”
They also mention that as recent studies have shown that b-blockers could cause a worse chronotropic response to exercise with output limitation and can increase stress on the left ventricular wall and stress on the left ventricular wall, stopping the use of b-blockers in patients with diminished exercise capacity and/or chronotropic incompetence must be considered.
“Further studies are needed to increase in our knowledge about the pathophysiological causes and to determine the best treatment options for this condition,” they concluded.
Reference
Kagami K, Obokata M, Harada T, et al. Diastolic filling times as well as the chronotropic response and the capacity to exercise in cardiac failure as well as preserved ejection sinus rhythm. J Am Heart Assoc. Published online June 29, 2022. doi:10.1161/JAHA.121.026009
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