Abstract
Ideal heart rate (HR), particularly for those with heart failure with preserved ejection fraction (HFpEF), remains unknown. We hypothesized that cardiac output would be maximum when the overlap between E-wave and A-wave at the trans-mitral flow is "zero" in the Doppler echocardiography. We retrospectively investigated the association among the overlap length between two waves, actual HR, and other echocardiographic parameters to construct a formula for estimating theoretically ideal HR among those with HFpEF. In total, 48 HFpEF patients were included (70-year-olds, 18 males). Given the results of multivariate linear regression analyses, the overlap length was estimated as follows: -1,050 + 8.4 × (HR [bpm]) + 0.6 × (deceleration time [millisecond]) + 1.7 × (A-width [millisecond]), which had a strong agreement with the actually measured overlap length (r = 0.86, P < 0.001). Theoretically ideal HR was calculated by substituting zero into the estimated overlap length as follows: 125 − 0.07 × (deceleration time [millisecond]) − 0.20 × (A-width [millisecond]). In the validation cohort including another 143 HFpEF patients, the estimated overlap using the formula again had a strong agreement with the actually measured overlap (r = 0.72, P < 0.001). In this study, we proposed a novel formula for calculating theoretically ideal HR, consisting of deceleration time and A-width, in the HFpEF cohort. Clinical implication to optimize the HR targeting the theoretically ideal HR should be investigated in prospective studies.
