Effect of beta-blocker-induced heart rate lowering on left atrial function in patients with hypertension and recurrent atrial fibrillation
Authors: Kokhan E , Kiyakbaev G , Ozova E , Romanova V , Kobalava Z.H 
Published: November 2020

Abstract

Background
The ESC/ESH Hypertension Guidelines identify high resting heart rate (HR) as a risk factor in patients with hypertension. However, it is not known, whether pharmacological reduction in HR is associated with improvement of prognosis in patients with preserved ejection fraction. In retrospective studies beta blockers (BBs) use was associated with impaired left atrial (LA) function in hypertension, but the prospective data, concerning this relationship is scarce.

Purpose
To assess the effects of HR reduction with BBs on LA function in hypertensive patients with recurrent (rare paroxysms) mild symptomatic atrial fibrillation.

Methods
Open prospective trial included 91 patients with hypertension, elevated heart rate (≥80 bpm) and recurrent atrial fibrillation (EHRA 2A or less) with rare paroxysms to receive BBs with a target HR (sinus rhythm) of less or greater than 70 bpm. All the patients underwent an echocardiogram at baseline and at the end of the study. Conventional echo measures and extended LA measures, including the minimal and maximal LA volumes (LAVmin and LAVmax) and LA emptying fraction (LAEF) were performed. Patients were followed for 4 months on the change and assessed for primary endpoint of median LAEF measurement at the end of the study.

Results
47 patients were randomized to group with a target HR of ≤70 bpm and 44 patients to &gt;70 bmp. Among them, 44 and 41 patients completed the study (2 had AF at the final visit; 4 were lost to follow-up).
Baseline median HR was 77 (75; 80) bpm. After 4.4 months of treatment, median HR was 62 (60; 67) bmp in ≤70 group and 73 (72; 76) bpm in &gt;70 group (p&lt;0.001). There were no intergroup differences in antihypertensive therapy and systolic (129 vs 130 mmHg; p=0.32) and diastolic (78 vs 78 mmHg; p=0.53) blood pressure.
At the end of the study patients in ≤70 group had significantly lower LAEF compared with &gt;70 group (37 vs 42%; p=0.01); a median change was −6.5 (−9.75; −3.9)% and −0.27 (−1.78; 1.18)%, respectively [estimated between group difference −5.89%; 95% confidence interval (CI): −8.06 to −3.71%]. Despite similar indices of LAVmin (22 vs 19 ml/m2; p=0.66) and LAVmax (38 vs 37 ml/m2), comparison of changes showed significant differences: median change LAVmin: 1.3 ml/m2 in ≤70 vs 0.5 ml/m2 in &gt;70 groups (estimated between group difference −1.29%; 95% CI: −2.07 to −0.5%) and ΔLAVmax: 1.8 ml/m2 in ≤70 vs 1 ml/m2 in &gt;70 groups (estimated between group difference −1.51%; 95% CI: −2.73 to −0.28%). E/E' and left ventricle mass index did not differ between study groups at the end of the study, but E' was significantly lower in the ≤70 group (7 vs 8.3 cm/s; p=0.04).

Conclusion
BB-induced HR lowering with a target ≤70 bpm significantly reduced LA function as compared to lenient target HR (&gt;70 bpm). Although elevated HR is associated with adverse outcomes in patients with hypertension, excess HR lowering with BBs might not be beneficial in this group.

Funding Acknowledgement
Type of funding source: None