The clinical and biochemical effects of atrial fibrillation on heart failure with reduced ejection fraction; a sub-saharan African perspective
Authors: Mboweni N , Tsabedze N , Toman M , Maseko M 
Published: October 2022

Abstract

Background
Sub Saharan Africa (SSA) has seen one of the sharpest increases in cardiovascular disease-related mortality. This increase is evidenced by a growing burden of heart failure and atrial fibrillation (AF) risk factors. Atrial fibrillation is a common comorbidity of heart failure with reduced ejection fraction (HFrEF) which predisposes to an increased risk of morbidity and mortality. Studies done in high income countries (HIC) suggest that there may be an essential role for ethnic differences. However, in the absence of accurate epidemiological data in Sub-Saharan Africa, this cannot be proven. To date, there has never been a prospective systematic description of patients with HFrEF/AF and HFrEF/sinus rhythm (SR).

Aim
Our study aimed to describe the clinical and biochemical profile of patients with HFrEF/AF and HFrEF/SR in a Sub-Saharan African cohort.

Methods
The study was conducted inthe division of our Academic Hospital in South Africa. We enrolled 141 patients, consecutively, with HFrEF. Baseline clinical characteristics and exploratory biomarkers were recorded. All participants underwent comprehensive echocardiography. Novel left atrial strain was measured using 2D-speckle tracking echocardiography. These values were compared between patients in SR and in AF.

Results
The prevalence of AF was 21.38%. Hypertensive heart disease was the leading cause of HFrEF (36%). HFrEF/AF patients were significantly older (66.7±11.9) than those in SR (53.7±14.4) (p=0.000) with significantly different racial proportions (p=0.001). Coronary artery disease was prevalent in patients with HFrEF/AF. Patients with HFrEF/AF had significantly lower Kansas City Cardiomyopathy Questionnaire scores (29.83±15.27) compared to those in SR (44.26±16.30) (p=0.000) as well as worsening functional class (NYHA III–IV; 64.3% vs 22.7%, p=0.000). Measured levels of sST2 were greater in HFrEF/AF patients 40.45ng/mL (17.6–68.6) vs 20.8 (7.9–44.0) in HFrEF/SR (p=0.031). Patients with HFrEF/AF had a significantly greater left atrial volume (ml) (83.9 [64–99.9]) than those with HFrEF/SR (61.53±25.46) (p=0.038). Left atrial strain reservoir function (%) was significantly lower in patients with HFrEF/AF (29.00±13.60) compared to those with HFrEF/SR (41.56±15.46) (p=0.0004)

Conclusion
Our findings demonstrate that patients with HFrEF/AF are older than those in SR but much younger compared to patients in HICs. Hypertensive heart disease is a major cause of HFrEF in South Africa. We demonstrate that patients with HFrEF/AF are clinically worse off than those with HFrEF/SR. Atrial fibrillation is a marker of fibrosis and disease severity in HFrEF. Patients with HFrEF/AF had elevated sST2 levels a more deformed left atrium morphologically and poor tissue doppler function. On strain imaging, HFrEF/AF patients had poor left atrial reservoir function.

Funding Acknowledgement
Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): The South African Medical Research Council