Defining the electrocardiographic and echocardiographic abnormalities in a population of older adults with cardiovascular disease in rural south africa

Abstract

Abstract Background The African continent is undergoing an epidemiologic transition from infectious to cardiovascular (CV) diseases. National health systems face a critical shortage of population-level data to target the growing burden of hypertension (HTN). Very little is known on the impact of HTN on the rural population in many African countries, where over 85% of the rural population will migrate to cities and shape the modern CV disease spectrum of Africa in the next decade. Purpose To characterize the prevalence of HTN and HTN-related EKG and TTE abnormalities in a rural cohort in South Africa (n=5,059). Methods Between 2014 and 2015, 804 EKGs and 158 TTEs were performed on participants aged 40 or older randomly sampled from a longitudinal cohort residing in the Agincourt sub-district of rural South Africa. EKGs and TTEs were interpreted by two blinded physicians, and clinically meaningful variables defined using the Minnesota code (EKG) and European Association of Cardiovascular Imaging guidelines (TTE). Chi-square tests were conducted to define the association of EKG/TTE abnormalities with HTN, and stratify by gender. Results Over 55% of the sample (n=810) met blood pressure criteria for HTN, with a high prevalence of obesity (29%). On EKG, 36.5% participants had left ventricular hypertrophy (LVH), 13.6% T wave abnormalities, 7.5% Q wave abnormalities and 18.8% prolonged QT interval. Males (n=291) had more LVH (45% vs 30.8%, p<0.01) and Q wave abnormalities (10% vs 5.9%, p=0.04) than females. Instead, females (n=438) had more prolonged QT intervals (28.8% vs 21%, p=0.02). Compared to those without HTN, participants with HTN had more LVH (45.4% vs 22.1%, p<0.01), ST segment abnormalities (17.4% vs 10.7%, p<0.01) and prolonged QT interval (23.4% vs 11.4%, p<0.01). On TTE, there was a high prevalence of moderate (31%) / severe (25.8%) diastolic dysfunction, and concentric LVH (31.6%). Females had more concentric LVH (40.8% vs 13.5%, p<0.01), and high relative wall thickness (70% vs 18.1%, p<0.01) than males. Participants with HTN had more concentric LVH (42.5% vs 8.2%, p<0.01), LV mass (58.5% vs 20.4%, p<0.01) and LV mass index (52.8% vs 30.6%, p<0.01), than those without HTN. Conclusions The rural population in South Africa is already affected by a high burden of HTN and high obesity levels. Within this cohort, patients with HTN have significantly more EKG and TTE abnormalities that predict adverse CV outcomes. EKG and TTE evaluation can be used to identify high-risk groups that national health systems should prioritize with frequent monitoring and more aggressive medical treatment. Funding Acknowledgement Type of funding source: Private hospital(s). Main funding source(s): Brigham and Women's Hospital