Spectrum of heart failure in sub-Saharan Africa: data from a tertiary hospital-based registry in the eastern center of Burkina Faso

Introduction Heart failure (HF) is a strong contributor to non-communicable diseases burden in sub-Saharan Africa (SSA). Few studies have addressed the pattern of HF in Burkina Faso. Methods We conducted a prospective cohort study in patients with acute HF in the Regional Hospital Center of Tenkodogo, eastern region of Burkina Faso. Patients were consecutively enrolled from 1st January 2015 to 31st December 2016 and followed up until June 2017. Primary outcome of interest was mortality. Results Overall 318 of 1805 cardiac cases presented with acute HF (17.62 %). Of the 298 patients included in the analysis process, 239 had de novo HF and 150 were male. The mean age was 58.56 ± 18.54 years. Eighty-eight patients presented with atrial fibrillation. The mean left ventricular ejection fraction (LVEF) was 38.20 ± 12.85 % with reduced ejection fraction (LVEF < 40%) accounting for 59.73% of the cases. Most of the study patients lived in rural areas. Hypertensive heart disease (50.34%) and idiopathic dilated cardiomyopathy (19.80%) were the leading causes of HF. Most patients received renin-angiotensin system blockers contrasting with a lower prescription rate of beta-blockers (99% versus 18.79% respectively). The incidence of all-cause mortality was 31 percent patients-years. Conclusion Heart failure is frequent in SSA, affecting patients at younger age. Predominantly of non-ischemic cause, commonly hypertensive, the disease is associated with high mortality.


Introduction
Heart failure (HF) is a major public health and growing problem, affecting about 26 million people worldwide [1] including low-income countries particularly sub-Saharan Africa (SSA) [2,3]. The prevalence of HF is approximately 1-2% of the adult population in developed countries with well-established population-based registries, rising to ≥ 10% among people over 70 years of age [2][3][4][5]. This prevalence is going to scale up because of the ageing population and improvements in treatment [6]. HF is associated with high morbidity and mortality despite progress in its management. Expenditure of HF-related health care is estimated to be about US$ 100 billion in 2012 [7], with total costs expected to strongly increase in the forthcoming decades [6].
Data on HF in sub-Saharan Africa (SSA) are still scarce and mostly available for urban hospital-based settings [8]. Therefore, the present study aimed to assess the clinical epidemiology and long-term prognosis of HF in the eastern center region of Burkina Faso, West Africa.

Methods
Study setting: this study was conducted in the cardiology unit, Department of Medicine, Regional Hospital Center (RHC) of Tenkodogo, Tenkodogo, Burkina Faso. The RHC of Tenkodogo is the unique tertiary health care center that covers a dry orchard savannah region populated of about 1.4 million inhabitants, almost constituted by subsistence farmers. Tenkodogo, the capital town of the easterncenter region is located at 188 kilometers from the political capital, Ouagadougou. Since the opening of the RHC, the first cardiologist was assigned in 2015. Operational definitions: kidney dysfunction was defined as an estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m 2 .

Procedures
Corrected QT interval was reported by measuring manually the RR and QT intervals from the 12-lead ECG. Thereafter, Bazett's formula Additionally, telephone contact was used to ascertain the survival status from patients or their relatives as national mortality registry is so far not available countrywide.
Outcomes: the primary outcome of interest was all-cause mortality through follow-up period. Subsequently, readmission for acute decompensation of HF and stroke were assessed. The immediate cause of death was also recorded and categorized as either cardiac, non-cardiac or unknown.
Statistical analysis: data were analyzed using R software.
Continuous variables were expressed as means ± standard deviation (SD) and categorical variables as percentage. Differences between groups were assessed using Chi square or student test as appropriate.
Survival rates over time were provided using the Kaplan-Meier method. A value of p < 0.05 was considered statistically significant.
Ethic aspects: the study was approved by the institution´s ethics review board. The board waived the need for signed written informed consent due to illiteracy of most study participants and also that collected data were non-invasive and obtained from routine practice.
Only oral informed consent was required. The study was carried out in accordance with the principles of the declaration of Helsinki [17].

Results
Overall, 1805 patients attended the cardiology unit during the recruitment period, (both outpatients and inpatients). AHF was reported in 318 patients accounting for 17.62% of all admissions.
Twenty patients were excluded from the final analysis process (inhospital death before enrolment: 10, uncomplete data: 3, moved to neighboring countries: 3 and lost to follow-up: 4 One hundred and seventy-eight patients (59.73%) presented with kidney dysfunction. HFrEF was found in 178 patients. Table 2 shows baseline laboratory findings of the study patients.
Etiologies and medications prescribed to study patients are shown in suggesting that once HF occurs, it may have a distinct course independent of patient characteristics [29].
Our study is limited by its monocentric aspect; hence data extrapolation nationwide has weakened. Definitely, only patients from "privileged" background who could afford cardiology care and/or those with overt HF attended the cardiology unit and then were included. Therefore, patients with less symptomatic cardiovascular diseases or asymptomatic HF in non-cardiac units and in the community, may have been excluded.

Conclusion
The prevalence of heart failure is substantial in our setting. It affects patients at younger age with hypertensive heart disease being the most common cause. The disease is associated with poor long-term outcome. We must continue to strike for the reduction of the burden of HF through early detection and adequate treatment of its modifiable risk factors (eg. hypertension, smoking, rheumatic fever) at the community level. A population-based study is needed to better characterize the scope of HF in this community.
What is known about this topic  HF is an emerging public health concern in SSA with hypertension being the most prevalent risk factor, mostly in urban areas;  HF is associated with high long-term mortality.

What this study adds
 HF is not rare even in less urbanized regions of SSA;  The pattern of the disease is burdened with the lack of lowcost specific medications in a context of poverty;  Therefore, policymakers should set-up HF prevention strategies and make available essential drugs for cardiovascular treatment in public health pharmacies nationwide.

Competing interests
The authors declare no competing interests.

Acknowledgments
We are grateful to study subjects for their participation. Many thanks to the staff members of the Department of Medicine, RHC of Tenkodogo for their technical support during the study.