An Emerging Picture of Heart Failure in Africa

November 24, 2008

November 24, 2008 (Johannesburg, South Africa) — One of the largest and most comprehensive studies of heart failure to date in Africa has shown that the disease is a big problem and that although the traditional causes of HF--which differ from those seen in Western nations--still predominate, there are signs that the range of etiologies is broadening [1]. This has important implications for primary- and secondary-prevention strategies, say Dr Simon Stewart (Diabetes Research Institute, Melbourne, Australia) and colleagues from South Africa in a report published online November 24, 2008 in Circulation.

Stewart et al found that the contemporary HF patients they studied in South Africa were younger, on average, than those seen in the West and more likely to be female. The major contributing factors were those traditionally associated with HF in sub-Saharan Africa--uncontrolled hypertension, valve disorders, and idiopathic cardiomyopathy--but there were also signs that increasing urbanization is starting to change the characteristics of HF seen. In addition, a high proportion of right heart failure was encountered--27% of the total--which is 10 times greater than the incidence of right HF reported in Western nations and will require a unique approach to intervention, they note.

Senior author Dr Karen Sliwa (Chris Hani Baragwanath Hospital, Johannesburg, South Africa) told heartwire : "For the first time, we have characterized HF in South Africa, and probably in Africa in general, and documented that it's a big problem. That was not known before. We have shown that this high number of cases of heart failure is due to a combination of diseases of lifestyle--such as those you see around the world--and diseases of poverty, such as rheumatic heart disease that is not being picked up early enough and is leading to HF. Thus, there are important implications for how to treat and prevent HF in Africa."

Hypertensive HF is Still the Most Common Diagnosis

Stewart et al prospectively collected detailed demographic and clinical data from 844 de novo HF presentations out of 1960 cases of HF in 2006 in the Heart of Soweto Study, a registry at Chris Hani Baragwanath Hospital. The hospital serves 1.1 million in the black African township of Soweto.

The mean age of those with HF was 55 years, and 57% were women. Of those with HF, 88% were black Africans, and the most common diagnoses were hypertensive HF (281, 33%), idiopathic dilated cardiomyopathy (237, 28%), and right HF (225, 27%). And a significant proportion of the right HF cases were isolated, due to, for example, chronic obstructive pulmonary disease (COPD).

"These data confirm that black African patients are particularly vulnerable to HF caused by untreated high blood pressure," says Stewart in an AHA statement.

Sliwa agrees, saying that resources must be put into hypertension screening programs. "There is very poor access to healthcare generally, and things are not picked up early enough. We have no screening programs for hypertension in the workplace, for example, so people come very late to the hospital, when their hypertension is already leading to HF."

Right HF Down to Pollution? Unique Interventions Required

Sliwa continued: "We saw very specific reasons here for why people develop cardiomyopathy that you don’t see in other parts of the world." As well as the high rate of hypertensive HF, there was a lot of idiopathic cardiomyopathy, "which is probably postviral," she noted, and "an extremely high" proportion of peripartum cardiomyopathy--the cause of 29 of the 844 new cases of HF.

"We also found an unusually high number of cases of right HF and isolated right HF, and we still don't know exactly where this is from, but it's probably due to indoor cooking, passive smoking, air pollution, and/or poorly treated asthma," she added.

Stewart concurs: "Given the very high number of cases of isolated right HF reflecting damage to the pulmonary vessels and lungs, even in nonsmokers, it is likely that air pollution--both occupational and domestic--plays a leading role. This will require major public-health initiatives, particularly as Soweto, like many other developing regions, suffers from major air pollution."

"The treatment of this form of HF is underdeveloped and will required further research," he notes, adding that this will require the development of specific therapies for a form of HF rarely reported and managed in high-income countries.

Threat of Epidemiological Transition; Tailored Screening Needed

In the study, black Africans had less ischemic cardiomyopathy (adjusted odds ratio 0.12) but more idiopathic and other causes of cardiomyopathy (OR 4.80). The researchers say that although the very low number of cases they saw due to ischemic causes is totally different from that seen in Western nations--where up to 80% of cases of HF have ischemic causes--the proportion of HF due to ischemic causes is changing, now standing at 9% of cases in this study compared with 2% in earlier data sets. This likely reflects the urbanization that is happening in South Africa, says Stewart.

"The underlying background of this study is the epidemiological transition in many urban regions in Africa, including Soweto, where the double threat of malnourishment and infection have now been joined by more affluent pathways to disease," he says.

Hence, the data have "important clinical and public-health implications for urban Africa and other communities in epidemiological transition. Treatment strategies need to keep pace with the changing etiology of HF and preventive strategies need to focus on both old and new antecedents of HF," he and his colleagues observe.

"There is a clear need to develop African-specific prevention programs that optimize the detection and management of hypertension in addition to targeting those most at risk of developing peripartum cardiomyopathies and HIV-related cardiomyopathy," they stress. In addition, screening for rheumatic heart disease in children and gender-specific programs for screening and managing HF in Soweto should also be a priority, they conclude.

The registry was supported by unconditional research grants from Adcock-Ingram, the Medtronic Foundation, and Servier.

  1. redominance of heart failure in the Heart of Soweto Study cohort. Emerging challenges for urban African communities. Circulation 2008; DOI: 10.1161/CIRCULATIONAHA.108.786244. Available at: http://circ.ahajournals.org.

 

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