Hypertension and Infection Underlies Heart Disease in Africa

November 22, 2011

November 21, 2011 (Orlando, Florida) — Identifying and treating high blood pressure in sub-Saharan Africa and improving the uptake of evidence-based therapies for heart failure would bring the most benefit in terms of tackling heart disease in the continent, new data indicate.

Dr Bongani M Mayosi

Also of key importance is treating sore throat with penicillin in children to prevent development of rheumatic heart disease and the use of penicillin prophylaxis as secondary prevention for this disease, together with the prevention and treatment of HIV infection, Dr Bongani M Mayosi (University of Cape Town, South Africa) told attendees at the American Heart Association 2011 Scientific Sessions last week.

During a session entitled "Focus on CVD in African populations," Mayosi presented a first look at some data from the multicenter Sub-Saharan Africa Survey of Heart Failure (THESUS-HF)acute heart-failure registry, which he explained looks at "contemporary practice" in 12 sub-Saharan African countries. What the results reveal, he said, is that most of the work will involve "translation of what we already know to get it into policies, into programs, and into practice; that's where the emphasis should be."

And he stressed that while the powers that be are busy dividing disease burden into infectious and noninfectious, there can be no such distinction in Africa, because the two are so strongly interrelated. "In the region that I work, this idea that there are communicable and noncommunicable diseases is a bit of a fallacy, because my patients present with both of those diseases, and we need to treat them in a combined type of approach."

Hypertension Is Cause of 40% of Acute HF Admissions in Africa

Mayosi explained that most prior work to have examined causes of heart failure in Africa is based mainly on statistics from the pre–HIV-infection period. "We lamented the fact that there wasn't any good information from the sub-Saharan Africa region, in particular on heart disease and specifically on heart failure. We said the time was right for action, to try to understand what is happening, because the field is full of opinions rather than facts," he observed.

The THESUS-HF registry recruited 1006 patients with acute HF admitted to the hospital in nine countries over an 18-month period. Enrollment ranged from 430 patients in Nigeria to just 10 in Ethiopia. Other contributors included Uganda, South Africa, Cameroon, Mozambique, Sudan, Kenya, and Senegal.

Countries participating in the THESUS-HF registry Source: Dr Bongani M Mayosi

[ Click here for a larger view]

Hypertension emerged as the dominant cause of admission, with 40% of cases having hypertensive heart disease and heart failure, said Mayosi.

Rheumatic heart disease "is still very important," accounting for 15% of cases, and idiopathic unexplained cardiomyopathy explained about 14%, he noted. Other principal causes of admission were peripartum cardiomyopathy, at 7.6%; pericarditis--mainly caused by tuberculosis, at about 5%; and HIV-associated cardiomyopathy, which accounted for 2.4% of cases.

Much Room for Improvement in Treatment of Hypertension, HF

The researchers then looked at how the patients were treated and followed them for six months. Uptake of ACE inhibitors ran at 77%, increasing to 85% during follow-up, but beta blockers were employed "much less," with only a 50% uptake even during follow-up, said Mayosi. Diuretics were used at a low level to begin with, although this improved, while use of the combination of hydralazine and nitrates, which Mayosi noted has "been shown to be particularly effective in patients of African descent," was "extremely low," as was the use of statins.

This idea that there are communicable and noncommunicable diseases is a bit of a fallacy, because my patients present with both of those diseases, and we need to treat them in a combined approach.

In contrast, and "a surprise," was the high use of aspirin, he said, despite the fact that ischemic heart failure "was relatively low," with only 8% of patients in the THESUS-HF registry listed as having ischemic heart disease, he noted, adding also that only 20% had atrial fibrillation.

Around 16% of patients in the registry had died at six months of follow-up, with high white blood cell count, high creatinine levels, and gross heart failure all indicative of an increased risk of death as well as HIV infection, "which was clearly associated with mortality," said Mayosi.

He noted some weaknesses of the registry: "Very few patients were subjected to coronary angiography," with diagnosis, for the most part, being made on clinical grounds. And patients with cancer were not ruled out, because the malignancy was often detected only during follow-up, "but this was something we ought to have paid attention to," he observed.

Unique Opportunity to Prevent Atherosclerotic Disease in the Sub-Sahara

"It is not difficult, based on these data, to see where to put the emphasis in terms of primary prevention, and the big three that one might focus on would clearly be the identification of high blood pressure, the prevention of rheumatic heart disease, and preventing HIV infection.

None of the interventions that have been shown to have a survival effect in heart failure are really used to levels that we would expect.

"When it comes to people who are already affected with heart disease, we need to increase the uptake of evidence-based therapies, so there needs to be work to really get what we already know into practice. These data show there is reasonable use of ACE inhibitors, but none of the interventions that have been shown to have a survival effect in heart failure are really used to levels that we would expect to be acceptable," Mayosi said. "So there is a lot of room for improvement, particularly the use of beta blockers.

"There is also a need to ensure that patients with rheumatic heart disease--and we have large numbers of these patients--are on penicillin prophylaxis to prevent subsequent events from occurring, and there is anecdotal evidence to suggest that perhaps antiretroviral therapy [for HIV] in the African setting is also associated with less occurrence of heart disease."

And there are important implications for research, said Mayosi. The role of screening of blood pressure is vitally important, "and of course other risk factors for atherosclerotic disease." In fact, he stressed, "in sub-Saharan Africa, there is a real opportunity for primordial prevention of atherosclerotic disease because it occurs at a relatively low level compared with other parts of the world.

"We also need to be identifying the etiology and treatment of some of the more obscure forms of heart disease, such as the cardiomyopathies--both in terms of unexplained dilated cardiomyopathy as well as peripartum cardiomyopathy--and endomyocardial fibrosis," he concluded.

Mayosi did not report any conflicts of interest.


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