Soweto, South Africa - An investigation of the characteristics and burden of cardiovascular disease in an urban African community provides concrete evidence that heart disease is emerging as a threat in addition to traditional risks, such as infectious disease and malnourishment [1]. In this new registry, investigators report that heart failure is common among black Africans presenting to a tertiary-care clinic, with more than 30% having advanced heart failure, and that almost two-thirds of patients had multiple cardiovascular risk factors.

"Our data provide preliminary evidence to show the effect of epidemiological transition in this population, who face many threats to their present and future cardiac health, including a high prevalence of modifiable risk factors for atherosclerotic disease, a combination of infectious and noncommunicable forms of heart disease, and late clinical presentations," write Dr Karen Sliwa (University of the Witwatersrand, Johannesburg, South Africa) and colleagues in the March 15, 2008 issue of the Lancet.

The combination of these preventable risk factors, as well as late clinical presentations, represent challenges to improving primary- and secondary-prevention strategies, say investigators, especially for reducing the number of new cases and to improve outcomes for those with existing disease.

To date, few data exist in low-income and middle-income countries to describe the effect of cardiovascular disease as an emerging problem, the authors note. The aim of this study, known as the Heart of Soweto Study, was to create a registry capable of documenting emergent heart disease and its antecedents in the townships that constitute Soweto, South Africa.

From January 1, 2006 to December 31, 2006, investigators recorded data for 4162 patients with confirmed cardiovascular disease who were presenting for the first time to a tertiary-care center. Of these patients, 38% were newly diagnosed with cardiovascular disease, while the remaining 62% of patients were previously diagnosed and under treatment.

Overall, the investigators report that the study cohort had a broad range of cardiovascular disease and risk factors and that apart from patients with a primary diagnosis of hypertension, most cases represented "late clinical presentations with established heart disease of more than one cause." Overall, the most common diagnoses were hypertension, heart failure, valvular heart disease/dysfunction, and coronary heart disease. In addition, diabetes, renal disease, and anemia were diagnosed in some patients, while 5% were confirmed as HIV positive, although HIV testing was done only if consent was given.

The investigators report that on presentation, many patients had evidence of advanced disease, with significant dyspnea, chest pain or angina, and peripheral edema. Electrocardiographic and echocardiographic testing also showed many patients to have advanced disease, with 34% of patients having tachycardia or underlying dysfunction or structural disease. Of the 844 patients diagnosed with heart failure, 31% of these had NYHA class 3 or 4 heart failure.

The fact that so many patients had developed significant clinical disease before their first hospital visit suggest little awareness of heart disease or difficulties obtaining appropriate healthcare, according to the authors. Supporting this, they point out that most patients with hypertension and diabetes are identified only after significant organ damage has occurred.

In their paper, Sliwa and colleagues write that the new registry provides clinicians with "the opportunity to establish whether epidemiological transition in Soweto has broadened the spectrum of clinical cardiovascular disease beyond the traditional threats of rheumatic valvular heart disease, the cardiomyopathies, and tuberculous pericardial effusion (affecting 40% of patients in 2006)."

In an editorial accompanying publication of the registry's findings [2], Drs Harvey White (Auckland City Hospital, New Zealand) and Anthony Dalby (Milpark Hospital, Johannesburg, South Africa) point out that infectious disease, coronary artery disease, and HIV/AIDS, along with the reemergence of tuberculosis, together form a "triple cardiac threat," all of which contribute to an increased incidence of cardiomyopathy and heart failure.

White and Dalby note that the Heart of Soweto study includes only symptomatic patients seeking medical help and does not include those reluctant to see a doctor, those tolerating symptoms, or those treated by a traditional healer. Still, efforts that focus on lifestyle modification, early identification, and cost-effective treatment of risk factors are a step in the right direction of "blunting" this triple threat, they write.

Efforts should also be directed to controlling rheumatic fever, which can be accomplished through primary prophylaxis with better housing, less overcrowding, improved access to healthcare, and preventing recurrent infection with medication. Echocardiography could also detect rheumatic fever earlier.

"The major challenge is how to increase health resources," write White and Dalby. "A recurring theme in Africa is the absence of reliable statistics. This registry, from one of the largest urban populations of black Africans, goes a long way toward correcting that deficit in Soweto. The ongoing study will provide important insights into the prevalence of heart disease, which is the first step to the mitigation of the modern global epidemic of cardiovascular disease."