Detection Of Rheumatic Heart Disease Research Articles

High prevalence of rheumatic heart disease in Fiji detected by echocardiography screening

Rheumatic heart disease poses a huge burden for developing countries, with Pacific Island nations having among the highest prevalence reported in the world. It is recognised that echocardiography is much more sensitive than clinical examination for detection of rheumatic heart disease, but resource and cost limitations are delaying implementation of screening programmes in developing nations. Rapid echocardiography using low-cost portable machines and a non-expert operator may be a useful compromise, allowing widespread screening and control of rheumatic heart disease in developing countries. In-school echocardiography and clinical examination was carried out on primary school children (aged five to 14) in Lautoka, Fiji. All of the children with abnormal findings were then recalled for complete in-hospital clinical and echocardiographic assessment by a paediatrician with expertise in rheumatic heart disease and echocardiography. Using screening echocardiography averaging less than 4 min per patient, the prevalence of definite rheumatic heart disease detected by echocardiogram screening was 55.2 per 1000 compared with 11 per 1000 detected by clinical examination (P < 0.001). It was demonstrated that echocardiography is five times more sensitive at detecting rheumatic heart disease compared with clinical examination. A comprehensive screening programme is estimated to cost less than US$40 per patient detected. This study confirms that Fiji has the highest documented prevalence of rheumatic heart disease in the world. Rapid echocardiography has the potential to screen large numbers of patients by non-specialist operators, which encourages its use in larger scale screening and prevention strategies in developing countries.

Rheumatic heart disease and its control in the Pacific

Rheumatic fever and rheumatic heart disease continue to be a huge public-health burden on many Pacific Island countries. Prevalence reported in some nations are some of the highest seen globally, yet many countries in the region do not have national disease registers. Despite the will of many Pacific Island countries, there are a number of barriers to the implementation and sustainability of effective coordinated prevention programs, including limited funding and competing health priorities. In promising recent developments, a number of countries in the region have been able to develop or strengthen national rheumatic heart disease registers. These registers allow for more effective delivery of secondary prophylaxis, the mainstay of disease control in the Pacific. Primary prevention of rheumatic fever and screening for rheumatic heart disease are important adjunctive strategies. Recent advances in screening methods, focusing on portable echocardiography, may allow for the early detection of rheumatic heart disease in the community.

Can echocardiography be used for screening of rheumatic heart disease?

Sir, In poor and developing nations, rheumatic heart disease remains a major cause of morbidity and premature death and imposes a substantial burden on health care systems with limited budgets.(1) Secondary prevention is one of the effective tools in rheumatic heart disease. Secondary prevention relies on accurate case detection for the appropriate use of prophylactic antibiotics and regular medical surveillance. Traditionally, cases of rheumatic heart disease are identified by clinical examination only, while echocardiography is used for confirmation of the same. Almost all population-based epidemiologic surveys have relied on this strategy. Such surveys show current prevalence rates of rheumatic heart disease of approximately 1 to 5 cases per 1000 among school-age children in developing countries.(2) Echocardiography is known to be more sensitive than auscultation for the detection of pathologic valve disease. Meira et al, reported that in 34% of their patients with carditis, clinical examination after the acute phase showed normal findings, although progression to chronic sub clinical valvular disease was confirmed by echocardiography in 82% of such cases.(3) According to Marijon et al. systematic screening with echocardiography, as compared with clinical screening, reveals a much higher prevalence of rheumatic heart disease.(4) World Health Organization (WHO),(5) states that, echocardiographically diagnosed, clinically silent rheumatic valve involvement should be managed as rheumatic heart disease until proved otherwise. WHO also states that, it is important to recognize that technical expertise with color flow Doppler echocardiography is necessary to make an accurate diagnosis of sub clinical carditis and to avoid over diagnoses. In developing countries, where the majority of rheumatic fever (RF) cases occur, such expertise and facilities are available in only a limited number of centres. As a result, the impact of erroneous diagnoses of rheumatic carditis based on sub clinical echocardiographic findings should not be underestimated, nor should the potentially adverse consequences to patients and health systems in such settings. High sensitivity of Doppler echocardiography is also questionable in using it as screening test. Prevalence of carditis in RF patients is significantly higher when detected by echocardiography than that reported clinically, and the utility of a test that diagnoses a disease characteristic (such as carditis in RF) in almost every patient with RF is questionable.(5) Clinically suspected cases of rheumatic heart disease are confirmed by echocardiography, but how to confirm the cases detected by echocardiography? From statistical viewpoint, Bayes theorem states that the probability of disease following the interpretation of a diagnostic investigation (the post-test probability) is determined by two factors. Firstly, the probability of disease prior to carrying out the investigation (the pre-test probability) based on the information already available and secondly the characteristics of the test. Any decision for screening strategy should ideally entail the calculation of prior probability (i.e., prevalence) of rheumatic heart disease in a given area along with diagnostic accuracy (i.e., sensitivity and specificity) of screening criteria (clinical) or method (echocardiography) so as to have correct posterior probability of rheumatic heart disease. These are some of the issues which have to be considered before using echocardiography as screening tool for detection of rheumatic heart disease in large populations.

Rheumatic fever: the potential advantages of technology

This article sets out the clinical context of the research presented by Carapetis et al. in an accompanying article in this issue. No screening guidelines exist for early detection of rheumatic heart disease (RHD). The lack of agreed diagnostic criteria is one of the reasons why large proportions of cases in resource poor nations go untreated and are detected only when the disease has progressed to cardiac failure. Here, Poole-Wilson and Seth discuss the study carried out by Jonathan Carapetis and colleagues-a cross-sectional screening protocol in Tongan primary school children. The protocol designed by Carapetis et al. identified the highest echocardiographically confirmed prevalence of RHD reported to date. Poole-Wilson and Seth explore how modern technology, in the shape of portable echocardiography, can help to move the focus on rheumatic heart disease away from epidemiology and crude preventive programs, and towards screening programs that can effectively identify people who should receive treatment before cardiac failure occurs.

Echocardiographic screening for rheumatic heart disease

Rheumatic fever is a delayed sequel to throat infection by a group A streptococcus. More than one third of affected children develop carditis, followed many years later – especially in the case of recurrent rheumatic infections – by progressive and permanent valvular lesions, known as rheumatic heart disease. 2 Rheumatic heart disease is now largely restricted to developing countries and most of the reduction in its incidence in wealthy countries is attributable to better living conditions with consequent reductions in the transmission of group A streptococci. Nevertheless, with the decline in rheumatic fever in industrialized countries and the emphasis on diseases such as malaria and HIV in developing countries, there has been a parallel reduction in research into this still prevalent and important condition. 3 Rheumatic heart disease remains an obvious public health burden across the developing world causing more than 200 000 deaths a year. 4 An exaggerated immune response to specific bacterial epitopes in a susceptible host is thought to be the basis of the disease. 5 Rheumatic heart disease usually results from the cumulative damage from recurrent episodes of acute rheumatic fever. It has been reported that after a first episode of carditis, cardiac ausculta tion becomes unremarkable in one-third of children but even these children may progress to significant rheumatic valve disease in later life, as confirmed by echocardiography. 6 Thus early detection of “subclini cal” rheumatic valve disease is vital, as it presents an opportunity for case detection at a time when prophylactic penicillin – to prevent recurrent episodes – can prevent progression to important valve disease in young adult life. Early detection of rheumatic heart disease in school children is traditionally done by listening for murmurs by stethoscope, followed by echocardiographic confir mation only in suspected cases. Recently, we did systematic echocardiographic screening in schools in Cambodia and Mozambique, to assess whether early case detection could be improved by using portable ultrasound. 7 We achieved a case detection rate by echocardiography approximately 10-fold that achieved by clinical examination only. Such screening thus makes it possible to identify children at risk of developing severe rheumatic valve disease for whom secondary prevention with penicillin prophylaxis may be effective. Acute rheumatic fever episodes can be prevented by antibiotic treatment of group A streptococcal throat infections, a strategy known as primary prophy

Heart disease detection in school children: Evaluation of heart sound tape-recordings as a mass screening method

To evaluate the performance and cost of tape-recorded heart sounds in the detection of heart disease among school children, 99.6 per cent of 17,366 Denver parochial school children were screened by tape-recordings, by duplicate physician examinations, and by 8-lead electrocardiograms. Students suspected of heart disease by any of the screening methods or by history were re-examined by cardiologists. None of the screening methods was perfect. Of 87 cases of uncorrected heart disease, 83 per cent were detected by physician examinations, 45 per cent by tape-recorded heart sounds and 41 per cent by electrocardiogram; and 7 per cent were missed by all three methods. The tape-recorded heart sound method was particularly poor for detection of rheumatic heart disease, atrial septal defects, congenital semilunar valve disease, and coarctation of the aorta. These categories included 78 per cent of the uncorrected cases of heart disease identified. The total assignable cost of heart disease detection per individual screened was 81 cents for duplicate physician examinations, 68 cents for heart sound tape-recordings, and 83 cents for the electrocardiogram. However, costs per heart disease case detected were $193.48 for physician examination, $301.29 for heart sound tape-recordings and $396.77 for the electrocardiogram. Since the undetected cases remain a potential community problem and since lower sensitivity of screening method results in higher cost per case detected, it would seem that the cheapest screening method in the long run is that which is the most sensitive case detector. It was concluded that the tape-recorded heart sound screening method tested was not yet suitable for routine mass application. Its screening specificity is satisfactory, but its sensitivity is not yet high enough to provide an advantage over the physicians it is designed to replace in mass primary screening for pediatric heart disease. However, the tape-recording method is promising and deserves further development. Future evaluation studies should be scientifically designed and performed in suitable populations.