This focused review presents a critical appraisal of the World Heart Federation criteria for the echocardiographic diagnosis of rheumatic heart disease (RHD) and its performance in African RHD screening programmes. It identifies various logistical and methodological problems that negatively influence the current guideline’s performance. The authors explore novel RHD screening methodology that could address some of these shortcomings and if proven to be of merit, would require a paradigm shift in the approach to the echocardiographic diagnosis of subclinical RHD.
ObjectiveThe World Heart Federation (WHF) criteria incorporate a Doppler-based system to differentiate between ‘physiological’ and ‘pathological’ mitral regurgitation (MR)—a sole criterion sufficient for the diagnosis of WHF ‘borderline’ rheumatic heart disease (RHD). We have identified that interscallop separations (ISS) of the posterior mitral valve (MV) leaflet, can give rise to pathological MR in an otherwise-normal MV. We aimed to establish and compare the prevalence of ISS-related MR among South African children at high and low risk for RHD.MethodsA prospective cross-sectional echocardiographic study of 759 school children (aged 13–18) was performed. Cases with MR≥1.5 cm underwent a second comprehensive study to determine the prevalence of RHD according to the WHF guideline and establish the underlying mechanism of MR.ResultsOf 400 high-risk children, two met criteria for ‘definite RHD’ (5 per 1000 (95% CI 1.4 to 18.0); p=0.5) and 11 for ‘borderline RHD’ (27.5 per 1000 (95% CI 15.4 to 48.6)). Of 359 low-risk children, 14 met criteria for borderline RHD (39 per 1000 (95% CI 23.4 to 64.4)). Comprehensive echocardiography identified an underlying ISS as the mechanism of isolated pathological MR in 10 (83.3%) high-risk children and 11 low-risk children (78.5%; p>0.99).ConclusionsISS are a ubiquitous finding among South African schoolchildren from all risk profiles and are regularly identified as the underlying mechanism of WHF pathological MR in borderline RHD cases. A detailed MV assessment with an emphasis on ascertaining the underlying mechanism of dysfunction could reduce the reported numbers of screened cases misclassified as borderline RHD.
Introduction:The World Heart Federation (WHF) screening criteria do not incorporate a strict, reproducible definition of anterior mitral valve leaflet (AMVL) restriction.Using a novel definition, we have identified two distinct AMVL restriction configurations. The first, called "distal tip" AMVL restriction is associated with additional morphological features of rheumatic heart disease (RHD), while the second, "gradual bowing" AMVL restriction is not. This "arch-like" leaflet configuration involves the base to tip of the medial MV in isolation. We hypothesize that this configuration is a normal variant. Methodology:The prevalence and associated leaflet configurations of AMVL restriction were assessed in schoolchildren with an established "very low" (VLP), "high" (HP), and "very high" prevalence (VHP) of RHD.Results: 936 studies were evaluated (HP 577 cases; VLP 359 cases). Sixty-five cases of "gradual bowing" AMVL restriction were identified in the HP cohort (11.3%, 95% CI 8.9-14.1) and 35 cases (9.7%, 95% CI 7-13.2) in the VLP cohort (P = .47). In the second analyses, an enriched cohort of 43 studies with proven definite RHD were evaluated. "Distal tip" AMVL restriction was identified in all 43 VHP cases (100%) and affected the central portion of the AMVL in all cases. Conclusion:"Gradual bowing" AMVL restriction appears to be a normal, benign variant of the MV, not associated with RHD risk nor with any other morphological features of RHD. Conversely, "Distal tip" AMVL restriction was present in all cases in the VHP cohort with no cases exhibiting a straight, nonrestricted central portion of the AMVL. This novel finding requires further investigation as a potential RHD rule-out test of the MV.
Introduction The World Heart Federation (WHF) criteria identify a large borderline rheumatic heart disease (RHD) category that has hampered the implementation of population-based screening. Inter-scallop separations (ISS) of the posterior mitral valve leaflet (PMVL), a recently described normal variant of the mitral valve, appears to be an important cause of mild mitral regurgitation (MR) leading to misclassification of cases as WHF ‘borderline RHD’. This study aims to report the findings of the Echo in Africa project (EIA), a large-scale RHD screening project in South Africa and determine what proportion of borderline cases would be re-classified as normal if there were a systematic identification of ISS-related MR. Methods A prospective cross-sectional study of underserved secondary schools in the Western Cape was conducted. Participants underwent a screening study with a handheld (HH) ultrasound device. Children with an abnormal HH study were re-evaluated with a portable laptop echocardiography machine. A mechanistic evaluation was applied in cases with isolated WHF ‘pathological’ MR (WHF ‘borderline RHD’). Results 5255 participants (mean age 15± years) were screened. 3439 (65.8%) were female. 49 cases of WHF ‘definite RHD’ (9.1 cases/1000 [95% CI, 6.8-12.1 cases/1000]) and 104 cases of WHF ‘borderline RHD’ (19.5 cases/1000[95% CI,16.0-23.7 cases/1000]) were identified. ISS-related MR was the underlying mechanism of MR in 48/68 cases classified as WHF ‘borderline RHD’ with isolated WHF ‘pathological’ MR (70.5%). Conclusion In a real-world, large-scale screening project, the adoption of a mechanistic evaluation based on the systematic identification of ISS-related MR markedly reduced the number of WHF ‘screen-positive’ cases misclassified as WHF ‘borderline RHD’. Implementing strategies that reduce this misclassification could reduce the cost- and labour-burden on large scale RHD screening programs.
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