Morpho-mechanistic screening criteria for the echocardiographic detection of rheumatic heart disease.

INTRODUCTION: Screening echocardiography, guided by the current World Heart Federation (WHF) criteria, has important limitations that impede the establishment of large-scale rheumatic heart disease (RHD) control programmes in endemic regions. The criteria misclassify a significant number of normal cases as borderline RHD. Prior attempts to simplify them are limited by incorporation bias due to the lack of an externally validated, accurate diagnostic test for RHD. We set out to assess novel screening criteria designed to avoid incorporation bias and to compare this against the performance of the current WHF criteria. METHODS: The performance of the WHF and the morpho-mechanistic (MM) RHD screening criteria (a novel set of screening criteria that evaluate leaflet morphology, motion and mechanism of regurgitation) as well as a simplified RHD MM 'rule-out' test (based on identifying a predefined sign of anterior mitral valve leaflet restriction for the mitral valve and any aortic regurgitation for the aortic valve) were assessed in two contrasting cohorts: first, a low-risk RHD cohort consisting of children with a very low-risk RHD profile. and second, a composite reference standard (CRS) RHD-positive cohort that was created using a composite of two criteria to ensure a cohort with the highest possible likelihood of RHD. Subjects included in this group required (1) proven, prior acute rheumatic fever and (2) current evidence of predefined valvular regurgitation on echocardiography. RESULTS: In the low-risk RHD cohort (n=364), the screening specificities for detecting RHD of the MM and WHF criteria were 99.7% and 95.9%, respectively (p=0.0002). The MM rule-out test excluded 359/364 cases (98.6%). In the CRS RHD-positive cohort (n=65), the screening sensitivities for the detection of definite RHD by MM and WHF criteria were 92.4% and 89.2%, respectively (p=0.2231). The MM RHD rule-out test did not exclude any cases from the CRS RHD-positive cohort. CONCLUSION: Our proposed MM approach showed an equal sensitivity to the WHF criteria but with significantly improved specificity. The MM RHD rule-out test excluded RHD-negative cases while identifying all cases within the CRS RHD-positive cohort. This holds promise for the development of a two-step RHD screening algorithm to enable task shifting in RHD endemic regions.

The variable spectrum of anterior mitral valve leaflet restriction in rheumatic heart disease screening.

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.

Interscallop separations of the posterior mitral valve leaflet: a solution to the 'borderline RHD' conundrum?

OBJECTIVE: The 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. METHODS: A 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. RESULTS: Of 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). CONCLUSIONS: ISS 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.