Key result
Interscallop separations were identified as the underlying mechanism of isolated pathological MR in 83.3% of high-risk and 78.5% of low-risk children with borderline RHD (p>0.99).
Why the study?
Interscallop separations of the posterior mitral valve leaflet can cause pathological MR in an otherwise-normal valve, creating potential overlap with WHF borderline RHD criteria.
Does interscallop separation of the posterior mitral valve leaflet explain pathological mitral regurgitation in children screened for rheumatic heart disease?
Cross-Sectional (n=759)
Does interscallop separation of the posterior mitral valve leaflet explain pathological mitral regurgitation in children screened for rheumatic heart disease?
Absolute Event Rate: 83.3% vs 78.5%
p-value: p=>0.99
Interscallop separations of the posterior mitral valve leaflet are a common cause of mitral regurgitation that may be misclassified as borderline rheumatic heart disease by WHF criteria.
Interscallop separations may explain isolated pathological MR misclassified as borderline RHD; leaves open whether criteria require prospective revision.
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.
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Hunter et al. (2020) conducted a cross-sectional in Rheumatic heart disease (n=759). High risk for RHD vs. Low risk for RHD was evaluated on Interscallop separations (ISS) as the mechanism of isolated pathological MR (p=>0.99). Interscallop separations were identified as the underlying mechanism of isolated pathological MR in 83.3% of high-risk and 78.5% of low-risk children with borderline RHD (p>0.99).
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