P697Tissue doppler imaging alone is not reliable enough to identify hypertrophic cardiomyopathy mutation carriers


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Abstract

Background: Previous studies suggested that tissue Doppler imaging (TDI) was able to identify mutation carriers in familial hypertrophic cardiomyopathy (HCM), before the development of hypertrophy. However, data are limited. We performed a systematic analysis of conventional echocardiography, TDI and NT-proBNP in familial HCM to identify parameters that could identify mutation carriers.Methods and results: We analyzed 94 individuals divided in three groups: 1. HCM group (n=51); 2.Mutation carriers (n=24) – first-degree relatives with positive genotype and negative phenotype; 3. Controls (n=19) – first-degree relatives with negative genotype and phenotype. We performed conventional echocardiography and TDI in all individuals, including a TDI-derived index [Global Function Index (GFI) defined by (E:E'):S'], never studied in carriers. Additionally, we compared NT-proBNP plasma levels in the 3 groups. For comparison multiple linear regression age-adjusted was applied. Carriers and controls were similar in all echo parameters (MM, 2D and TDI, including GFI) and NT-proBNP plasma levels (normal values and p NS for all comparisons). Compared to HCM group, carriers had higher E' velocities (p<0.001), lower E/E' (septal: p=0.007; lateral: p NS; inferior: p<0.005; anterior: p=0.05) and lower GFI (septal: p=0.02; lateral: p=0.05; inferior: p=0.001; anterior: p NS), which correlated with NT-proBNP (septal: p<0.001; lateral: p=0.02). HCM group had very high levels of NT-proBNP (844.6±1143.9 ng/mL), which also correlated with GFI (lateral: p=0.02; septal: p< 0.0001). A' and S' were similar in the three groups.Conclusion: TDI parameters, including GFI, and NT-proBNP were normal in HCM mutation carriers and therefore are not reliable enough alone to make a preclinical diagnosis in HCM.Patients with phenotypic disease had lower early diastolic myocardial velocities, higher GFI but normal peak systolic myocardial velocities, suggesting that GFI in this population identifies diastolic dysfunction, which correlates with NT-proBNP.

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