Comparison of mitral valve apparatus anomalies between sarcomeric hypertrophic cardiomyopathy and Fabry disease cardiomyopathy

Abstract Background Despite different etiopathogenesis, Fabry disease (FD) cardiomyopathy and sarcomeric hypertrophic cardiomyopathy (HCM) share a similar hypertrophic phenotype. Cardiac magnetic resonance (CMR) plays a pivotal role in distinguishing between these two clinical conditions, thanks to the thorough morphological definition of the phenotype and non-invasive tissue characterization. A high prevalence of mitral apparatus anomalies has been previously described both in sarcomeric HCM and FD cardiomyopathy. Purpose This study systematically compares the morphology of the mitral apparatus in sarcomeric HCM and FD cardiomyopathy, to add new insights into differential diagnosis. Methods CMR images of 120 patients were retrospectively analyzed and divided as follows: healthy controls CTRL (n=40), HCM (n=40), and FD (n=40) with left ventricular hypertrophy (LVH). The analyses included the measurement of I) papillary muscles’ hypertrophy, expressed as the maximum diameter (D max) of the anterolateral (AL) and posteromedial (PM) papillary muscles (see Figure 1 A and B); II) the anteriorization of the anterolateral papillary muscle defined as the distance between the anterolateral papillary muscle and the anterior interventricular junction (Anteriorization of AL) (Fig. 1 C); III) the length of the anterior mitral leaflet (MVL length) (Fig. 1 D). All measurements were performed on cine-SSFP sequences in diastole. Results Compared to healthy controls, HCM and FD patients showed significant hypertrophy of both papillary muscles (p<0.001) and elongation of the anterior mitral leaflet (p<0.001). Both papillary muscles in FD patients showed greater hypertrophy compared to HCM patients (D max AL p=0.017 and D max PM p=0.039). No significant differences were observed between FD and HCM regarding MVL length (p=0.078). Compared to FD (p=0.028) and healthy controls (p<0.001), HCM patients showed greater anteriorization of the anterolateral papillary muscle. (Results are summarized in Table 1). Conclusions From the comparison of mitral valve apparatus anomalies between HCM and FD, it emerged that patients with FD cardiomyopathy show a higher degree of papillary muscle hypertrophy, while patients with sarcomeric HCM display a greater anterior displacement of the anterolateral papillary muscle. The systematic analysis of the morphology of mitral apparatus can be integrated in the differential diagnosis between these two pathologies.Fig.1 Representation of MeasurementsTable 1.Summary results table