Multimodality imaging assessment of mitral annulus disjunction in consecutive patients

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background Mitral annulus disjunction (MAD) has been investigated through trans-thoracic-echocardiography (TTE) and cardiac magnetic resonance (CMR) in different study cohorts and has been assumed either to represent a structural risk marker of sudden cardiac death or a benign, incidental finding. The imaging modality used to assess MAD might impact its prevalence and clinical significance. Purpose To assess the prevalence of MAD in consecutive patients undergoing TTE and CMR. Methods We retrospectively searched for MAD in consecutive patients undergoing TTE and CMR within six months, one from each other, at our center from March 2021 to April 2022. MAD was assessed in standard echocardiographic and CMR long-axis views and was defined as a ≥ 2 mm displacement between the left atrial wall-mitral valve leaflet junction hinge and the top of the left ventricular wall. Cases of pseudo-MAD and true-MAD were defined by MAD presence, respectively, during only systole and both systole and diastole. Results 124 patients (47 women; mean age: 59 years ± 17) were included. According to CMR, 38 patients (31%) presented with a structurally normal heart, and 37 (30%) presented with MAD. Patients with MAD presented more frequently MVP (27% vs. 1%; P<0.001), whereas patients without MAD were more frequently affected by non-ischemic cardiomyopathy (30% vs. 11%; p = 0.02). The two groups did not differ in age, sex, cardiac risk factors, symptoms, left ventricular volumes, ejection-fraction, pre-contrast T1- and T2-mapping, mitral annulus dimension and mitral regurgitation. MAD prevalence was higher by CMR than by TTE (30% vs. 8%; P=0.028). There was a low inter-modality agreement for the detection of MAD presence (Cohen's kappa=0.34) and a moderate agreement for MAD extent (ICC=0.71; 95% LOA 0.59, 0.8, p<0.05). Median MAD extent reported CMR and TTE were 2.6 mm (IQR 2.05–3.75 mm) and 4 mm (IQR 2.65–4.65 mm) respectively. All patients showing MAD at TTE demonstrated it at CMR too. Cases of true-MAD were observed at CMR (14% of the total cohort) but not at TTE. Conclusion In this cohort of consecutive patients, MAD was missed by TTE in more than 2 out of 3 patients exhibiting it at CMR. The high prevalence of MAD at CMR and the absence of significant association between this phenomenon and morpho-functional or structural alterations argue in favor of a benign finding at CMR. TTE detected MADs with higher extents compared to CMR. Further longitudinal studies are needed to evaluate the imaging-modality-related clinical relevance of MAD to improve patients’ risk stratification.