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Background Lamin A/C cardiomyopathy (CM) is an inherited disease due to LMNA gene mutation with particular phenotype that associates conduction disorders, frequent atrial fibrillation and life-threatening ventricular arrhythmias, with normal or altered ventricular systolic function. Cardiac magnetic resonance (CMR) studies suggest frequent late gadolinium enhancement (LGE) involving septal mid-myocardium. Aims To assess the added value of CMR to conventional clinical features of Lamin A/C CM for the prediction of a positive LMNA gene testing. Methods We performed a retrospective monocentric study in all index patients referred for genetic testing for a clinical suspicion of Lamin A/C CM. Clinical, ECG and imaging data including CMR at time of genetic testing in patients with a positive test (LMNA+) and patients without (LMNA-) were compared. The diagnostic performances of relevant parameters for the prediction of a positive LMNA gene testing were analyzed in several logistic regression models. Results 90 patients were included (55 LMNA+, 35 LMNA-).49% had significant left ventricular (LV) dilatation on echocardiography,57% had a LV ejection fraction (LVEF)<50%, 46% had a significant left atrial dilatation, and 17% had right ventricular dysfunction. None of these parameters were different comparing LMNA+ and LMNA- patients. LMNA+ patients had significantly more frequent familial history of sudden cardiac death (SCD) or CM. There were no significant differences between LMNA+ and LMNA- patients in terms of conduction disorders, ventricular and supra-ventricular arrhythmias. The only significant difference on ECG was a more frequent abnormal R-wave progression in V1-V3 in LMNA+ patients (87.8% vs 39.4%, p<0.001). 55 patients had a CMR (28/55 LMNA+, 27/35 LMNA-). The main reason for not performing CMR was the presence of cardiac implantable electronic device. LMNA+ patients had significantly more LGE than LMNA- (20/28 (71%) vs 9/27 (33%), p=0.011). The main differences in LGE features between the 2 groups were septal involvement (70% in LMNA+ vs 11% in LMNA-, p=0.005) and mid-myocardium localization (95% vs 44%, p=0.005). In a first logistic regression model without CMR data in all 90 patients, V1-V3 R-wave abnormalities, familial history of SCD and sinus node dysfunction were independent predictors of a positive LMNA gene testing (Sensitivity 89%, specificity 46%, accuracy 72%). A second model in the 55 patients who had a CMR showed better accuracy (85%), mainly driven by increased specificity (81%) with preserved sensitivity (89%). V1-V3 R-wave abnormalities, premature ventricular contractions, non-depressed LVEF and septal LGE predicted positive LMNA gene testing in this model (Septal LGE OR=31, 95% CI 4–715; p=0.005). Conclusion CMR, particularly septal mid-myocardium LGE, carries good diagnostic accuracy to predict a positive LMNA gene testing in clinically suspected Lamin A/C CM with increased specificity when added to conventional red flags. Funding Acknowledgement Type of funding source: None

Background Mitral valve prolapse (MVP) is a frequent disease that can be complicated by mitral regurgitation (MR), heart failure, arterial embolism, rhythm disorders and death. Purpose We sought to evaluate the correlates of late gadolinium enhancement (LGE), and the prognostic significance of ventricular size, function, and LGE by cardiac magnetic resonance (CMR) imaging on cardiovascular morbi-mortality in patients with MVP Methods We included 426 patients (54±15 years, 57% male) with MVP (trace to severe MR) between 2010 and 2019 who underwent a comprehensive echocardiography and CMR imaging. Gadolinium was injected in 411 (96%) patients. The main outcome endpoint was a composite endpoint of cardiovascular death, heart failure, new onset atrial fibrillation or arterial embolism, censored at the time of mitral valve intervention. Results Among the 411 patients, LGE+ was found in 118 (29%; 100 myocardial wall including 78 basal inferolateral midwall, 30 papillary muscles) and was more frequent with worse MR volume and LV remodeling. Correlates of LGE in multivariable analysis were LV mass index (OR 1.02, P=0.008), moderate-severe MR (OR 2.15, P=0.017) and coronary artery disease (OR 5.8, P=0.013). At 4 years, survival without cardiovascular events was decreased in patients with LGE+ (50.0±11.9 vs 73.5±6.3%, p<0.0001). In a stepwise multivariable analysis including classical predictors of outcome, grade of MR, LA volume index and the presence of LGE on CMR imaging (HR: 2.15 [1.15–4.02], P=0.017) were associated with impaired event-free survival. Conclusion CMR imaging provides additional information to echocardiography in the clinical work-up of MVP. Localized LV myocardial fibrosis is a predictor of cardiovascular event in MVP patients. Funding Acknowledgement Type of funding source: Public Institution(s). Main funding source(s): DGOS (PHRCI), Fondation Cœur et Recherche