Arrhythmogenic right ventricular cardiomyopathy with left ventricular involvement: histopathology and MRI features

Objective: The aim of the present investigation was to confirm histopathology and MR features of arrhythmogenic right ventricular cardiomyopathy (ARVC), particularly with the left ventricular involvement. Methods: Nine patients (4 male, 5 female; 13 to 54 years old, mean age 40.44 ± 15.99), with a pathologic diagnosis of ARVC at heart transplantation, were included, of which 7 patients were scanned for MR imaging before transplantation. Results: Severe dilation of right ventricular (RV) cavity and left ventricular one (LV) were observed in 7 and 8 hearts, respectively. All hearts showed severe and transmural RV muscle loss, where RV wall was almost completely filled with either fatty tissue (3 cases) or fibrofatty tissue (6 cases). LV involvement was diagnosed histologically in all cases. Both the septum and the LV free wall were affected in 2 cases; 7 cases disclosed selective free wall involvement. LV fatty or fibrofatty substitution was predominantly located in the subepicardial and mediomural wall layers in 5 hearts. a diffuse interstitial fibrosis with patchy infiltration was noted in the other 4 hearts. 7 patients underwent MR scanning. MR scanning demonstrated global RV severe dilation and thinning in 5 cases, of which linear fatty infiltration was found in 3 cases. RV presented wall thickness preservation and normal cavity in the remaining 2 cases, in which left involvement existed. LV was dilated in all cases (mildly in 3, moderately in 2, severely in 2). The LV ejection fraction was (21.66 ± 7.05)%, and subepicardial fatty infiltration was found in 2 patients, selectively involving posterolateral wall. 4 patients showed the LV wall thinning diffusely in free wall, and the other 3 mainly involved septum, apex and posterolateral wall, respectively. All 5 patients with delayed enhancement showed varying degrees of hyperenhancement, mainly involving the posterolateral wall (transmural in 2 and epicardial in 2), septum ( mediomural in 2) and apex in 2 (focal or transmural). Additionally, transmural hyperenhancement was also found in the RV wall, involving free wall in 2, RV apex in 1 and posterior wall in 1 case, respectively. Conclusions: ARVC with reference to left ventricular involvement had severe cardiomegaly and heart failure. MRI can partially reveal tissue characteristics, including fatty infiltration and fibrosis, as well as morphologic features. (authors)