Autoptic findings of sudden cardiac death (SCD) in patients with arrhythmogenic ventricular cardiomiopathy (AVC) from left ventricle and biventricular involvement

Abstract

Objectives: To evaluate autoptic histopathological findings of arrhythmogenic ventricular cardiomyopathy (AVC) as major cause of sudden cardiac death (SCD) in young adults.

Background: According to Heart Rhythm Society (HRS)'s international consensus, histological criteria for AVC diagnosis include a progressive myocardial atrophy of the right ventricle characterized by a transmural fatty or fibrofatty replacement in a segmental or diffuse pattern (residual myocytes <60 % vs 60-75 % by morphometric analysis) explaining the electrical instability with increased risk of SCD. However, there is increasing evidence for atypical patterns of localizations and percentage of fibrofatty replacement suggesting the need to update histopathological features of AVC.

Methods: Histology examination of ventricles, atria, and septum was performed on 10 autopsy of SCD due to AVC. Staining with hematoxylin-eosin and PicroSirius Red/Fast Green were performed on the heart samples to identify specific fibrofatty patterns.

Results: Our analysis showed that: 1) myocardial replacement by a diffuse segmental fatty or fibro-fatty tissue characterized right and left ventricles as well as atrial walls; 2) the degree of fibrofatty tissue replacement was less than 40 % both in left ventricle (n = 4, 40 %) and biventricular (n = 6, 60 %) localization; 3) perivascular fibrosis, inflammatory infiltrate, areas of hypertrophy and/or areas of coagulative necrosis as signs of hypoxic damage in the first stage.

Conclusions: We confirmed prior evidence for fibrofatty replacement both in biventricular and septal localizations. Importantly, we observed a less degree (<40 %) of fibrofatty replacement as compared to current guidelines. This supports the need to further explore the histological patterns of fibrofatty infiltration in a larger study population to improve the histological diagnostic criteria of AVC.

Keywords: ARVC; AVC; Arrhythmogenic right ventricular cardiomyopathy; Arrhythmogenic ventricular cardiomyopathy; Autopsy study; Fibrofatty replacement; Histology criteria; Sudden cardiac death.