Aims: To quantify the variation in fibrosis, fat and muscle within the walls of both ventricles and within the different regions of the heart from six patients dying suddenly of arrhythmogenic right ventricular dysplasia (ARVD) aged 20-60 years.
Methods: Seven heart regions were examined both macroscopically and histologically using the Picro-Sirius red stain. Quantification of fibrosis, fat and muscle was performed in each region and transmural layer using grid counting.
Results: There were macroscopic changes in all examined hearts. A higher percentage of fat with less fibrosis and muscle was observed within the right ventricle of the older patients. The left ventricle had more pathology in the older age group. Statistical differences in pathology in the heart were found. Fat predominated in the epicardial layer in the right and left ventricles of all patients, while the interventricular septum was the least affected.
Conclusions: In ARVD, the pathology varies with age in both ventricles, fibrosis being the earliest hallmark of disease, with fatty infiltration evolving later. It should be labelled arrhythmogenic ventricular dysplasia because of biventricular involvement. Histopathologists should therefore sample from whole slices of the heart, so that all the changes can be observed.