Sudden unexpected cardiac deaths among young Swedish orienteers - Morphological changes in hearts and other organs

During the years 1979-1992 an accumulation of sudden unexpected cardiac dea ths (SUD) occurred among young Swedish orienteers. A reevaluation of materi al saved from 16 autopsies was undertaken. Myocarditis was most frequent. I t was found in different stages in the majority of cases, indicating subacu te or chronic disease with ongoing reparative processes. There were severe morphological changes in all cases. All but one showed a picture of fibrosi s and unspecific hypertrophy and/or degenerative changes in myocytes. The h earts were classified into three groups (A-C), based on the morphological p icture of the retrieved heart tissue and the macroscopic description. Group A comprised five cases in which areas with active myocarditis combined wit h areas of healing or healed myocarditis widely distributed in the left ven tricle were the only morphological changes found. Group B comprised four ca ses demonstrating foci of myocarditis in different stages in the left ventr icle and changes resembling those found in arrhythmogenic right ventricular dysplasia (ARVD), including degenerative changes with fibrosis and fatty i nfiltration located in either ventricle. Group C comprised the remaining se ven cases. In none of the cases were coronary artery or valvular anomalies present, nor significant coronary sclerosis or changes outside the heart th at could cause SUD.