AN INCREASE IN SUDDEN UNEXPECTED CARDIAC DEATHS AMONG YOUNG SWEDISH ORIENTEERS DURING 1979-1992

Background Sixteen cases of sudden unexpected cardiac death, 15 males and one female, are known to have occurred among young Swedish oriente ers from 1979 to 1992, of which seven cases occurred between 1989 and 1992. This is considered to be indicative or an increased death Result s Histopathological evaluation showed myocarditis in a higher than exp ected proportion of cases. In one such case, which we studied before t he sudden unexpected death occurred, the victim had suffered a Chlamyd ia pneumoniae infection verified by serology, and a nucleotide sequenc e was found in the heart and lung by means of the polymerase chain rea ction (PCR) that hybridized with a probe specific for that organism. M ale Swedish orienteers do not, however, seem to have an increased rate of exposure to this agent. No further sudden unexpected deaths among young orienteers have occurred over the past 3.5 years. At the beginni ng of that period, attempts were made to modify training habits and at titudes.