The role of focal myocardial inflammation in sudden unexpected cardiac and noncardiac deaths—A clinicopathological study

The significance of focal myocardial inflammation in sudden death is poorly understood, because there are few studies addressing its frequency in noncardiac and cardiac arrhythmic deaths. We prospectively assessed inflammation in 384 consecutive hearts seen in consultation from a single medical examiners' office. Hearts were received intact and sectioned uniformly in five areas and reviewed histologically by a single pathologist. Intrinsic inflammatory diseases of the myocardium were excluded. Infiltrates were classified as lymphocytic without necrosis, lymphocytic with myocyte necrosis, and eosinophilic. Histologic findings were retrospectively correlated with other cardiac findings, history of drug and medication use, postmortem toxicology, and cause of death. In the 384 hearts, any infiltrate was found in 18%. There were multifocal infiltrates in 9%, inflammation with necrosis in 2%, and eosinophilic myocarditis in 4%. Infiltrates were most frequent in natural noncardiac deaths (31%), and least frequent in traumatic deaths (12%). Infiltrates with myocyte necrosis occurred in 4% of arrhythmic deaths with no other cause, 3% of cardiac deaths with cardiomegaly, 3% of traumatic deaths, 2% of natural noncardiac deaths, 2% of other cardiac deaths, and 1% of coronary deaths. Infiltrates were common in patients on antibiotics (54%) or neuroleptic drugs (27%). Eosinophilic infiltrates were especially common in patients on antibiotics (18%). We conclude that incidental cardiac inflammatory infiltrates without necrosis are not uncommon, but focal myocarditis, defined as inflammation with necrosis, occurs in about 5% of hearts, and may be considered a possible contributory factor. Incidental infiltrates are common in patients on medications, especially antibiotics.