Myocardial apoptosis and SIDS

• Myocardial apoptosis is no typical mechanism in SIDS.
• Detection rate of apoptotic cardiomyocytes in SIDS and controls is low.
• Myocardial apoptosis is independent from myocardial inflammation.
• No evidence for a myocarditis being the underlying cause for SIDS.

Apoptosis mediates cardiac damage in severe forms of myocarditis. In fatal myocarditis, large amounts of cardiomyocytes show apoptotic DNA fragmentation, while in human controls, few apoptotic cardiomyocytes are found. In the present study the frequency of apoptosis in 88 SIDS cases (category 1b according to the San Diego Classification) and 15 control cases was investigated. In every case myocardial samples from 8 standard locations were collected. Detection of apoptotic cardiomyocytes was performed by TUNEL method. Furthermore the myocardial tissue was stained with HE and immunohistochemical methods (LCA, CD68, CD45-R0). More than 90% of the slides did not contain apoptotic cardiomyocytes at all. The detection rate of apoptotic cardiomyocytes was almost equal in control group (26.7%) and SIDS group (23.86%). A quantification of apoptotic cardiomyocytes per mm2 revealed no significant difference between both groups either. Altogether there is no evidence for a higher rate of apoptosis in SIDS.