Abstract

Background Sudden arrhythmic death syndrome (SADS), defined as sudden cardiac death (SCD) with a morphologically normal heart, is an important cause of sudden death. Hypoperfusion due to cardiac arrest followed by successful cardiopulmonary resuscitation (CPR) may induce histologic changes that mimic pathologic conditions. Detailed characterisation of such features and whether they could confound SADS diagnosis are not described. Methods Retrospective observational study analysing all consecutive cases of sudden death prospectively referred to a UK national cardiac pathology centre between 2017-2021. Cases showing hypoperfusion features were identified after review of clinical information and examination by expert cardiac pathologists. Results Out of 2,568 SCD cases, 126 (4.9%) were identified with hypoperfusion changes. Macroscopically, the commonest finding was left ventricular focal or diffuse subendocardial haemorrhage (13.5%). Microscopically, haemorrhage and contraction band necrosis (n=50, 37.7%), subendocardial acute infarction (n=44, 34.1%), interstitial mixed inflammatory cell infiltrates (n=31, 24.9%), healing granulation tissue (n=9, 7.1%) and subendocardial fibrosis (n=1, 0.7%) were observed. These changes correlated to duration of survival following resuscitation. In a subcohort of 41 cases, autopsy pathologists misinterpreted such changes as ischaemic myocardial infarction (n=7; 17%), myocarditis (n=5; 12.1%), or other pathologies (n=2; 4.8%) in 14 SADS cases. Conclusion We provide a comprehensive characterisation of hypoperfusion-related changes in the heart following successful CPR with survival, which are time related. These features can lead to diagnostic confusion among pathologists but knowledge of history of resuscitation with survival should help with general and expert pathology assessment and improve SADS diagnostic yield, prompting genetic screening of decedents’ relatives.