Table 2.

Pitfalls for the differential diagnosis of IHD and AC as the cause of death in postmortem of SCD victims. Put together by the authors, partially based upon refs. [5,6,12–14].

Cardiac condition	IHD	AC
LV fibrosis	Scars represent the sequelae of previous myocardial infarction. Replacement fibrosis at the scars usually involving the ventricular wall from subendocardium to the subepicardium (can be transmural). The scar coincides with an anatomical coronary distribution (sometimes several territories can be simultaneously affected).	Replacement with or without interstitial fibrosis involving the ventricular wall from subepicardium to the subendocardium (can be only midmyocardial or transmural). The scar typically affects the inferolateral wall, and sometimes extends to adjacent walls being occasionally completely circumferential.
LV fatty infiltration	Fatty infiltration is possible at the myocardial scars of old myocardial infarctions.	Fatty infiltration associates fibrosis and very often degenerated myocytes exhibit cytoplasmic lipid droplets.
Other features at the myocardium	Infrequently histological signs of acute or subacute myocardial infarction are identified when the ischemic insult precedes more than 4 h the development of the lethal ventricular arrhythmia causing the death (intramyocardial oedema, haemorrhage and neutrophilic infiltrates). RV is often preserved. Hypertensive heart disease with myocardial remodelling and intramyocardial small vessel disease are frequent.	Lymphocyte infiltrates (ranging from scarce to definite myocarditis) can be present.
Non-myocardial features	Atherosclerotic plaques are often identified, not always causing significant stenosis (>75%). Infrequently complicated plaques (eroded, ruptured, with or without thrombus) are identified. More frequent over 35 years and typically men with metabolic syndrome features (e.g. non-alcoholic fatty liver disease). Familial aggregation may be present.	In rare forms (autosomal recessive) woolly curly hair and keratosis palmoplantaris are extracardiac hallmarks of the disease. Wide variety of ages ranging from adolescents to middle aged, more men than women and often sports-triggered deaths. Familial aggregation is often present.

IHD: ischemic heart disease; AC: arrhythmogenic cardiomyopathy; SCD: sudden cardiac death; LV: left ventricular; RV: right ventricular.