Myofiberbreak-up: A marker of ventricular fibrillation in sudden cardiac death

Background Electrophysiologically, ventricular fibrillation is defined as a “chaotic, random, asynchronous electrical activity of the ventricles due to repetitive re-entrant excitation and/or rapid focal discharge”. To this point its morphological equivalent has not been defined. Material and method Several groups of different diseases and types of accidental death in normal subjects were studied. A complete autopsy was performed and the hearts were examined in 432 cases. A total of 16 myocardial samples per heart were processed for histological examination and sections were stained by haematoxylin and eosin or by specific stains. The frequency, location and extent of myocellular segmentation (stretching and/or rupture) of intercalated discs and associated changes of myocardial bundles and single myocells were investigated. A quantitative analysis was performed and the data were processed for statistical evaluation. Results The frequency of MFB was maximal in coronary (88%) and Chagas (76%) groups followed by the intracranial brain haemorrhage group (52%). The extent of myofiberbreak-up was maximal in coronary/Chagas groups followed by intracranial haemorrhage and transplant groups. Conclusions No correlation was seen between gender, age, heart weight, degree of coronary atherosclerosis, myocardial fibrosis, survival and MFB. If our postulate is correct, finding MFB in the myocardium might allow the diagnosis of a malignant arrhythmia followed by cardiac arrest due to ventricular fibrillation even in the absence of clinical information (sudden death out-of-hospital).