Nonischemic left ventricular scar and cardiac sudden death in the young

Nonischemic Left Ventricular Scar (NLVS) is a pattern of myocardial injury characterized by midventricular and/or subepicardial gadolinium hyper enhancement at cardiac magnetic resonance, in absence of significant coronary artery disease. We aimed to evaluate the prevalence of NLVS in juvenile sudden cardiac death and to ascertain its aetiology at autopsy. We examined 281 consecutive cases of sudden death of subjects aged 1 to 35 years of age. NLVS was defined as a thin, grey rim of subepicardial and/or midmyocardial scar in the left ventricular free wall and/or the septum, in absence of significant stenosis of coronary arteries. NLVS was the most frequent finding (25%) in sudden deaths occurring during sports. Myocardial scar was localized most frequently within the left ventricular posterior wall, and affected the subepicardial myocardium, often extending to the midventricular layer. On histology it consisted of fibrous or fibro-adipose tissue. Right ventricular involvement was always present. Patchy lymphocytic infiltrates were frequent. Genetic and molecular analyses clarified the aetiology of NLVS in a subset of cases. ECG recordings were available in over half of subjects. The most frequent abnormality was the presence of low QRS voltages (< 0,5 mV) in limb leads. In serial ECG tracings, the decrease in QRS voltages appeared, in some way progressive. NLVS is the most frequent morphologic substrate of juvenile cardiac sudden death in sports. It can be suspected based on ECG findings. Autopsy study and clinical screening of family members are required to differentiate between Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia and chronic acquired myocarditis.