Nonischemic left ventricular scar and cardiac sudden death in the young.

Summary Nonischemic left ventricular scar (NLVS) is a pattern of myocardial injury characterized by midventricular and/or subepicardial gadolinium hyperenhancement 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 etiology at autopsy. We examined 281 consecutive cases of sudden death of subjects aged 1 to 35 years. NLVS was defined as a thin, gray 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 fibroadipose tissue. Right ventricular involvement was always present. Patchy lymphocytic infiltrates were frequent. Genetic and molecular analyses clarified the etiology of NLVS in a subset of cases. Electrocardiographic (ECG) recordings were available in more than half of subjects. The most frequent abnormality was the presence of low QRS voltages (