Nonischemic left ventricular scar and cardiac sudden death in the young

Abstract

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 (<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.

Arrhythmogenic right ventricular cardiomyopathy: evaluation of the current diagnostic criteria and differential diagnosis

“…Rather than an ECG marker of advanced RV disease, low QRS voltages indicate LV involvement (regardless of the RV disease severity) and reflect loss of myocardium/electrical voltages of the LV wall and replacement by electrically inert fibrofatty scar tissue. [54][55][56][57][58] The ECG abnormalities resulting from delayed RV activation/conduction include RBBB (usually incomplete and rarely complete), QRS fragmentation, prolongation of right precordial QRS duration with a delayed S-wave upstroke, terminal activation duration (TAD) > _55 ms, and epsilon waves. The accuracy of the presence of epsilon waves as a diagnostic tool has been questioned since these discrete signals are related to ECG filtering and sampling rate, giving rise to large interobserver variability.…”

“…Distinctive ECG features of LV involvement in ARVC include T-wave inversion in the infero-lateral leads and low QRS voltages (<0.5 mV) in limb leads, which reflect the loss of myocardium and electrical voltages of the LV wall. 55,56 Ventricular tachycardia is characteristically monomorphic, with a RBBB morphology which denotes its origin form the LV. 8,60 The typical LV imaging phenotype is characterized by a ventricular remodelling pattern consisting of mild LV dysfunction and no or mild LV dilatation, in association with a significant amount of subepicardial/mid-myocardial (non-ischaemic) LGE affecting multiple LV segments (mostly the inferolateral wall regions) ( Figure 2).…”

Screening young athletes for diseases at risk of sudden cardiac death: role of stress testing for ventricular arrhythmias

“…During the 5-year study period, 10,985 non-professional competitive athletes (66% males, median age 15 [13][14][15][16][17][18] years, 97% White) underwent PPE. Of those, 451 (4.1%, 95% CI 3.7%-4.5%) showed positive medical history, pathological physical examination or abnormal baseline ECG.…”

“…[17][18][19][20][21][22][23] Previous outcome studies provided evidence that the non-ischaemic LV scar may be associated with lifethreatening VA and SCD. [17][18][19][20] In particular, we found in a previous investigation that, during a mean 3-year follow-up, 22% of athletes with non-ischaemic LV scars and VA experienced ICD shock, sustained ventricular tachycardia or SCD; in 5 of 6 cases the event occurred during exercise. 17 In the present study, none of the athletes who received a diagnosis of non-ischaemic LV scar experienced malignant events during follow-up.…”

“…Although isolated LV LGE with subepicardial/midmyocardial distribution is traditionally interpreted as the consequence of a previous myocarditis, there is increasing evidence that it may also reflect a left-dominant arrhythmogenic cardiomyopathy, characterised by fibrofatty myocardial replacement of the LV and VA with a RBBB morphology. 17,18,24 In this regard, we previously reported the case of a 39 year-old cyclist with CMR evidence of isolated non-ischaemic LV scar and complex VA at exercise testing. 17 The athlete, who was managed by a different sports medicine centre, was considered eligible to compete because the finding of LGE on CMR was interpreted as a sign of a healed (and benign) inflammatory process, although he did not have a clinical history of acute myocarditis.…”