Spatial QRS-T angle can indicate presence of myocardial fibrosis in pediatric and young adult patients with hypertrophic cardiomyopathy

Myocardial fibrosis, expressed as late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (CMR), is an important risk factor for malignant cardiac events in hypertrophic cardiomyopathy (HCM). However, CMR is not easily available, expensive, also needing intravenous access and contrast. To determine if derived vectorcardiographic spatial QRS-T angles, an aspect of advanced ECG (A-ECG), can indicate LGE to appropriately prioritize young HCM-patients for CMR. Young patients (age 7–31 years) with clinical HCM ( N  = 19) or genotype-positive but phenotype-negative (G+ P-) results ( N  = 6) and nine healthy volunteers were evaluated for LGE by CMR at a single centre between 2011 and 2018. A-ECG was performed within 4 months before and 6 months after CMR and evaluated for spatial mean and peaks QRS-T angles. ECG Risk-score and frontal, two-dimensional QRS-T angle were also calculated from the 12‑lead ECG. All QRS-T angles were significantly higher in the HCM group with LGE as compared to the HCM group without LGE, and the G+ P- and Healthy groups. Only HCM-patients showed LGE (11/19). The optimal cut-offs for indicating LGE were > 50° for the spatial peaks (AUC = 0.98 [95 %CI 0.95–1.00], sensitivity 100 %, specificity 93 %; p  < 0.001), >80° for the spatial mean (AUC = 0.91; p  < 0.001), and > 60° for the frontal QRS-T angles (AUC = 0.85; p  < 0.001), and > 2 points for an established ECG risk-score (AUC = 0.90, p  < 0.001). A spatial peaks QRS-T angle >50° has excellent sensitivity and specificity as a marker of myocardial fibrosis in a young patients with HCM, and can be useful for management and follow-up of such patients.