Utility of the Frontal-Plane QRS-T Angle in a Real-World Screening Population, for Identification of Hypertrophic Cardiomyopathy.

The frontal QRS-T angle, derived from a standard 12-lead electrocardiogram (ECG), quantifies the relationship between ventricular depolarization and repolarization. Although a widened angle has been associated with myocardial disarray and arrhythmic risk, its diagnostic utility for detecting hypertrophic cardiomyopathy (HCM) in children, adolescents, and young adults has not been well established. We analyzed 6,128 participants aged ≤ 30 years from the Heartfelt community cardiovascular screening program. HCM was defined as septal or posterior wall thickness ≥ 2.5 SD above the mean for body-surface area in pediatric participants or ≥ 15 mm in adults. In a secondary analysis, the ≥ 15 mm threshold was applied irrespective of age. Electrocardiographic variables were evaluated using logistic regression and receiver operating characteristic (ROC) analyses. Among the 6,128 screened participants, 162 met criteria for HCM. Compared with unaffected individuals, participants with HCM were younger and had shorter PR intervals, QRS durations, and QTc values (all p < 0.001). The frontal QRS-T angle did not differ significantly between groups (23° [12-34] vs 24° [14-36]; p = 0.175) and demonstrated poor discriminatory performance (AUC 0.47; 95% CI 0.43-0.51). Findings were similar in the secondary analysis applying the ≥ 15 mm threshold across all ages (AUC 0.43; p = 0.67). In this large cohort of young community-screened participants, the frontal QRS-T angle did not distinguish individuals with hypertrophic cardiomyopathy. These findings suggest that adult-derived electrocardiographic thresholds may not be directly applicable to pediatric or athletic populations and highlight the need for age-specific ECG screening criteria.