[Electrocardiographic prediction parameters for life-threatening arrhythmic events in congenital long QT syndrome...

Objective: To analyze the electrocardiogram (ECG) data of congenital long QT syndrome (LQTS) patients, and to identify the ECG parameters for prediction of life-threatening arrhythmic events (LAEs). Methods: This cohort study enrolled patients diagnosed with congenital LQTS at the Department of Cardiology, Beijing Tsinghua Changgung Hospital from September 2014 to May 2023. Baseline clinical and ECG data were collected. Patients were followed with LAEs as the primary endpoint. Based on the occurrence of LAEs, patients were divided into two groups: the event group and the event-free group. Cox regression analysis was used to identify independent predictors of LAEs in LQTS patients. Results: A total of 293 patients diagnosed with congenital LQTS were included, aged 32.5 (19.0, 41.8) years, including 201 females (68.6%). Sixty-six patients experienced LAEs and 227 patients did not. Compared to the event-free group, the event group had a younger onset age (13.0 (5.5, 20.5) years vs. 26.0 (13.0, 35.0) years), a slower heart rate (69.0 (59.5, 76.5) beats/min vs. 77.0 (67.0, 88.0) beats/min), a higher proportion with family history of sudden cardiac death (30.3% vs. 14.5%), as well as longer QT intervals (500.0 (467.0, 594.0) ms vs. 428.0 (402.0, 470.0) ms) and QTc intervals (544.0 (502.5, 589.0) ms vs. 489.0 (480.0, 504.0) ms). Additionally, the event group had higher peak T-wave alternans value (65.0 (42.5, 85.3) μV vs. 44.0 (36.0, 54.0) μV), a higher proportion of patients with documented torsades de pointes (TdP) or ventricular fibrillation (VF) on 24-hour Holter monitoring (39.3% vs. 4.9%), and higher rates of pharmacological treatment (100.0% vs. 9.7%) and device therapy or left cardiac sympathetic denervation (45.5% vs. 2.2%) (all P<0.05). Multivariate Cox regression analysis identified that the heart rate<60 beats/min (HR=2.0, 95%CI: 1.0-3.7) and QTc interval ≥500 ms (HR=2.9, 95%CI: 1.5-5.6) on 12-lead ECG, as well as peak T-wave alternans value ≥55.5 μV (HR=3.2, 95%CI: 1.3-7.8) and documented TdP or VF (HR=2.0, 95%CI: 1.1-3.7) on 24-hour Holter monitoring were independent predictors of LAEs in LQTS patients (all P<0.05). Conclusion: Heart rate <60 beats/min and QTc interval ≥500 ms on 12-lead ECG, along with peak T-wave alternans value ≥55.5 μV and documented TdP or VF on 24-hour Holter monitoring, have been identified as independent predictors of LAEs in patients with LQTS. These ECG parameters may serve as valuable early indicators of sudden cardiac death in LQTS patients.