Abstract 638: Differences in Repolarization Patterns between Symptomatic Short QT Syndrome Patients and Subjects with Short QT Interval without Arrhythmic Events
Patients with a short QT syndrome (SQTS) have a high risk for atrial fibrillation and /or ventricular tachyarrhythmias and sudden cardiac death. However, not all individuals in the general population with a short QT interval are at risk for these arrhythmic events. Therefore, we compared ECG characteristics between the symptomatic SQTS patients and subjects with a short QT interval but without a history for arrhythmias, syncope and/or sudden cardiac death. Our study population consisted of 10 SQTS patients (39±19yrs, range 15– 67yrs, males 7) with documented ventricular tachyarrhythmias or aborted sudden cardiac death (SCD), and 12 control subjects (38.8±7.9yrs, range 30–52yrs, males 11) with SQT interval (QTc ≤ 320ms) (mean) without documented arrhythmias or SCD during a long follow-up (29 ± 10 years). A healthy age- and gender matched group of 20 subjects (37.7yr±16.7yrs, range 20–68yrs, males 12) with normal QT interval served as another control group. In addition to standard ECG parameters, additional measurements of repolarization (Jpoint-Tpeak, Tpeak-Tend, Tpeak-Tend/QTc, T wave amplitude) were compared between the groups. Major ECG abnormality in SQTS patients was the Jpoint- Tpeak interval, which was significantly shorter in SQTS (101±18 ms, range from 80 to 120ms, p<0.001 vs. both control groups) compared to subjects with asymptomatic short QT-interval (184±27 ms, range from 150 to 240ms) or matched controls with normal ECG (203±33 ms, range from 160 to 280ms), resulting in 100% accuracy in differentiating the SQTS patients from the others. Short Jpoint-Tpeak interval, reflecting rapid early phase repolarization, is a specific feature of SQTS, which differentiates the SQTS patients from subjects with a benign form of short QT interval on 12-lead ECG.