PQ Segment Depression in Short QT Syndrome Patients: A Novel Marker for Diagnosing Short QT Syndrome?

BACKGROUND: Patients with a short QT syndrome (SQTS) have an increased risk for atrial, ventricular tachyarrhythmias and/or sudden cardiac death. PQ segment depression (PQD) is related to atrial fibrillation and carries a poor prognosis in the setting of acute inferior myocardial infarction and is a well defined ECG marker of acute pericarditis. OBJECTIVES:The aim of this study was to evaluate the prevalence of PQD in SQTS and to analyze the association with atrial arrhythmias. METHODS:12-lead ECGs of SQTS patients were evaluated for PQD in all leads and for QT intervals in lead II and V5. PQD was defined as ≥ 0.05 mV (0.5 mm) depression from the isoelectric line. RESULTS: A total of 760 leads from 64 SQTS patients [mean age 36 ± 18 years, 48 males (75%)] were analyzed. PQD was seen in 265 (35%) leads from 52 (81%) patients and was more frequent in leads II, V3, aVF, V4, and I [n=43 (67%), n=30 (47%), n=27 (42%), n=25 (39%), n=25 (39%), respectively]. Nine of 64 patients (14%) presented with atrial tachyarrhythmias and all of them had PQD. CONCLUSIONS: Two of 64 patients (81%) with SQTS reveal PQD. As PQD is rarely observed in healthy subjects, this ECG stigma may constitute a novel marker for SQTS in addition to a short QT interval.