Short QT syndrome: Should we push the frontier forward?

Abstract

15-year-old boy was resuscitated from ventricular fibrilation (VF). The cardiac arrest occurred while he was at ome resting. The patient had no family history of sudden eath or syncope, and he had never complained of any ardiac symptoms. Initial and all subsequent successive ECGs display short T intervals with tall symmetric T waves on precordial eads (mean QT 283 16 ms, range 245–310 ms; Figure 1). orrected QT intervals using the Bazett formula, calculated hen heart rate was 85 bpm, were 340 20 ms (range 15–375 ms). QTpeak–QTend interval was 80 ms. QT disersion was evaluated at 30 ms on 12-lead ECG. Calcium nd potassium blood levels were consistently in the normal ange. Except for the first echocardiogram, which displayed nitial pericardial effusion after resuscitation maneuvers and ransient septal thickening, no other argument in favor of a yocarditis was found. Coronary angiograms, further reeated echocardiograms, and cardiac magnetic resonance maging were unremarkable. Repeated 24 hour-ECG recordings displayed permanent inus rhythm with poor adaptation of QT intervals to the eart rate, as shown by the lack of lengthening of repolarzation after pauses. Infrequent isolated monomorphic venricular ectopies were documented. QT shortening contined with isoproterenol infusion or during exercise testing shortest QT 200 ms) with documentation of short-coupled 200 ms) isolated ectopic ventricular beats with left bundle ranch block, left-axis deviation with isoproterenol (30 g/ in). There was a linear relationship between QT interval nd heart rate during exercise testing (curve slope 0.7 ms/ pm, R 0.9). Drug challenge (1 mg/kg intravenous jmaline in 5 minutes) administered to reveal a Brugada