How Short is Too Short: A Patient with Short QT Syndrome

Objectives: We report a case of a 16-year–old boy, previously healthy, after syncope while warming up for soccer training. Attendees immediately initiated cardiopulmonary resuscitation until ambulance arrived. The defibrillator documented ventricular flutter/fibrillation, treated by desynchronized cardioversion. Return of circulation was achieved and on admission to the hospital the patient suffered from atrial fibrillation followed by another cardioversion. A third cardioversion was necessary 10 days thereafter for recurrent ventricular fibrillation. Comprehensive workup as laboratory tests, echocardiography, cerebral and coronary computer tomography remained inconclusive, and the patient was equipped with an external defibrillator vest. At that point, he was transferred to our unit.

Methods: Previous medical history was reviewed, excluding cardiorespiratory symptoms or syncope. Familiy history was negative for sudden cardiac death or congenital cardiac lesions. Laboratory tests were inconclusive for electrolyte, hormonal, or metabolic disorders. Echocardiography showed normal cardiac function and dimensions. A 12-lead electrocardiogram (ECG) revealed bradycardic sinus rhythm of 34 bpm and a corrected QT interval (QTc) of 350 ms with high tenting T-wave morphology. Repetitive ECGs and a 24-hour ECG were performed.

Result: All ECGs documented QTc-intervals shorter than 360 ms. The shortest QTc measured was 320 ms at a heart rate of 47 bpm. Short-QT syndrome (SQTS) was diagnosed according to the ESC guidelines. As recommended the patient underwent ICD implantation. In addition, we initiated an antiarrhythmic therapy with sotalol.

Conclusion: SQTS is a rare underdiagnosed channelopathy, partly because duration of QTc-intervals varies between several ECGs at rest. To reliably diagnose SQTS we recommend serial ECGs in patients surviving episodes of sudden cardiac death. Genetically negative phenotypes occur in more than 75%. Due to an exceptional high rate of inadequate shocks (missensing of T-waves by the ICD), additional drug treatment is recommended.