gms | German Medical Science

Critical for the diagnosis of primary electrical diseases such as the long QT-syndrome, the Brugada syndrome and the short QT syndrome is the ECG. However, fluctuations of the depolarization and repolarization with a change from a clear pathological to an only suspicious or even normal pattern may complicate diagnosis. Phenotypic overlap findings are known with e.g. precordial QT polongation in patients with a Brugada syndrome. Aim of the actual study was to screen for a shortening of the QT time in a collective of patients with a Brugada syndrome for potential overlap syndromes.

Patient and methods: 44 consecutive patients with a Brugada syndrome (mean age 44 ± 12 years, 28 men, 16 women) were enclosed in the study. Apart from the index ECG consecutive follow-up ECGs were analyzed with respect to morphological changes of the cardiac repolarization (type I-, II-, III-ECG or normal finding). Furthermore, the QT interval was determined.

Results: The mean QT interval of all patients and ECGs was 411 ± 33 msec. 40% of ECGs presented with a normal finding. In contrast three patients, which were symptomatic with syncopes and aborted sudden cardiac death presented with a shortened QT-interval of 327±10ms (relative QT Interval 85.7%±0.6) in all and not only in the precordial leads. One patient showed during follow-up a type-I ECG, the other patients presented apart form the QT shortening a type-I pattern during intravenous drug challenge (ajmaline). Mean ventricular refractory periods were shortened (170±8ms) in this group and in one patient ventricular fibrillation could be induced during programmed ventricular stimulation. Clinical implications: 1) 7% of the patients with a Brugada syndrome presented with a shortened QT interval. 2) At present it is unclear whether we deal with a short QT syndrome or a Brugada syndrome. 3) It has to be examined, whether gain-of-function mutations with a shortened cardiac repolarization period may induce a type I ECG.