Torsade De Pointes, Short-Coupled Variant

Description

Torsade de pointes is characterized by an electrocardiographic (ECG) pattern of nonuniform but still-organized electrical activity with progressive changes in morphology, amplitude, and polarity of the QRS complexes, the peaks of which twist around the isoelectric baseline before ending spontaneously. In classic torsade de pointes, the coupling interval of the first beat is long (see LQT1, 192500), whereas in this short-coupled variant, the coupling interval of the first beat is very short (summary by Leenhardt et al., 1994).

Clinical Features

Leenhardt et al. (1994) described 14 patients, 7 men and 7 women (mean age, 34.6 years) without structural heart disease, who were referred for the evaluation and treatment of severe syncope; each had at least 1 documented episode of ventricular tachyarrhythmia showing the electrical characteristics of torsade de pointes. Syncope was provoked by emotion in 2 patients and by exercise in 1 patient. In 10 of the 14 patients, degeneration of torsade de pointes into ventricular fibrillation was documented, and the patients required resuscitation; 4 patients had a family history of sudden death. In all 14 patients, the coupling interval of the first beat of the torsade de pointes was very short (around 245 ms; range, 200 to 300 ms), in contrast to the long coupling interval of the first beat in classic torsade de pointes. The morphology of the first beat and of isolated ventricular premature beats were strikingly similar in 9 patients, with a left axis deviation and a left bundle branch block pattern. The morphology was different in the 5 other patients, with right axis and/or right bundle branch block, but the coupling interval was always short. Resting ECGs were normal in all but 1 patient, who had rate-dependent left bundle branch block. Electrophysiologic study of all 14 patients showed no abnormality of basic electrophysiologic parameters, including ventricular refractoriness. Over a mean follow-up period of 7 years, there were 6 deaths: 1 was due to stroke in a hypertensive patient, and the other 5 occurred suddenly, during sleep for 2 patients and in undefined circumstances for the other 3. Of the 8 living patients, 3 underwent placement of an implantable cardioverter-defibrillator (ICD) device.