[Myxedema as a cause of QT syndrome and recurring ventricular tachycardia].

QT-prolongation and ventricular tachycardia of the "torsade de pointes" type are rare in hypothyroidism. We describe a woman with myxoedema coma secondary to hypopituitarism who initially presented a bizarre ECG. Predominant features were excessively prolonged QT intervals, ventricular bigeminy with extreme monophasic ST elevations and alternation of the isoelectric line. Repeated bouts of ventricular tachycardia needed rigorous therapy, including several DC shocks. It is suggested that the unusual ECG finding was due to large local differences in duration of myocardial action potentials.