Torsade de pointes complicating acute myocardial infarction: the importance of autonomic dysfunction as assessed by heart rate variability.

Torsade de pointes is a polymorphic ventricular tachycardia associated with QT-interval prolongation rarely reported to occur in the setting of an acute myocardial infarction. Autonomic dysfunction has been implicated as a major stimulus for the development of this dysrhythmia. We describe the case of an 80-year-old woman who presented with an acute myocardial infarction and progressive QT-interval lengthening. An 89-beat run of torsade de pointes occurred during the time of the peak creatine phosphokinase (CPK) without electrolyte abnormalities or antiarrhythmic therapy. Assessment of autonomic tone using power spectral analysis of two consecutive 24-h Holter recordings was performed indicating that a transient decrease in heart rate variability and increase in sympathetic tone preceded the tachyarrhythmia. This case shows the potential usefulness of heart rate variability analysis as a marker for autonomic dysfunction and arrhythmogenesis, particularly during myocardial ischemia.