[Pharmacological treatment of ventricular tachycardia]

Pharmacological antiarrhythmic therapy is the treatment of first intention for the prevention of ventricular tachycardia (VT). In sustained VT, electrophysiological investigations without treatment enable the induction of VT, the demonstration of its reproducibility, the confirmation of diagnosis (if necessary), the determination of its mechanism and the choice of treatment. In an effort to standardise the technique, a minimum acceptable protocol of stimulations was agreed upon: at least 2 cycles (600 milliseconds and 400 milliseconds) and 3 extrastimuli (S2, S3, S4). The percentage of inducibility (sensitivity) depends on the underlying heart disease and is of the order of 90-95% in coronary artery disease with a history of infarction. Serial electrophysiological studies show non-inducibility of VT with treatment in 20-60% of cases. This result is influenced by the ejection fraction, the type of ventricular arrhythmia (fibrillation or tachycardia) and the antiarrhythmic agent tested. A Class IA, then a Class IC antiarrhythmics or sotalol (if the ejection fraction is over 40%) are evaluated by this technique. Empiric therapy has no place in the management of malignant poorly tolerated arrhythmias. In recurrent, well tolerated arrhythmias which are non-inducible, treatment may be guided by the results of Holter monitoring, providing the patient has a sufficient number of extrasystoles. Exercise stress tests may be useful in effort or catecholamine-induced tachycardias. There is no consensus about the management of non-sustained VT. When these arrhythmias are associated with syncope or cardiac arrest, programmed ventricular stimulation seems indicated. The choice of antiarrhythmic drugs and their results are reviewed.