Torsades de pointes induced by nonantiarrhythmic drugs.

Torsades de pointes with its bizarre twisting pattern and its association with QT prolongation is no longer a potential cardiac arrhythmia unique to the proarrhythmic effects of the antiarrhythmic drugs. Even though certain agents have been classified as nonantiarrhythmic drugs, in instances of electrolyte or metabolite imbalance, heart disease, and/or drug-drug interaction, a proarrhythmic effect is always present. This risk increases with malnourished and/or elderly persons coupled with a poor medical follow-up system. Particularly, the concurrent use of terfenadine and astemizole with the macrolide antibiotics or with the antifungal agents ketoconazole, itraconazole is contraindicated.