Sinusoidal ventricular tachycardia associated with flecainide acetate.

New pharmacologic agents have been developed which are highly effective in suppressing ventricular premature beats, but their chronic efficacy in patients with sustained ventricular arrhythmias remains uncertain. We observed the appearance of ventricular tachycardia with an unusual sinusoidal QRS complex in three of five such patients treated with flecainide acetate, 200 mg twice daily. Our experience suggests that the early reports of successful suppression of ventricular premature beats in stable patients may not be directly applicable to sicker patients with recurrent sustained ventricular arrhythmias. In these patients, life-threatening arrhythmias may appear as the first manifestation of drug toxicity.