Worsening of arrhythmias during pharmacological treatment.

The widespread use of antiarrhythmic agents to control severe life-threatening arrhythmias evidenced the possibility of a worsening of arrhythmias induced by the same drugs. We performed a retrospective analysis studying the worsening phenomenon in patients who underwent pharmacological invasive and non invasive antiarrhythmic tests to choose the drug to be administered in the chronic treatment. Particularly we reviewed: 101 acute pharmacologic non invasive tests for "stable" ventricular ectopic beats using computerized automatic continuous recording system which allows quantitative and qualitative evaluation of arrhythmias. The drugs tested were: Propafenone (25 patients), Disopiramide (25 patients), Tocainide (11 patients), Lorcainide (8 patients), Lorajmine (13 patients), Nadolol (9 patients). In accordance with Vallebit et al., we considered arrhythmias worsening criteria: the onset of non sustained or sustained ventricular tachycardia; an increase of four fold the number of ventricular ectopic beats and/or ten fold the repetitive forms. A worsening of arrhythmias was observed in 4/101 (3.9% patients); 1/9 treated with Nadolol, 1/25 with Propafenone, 1/35 with Disopiramide, 1/13 with Lorajmine. For one young patient the worsening phenomenon could be considered a toxic picture, because of the very high drug plasmatic levels (Lorajmine) observed for the whole duration of the sustained VT induced from the drug. For the remaining 3 patients the response resambles a paradox effect. 34 pharmacologic invasive tests in 30 patients with common recurrent ventricular tachycardia, during electrophysiologic endocavitary study. The drugs tested were: Propafenone (12 patients), Amiodarone (11 patients), Ajmaline (4 patients), Tocainide (3 patients), Lorcainide (2 patients), Lorajmine (1 patient), Disopiramide (1 patient).(ABSTRACT TRUNCATED AT 250 WORDS)