Acute haemodynamic effects of the antiarrhythmic agent pirmenol in cardiac patients: a comparison with lidocaine.

The acute haemodynamic effects of pirmenol, a new Class 1 antiarrhythmic agent, were investigated in a double-blind comparison with lidocaine and placebo. Three groups of 10 patients each received either pirmenol as a 50 mg intravenous injection followed by a 2.5 mg min-1 infusion, or lidocaine as a 75 mg injection followed by a 3 mg min-1 infusion, or placebo. Mean plasma pirmenol concentrations during the 30 min infusion period were 2.3-2.5 mg l-1, and were considered to be therapeutically effective. Compared to measurements taken during a baseline phase of 15 min duration, pirmenol increased heart rate by 10 beats min-1 (P less than 0.001) and mean arterial pressure (MAP) by 5 mmHg (P less than 0.001). It also increased systemic vascular (P less than 0.05) and pulmonary arterial resistances (P less than 0.01). Left ventricular end-diastolic pressure (LVEDP) was not increased significantly. Cardiac index and left ventricular work index remained unchanged. Lidocaine induced a comparable increase in MAP (6 mmHg; P less than 0.001) and elevated LVEDP (2.8 mmHg; P less than 0.05) and did not affect left ventricular work index. Echocardiographic left ventricular ejection fraction was reduced more by pirmenol (-0.05; P less than 0.001) than by lidocaine (-0.03; P less than 0.05), but the greater reduction may partly be explained by the increase in heart rate. Primenol did not induce excessive circulatory responses or side-effects in any patient. Intravenous administration of pirmenol results in increased heart rate and afterload but has little effect on preload. The myocardial depressant effect is relatively slight, and comparable to that of lidocaine.