Antiarrhythmic Potential of Acetaminophen in Mammalian Myocardium

Despite the fact that acetaminophen has been used in mainstream Western Medicine for more than 100 years its cardiovascular actions are poorly understood. In the present study we tested the hypothesis that acetaminophen has antiarrhythmic potential. Two groups of dogs, vehicle‐ and acetaminophen‐treated were studied. Only ventricular arrhythmias defined by the Lambeth Convention were investigated. Dogs were exposed either to 60min of regional myocardial ischemia followed by 180min of reperfusion (n=7), to ouabain administration (n=7), or to hyperkalemia (KCl, n=5). Ventricular premature beats, ventricular salvos, ventricular bigeminy, and ventricular tachycardia were monitored during baseline and experimental conditions. Heart rate did not differ significantly between vehicle‐ and acetaminophen‐treated dogs under any condition. Neither did ventricular arrhythmias differ between groups during baseline conditions. Conversely, the average number of ventricular ectopic beats was significantly less during ischemia and reperfusion in the acetaminophen‐treated group, e.g. 28±4 vs 6±1 (P<0.05). Similarly, per cent ectopy during reperfusion in vehicle‐ and acetaminophen‐treated groups was , respectively, 1.4±0.4 and 0.4±0.2 (P<0.05). The frequencies of ventricular premature beats, ventricular bigeminy, and ventricular tachycardia were also significantly lower in the presence of acetaminophen. Similar results were obtained in ouabain‐ but not potassium‐treated dogs. Our results reveal that systemic administration of acetaminophen in a therapeutic dose has previously‐unreported antiarrhythmic properties. Supported by McNeil/ J&J Cosat