Effect of heparin on serum free-fatty-acids, plasma catecholamines, and the incidence of arrhythmias following acute myocardial infarction.

The effect of intravenous heparin in a therapeutic dosage on cardiac arrhythmias in patients with indubitable acute myocardial infarction was investigated. The value of serum free-fatty-acids (F.F.A.s) and plasma catecholamines in the prediction of patients vulnerable to serious arrhythmias was also studied.Heparin produced a significant rise in F.F.A., maximal within 10 minutes of injection, but did not increase the incidence of cardiac arrhythmias.No relationship was found between the incidence of arrhythmias and the initial levels of F.F.A. or adrenaline. No correlation was obtained between F.F.A. and plasma catecholamine levels. Heparin did not have a consistent effect on plasma catecholamines. Initial control plasma noradrenaline concentrations, however, were found to be significantly correlated with the incidence of subsequent arrhythmias. It is suggested that the level of plasma noradrenaline may be a valuable predictive guide to those patients likely to develop significant arrhythmias after acute myocardial infarction.