Long-term use of procaine amide following acute myocardial infarction.

The safety of long-term prophylactic antiarrhythmic therapy with procaine amide was studied in 78 patients recovering from acute myocardial infarction. Patients were randomly allocated to a control or treatment group and followed monthly for up to 2 years with ambulatory ECG monitoring and measurement of serum drug level, antinuclear antibody (ANA) titer, LE preparation, blood count, BUN, and SGOT. Early reactions forced discontinuation of therapy in nine of 39 treated patients within the first 3 weeks. Late reactions were observed in 14 of 16 patients who took procaine amide for 3 months or longer. Every patient on therapy for 1 year or longer demonstrated elevation in ANA titer. Comparison of monitoring data between these two groups revealed no difference in the incidence of occasional or frequent premature ventricular beats. However, during the first 6 months, treated patients tended to have fewer major arrhythmias. There were fewer sudden deaths among treated patients, but this difference did not reach statistical significance at the 5% level. It is concluded that the high incidence of toxic reactions precludes widespread use of long-term prophylactic procaine amide therapy. More precise identification of a sudden death-prone population might justify such therapy in such selected cases.