Sustained-Release Procainamide-induced Reversible Granulocytopenia after Myocardial Infarction

Abstract

A 71-year-old man with paroxysmal atrial fibrillation who had a previous anterior myocardial infarction exhibited granulocytopenia 8 days following the administration of oral sustainedrelease procainamide (750mg/day). The plasma concentrations of procainamide and Nacetyl procainamide were at subtherapeutic levels. Discontinuation of procainamide led to complete recovery. A bone marrow aspiration showed slight hypoplasia with normocellular marrow. Lupus erythematosus (LE) and antinuclear antibody (ANA) tests were negative. The frequency and relationship of granulocytopenia caused by sustainedrelease procainamide in patients with tachyarrhythmias are briefly discussed, and prior reported cases are reviewed. Precautionary measures for the early recognition of this grave hazard in exposed patients are advocated. The physician should be aware of this complication before initiating treatment with this drug.