Antibodies against myosin in sera of patients with idiopathic paroxysmal atrial fibrillation.

INTRODUCTION

Circulating autoantibodies against myosin heavy chain have been detected in patients with ventricular myocarditis and in patients with dilated cardiomyopathy. This study investigated the presence of antibodies against myosin in sera of healthy control persons as compared with patients with idiopathic paroxysmal atrial fibrillation refractory to antiarrhythmic therapy.

METHODS AND

RESULTS

An SDS-PAGE (sodium dodecylsulfate polyacrylamide gel electrophoresis) procedure, followed by Western blotting with homogenates and membrane fractions of human left ventricular and atrial specimen as antigens, was used to analyze sera of 10 patients with idiopathic paroxysmal atrial fibrillation and 10 age-matched healthy control subjects. Circulating immunoglobulin G reactivity against cardiac myosin heavy chain was detected in 6 patients (60%) as compared with 1 control subject (10%). This difference was statistically significant (P < 0.05). All patients with idiopathic paroxysmal atrial fibrillation who showed reactivity against myosin heavy chain also had specific reactivity in their sera that exhibited reactivities to both ventricular and atrial cardiac myosin heavy chain isoforms.

CONCLUSION

This study demonstrates the presence of circulating autoantibodies against myosin heavy chain in a significant percentage of patients with idiopathic paroxysmal atrial fibrillation and raises the possibility of an autoimmune process in some patients with paroxysmal atrial fibrillation.