ANTIBODIES AGAINST MYOSIN IN SERA OF PATIENTS WITH IDIOPATHIC PAROXYSMAL ATRIAL-FIBRILLATION

Myosin Antibodies in Atrial Fibrillation. Introduction: Circulating au toantibodies against myosin heavy chain have been detected in patients with ventricular myocarditis and in patients with dilated cardiomyopa thy, This study investigated the presence of antibodies against myosin in sera of healthy control persons as compared with patients with idi opathic paroxysmal atrial fibrillation refractory to antiarrhythmic th erapy. Methods and Results: An SDS-PAGE (sodium dodecylsulfate polyacr ylamide gel electrophoresis) procedure, followed by Western blotting w ith homogenates and membrane fractions of human left ventricular and a trial specimen as antigens, was used to analyze sera of 10 patients wi th idiopathic paroxysmal atrial fibrillation and 10 age-matched health y control subjects, Circulating immunoglobulin G reactivity against ca rdiac myosin heavy chain was detected in 6 patients (60%) as compared with 1 control subject (10%). This difference was statistically signif icant (P < 0.05), All patients with idiopathic paroxysmal atrial fibri llation who showed reactivity against myosin heavy chain also had spec ific reactivity in their sera that exhibited reactivities to both vent ricular and atrial cardiac myosin heavy chain isoforms, Conclusion: Th is study demonstrates the presence of circulating autoantibodies again st myosin heavy chain in a significant percentage of patients with idi opathic paroxysmal atrial fibrillation and raises the possibility of a n autoimmune process in some patients with paroxysmal atrial fibrillat ion.