RESUMO
BACKGROUND: Sex hormones play an important role in the development of cardiovascular disease. Testosterone and estradiol have been reported to be down-regulated in subjects with coronary artery disease and heart failure, but has not been studied in atrial fibrillation (AF). HYPOTHESIS: Levels of sex hormones may be associated with susceptibility to lone AF in men. METHODS: Fifty-eight male subjects who had electrocardiographic evidence of paroxysmal or chronic AF and a structurally normal heart on echocardiography were enrolled. Subjects were excluded if they had been taking angiotensin-converting enzyme inhibitors (ACEI), angiotensin receptor blockers (ARB), or statins within 3 mo or had a history of coronary artery disease, rheumatic heart disease, cardiomyopathy, significant valvular disease, hyperthyroidism, or hypertension. Fifty-eight controls were recruited from a healthy outpatient population. Serum total testosterone and estradiol levels were determined using a commercially available radioimmunoassay. RESULTS: Mean levels of testosterone were significantly lower in subjects with lone AF when compared with controls (476 ng/dl versus 514 ng/dl, p = 0.005). No significant differences were found in the estradiol levels between the 2 groups (31.9 pg/ml versus 32.4 pg/ml, p = 0.789). CONCLUSION: Reduced testosterone levels may be associated with susceptibility to lone AF in men.