Recent data suggest that elevated plasma levels of homocysteine could be associated with atrial fibrillation (AF). The aim of our study was to investigate whether elevated plasma Hcy levels were predictive of the recurrence rate of AF after successful electrical cardioversion. Eighty-three patients (63 +/- 12 years, 61.4% men) with persistent AF lasting at least 7 days were included after successful electrical cardioversion. Echocardiography and plasma homocysteine assay were performed prior to cardioversion and patient baseline characteristics were obtained. Patients were monitored for a period of 18 months. The patients were divided into two groups using a cut-off value for the last quartile of plasma homocysteine concentration (> 14.4 micromol/L). Kaplan Meier analysis showed a statistically significant difference in AF recurrence rates between both groups after 18 months (P = 0.02, log rank test). Cox proportional hazards multivariate analysis showed that predictors of AF recurrence were the duration of AF (OR 1.05, 95% CI 1.02-1.08, P = 0.00), treatment with amiodarone (OR 0.39, 95% CI 0.21-0.72, P = 0.00), and homocysteine level < or = 14.4 micromol/L (OR 0.39, 95% CI 0.21-0.73, P = 0.00). We found that the homocysteine levels determined prior to electrical cardioversion can predict recurrence of AF after successful restoration of sinus rhythm.