['Electrophysiological studies demonstrate that a short atrial fibrillation cycle length (AFCL) is related with poor outcome of electrical cardioversion (ECV) of atrial fibrillation (AF). We found previously that the mechanical AFCL (AFCL-tvi) and atrial fibrillatory velocity (AFV-tvi) may be determined noninvasively using color tissue velocity imaging (TVI) and closely relates to the electrophysiological AFCL.', 'To evaluate the relation between AFCL-tvi, AFV-tvi, and success of ECV in patients with AF.', 'We prospectively studied 133 patients with persistent AF by performing echocardiography before ECV and measured the AFCL-tvi and AFV-tvi in the right atrium and left atrium. Recurrent AF was monitored.', 'Nineteen (14%) patients had failure of ECV, 42 (32%) remained in sinus rhythm after 1-year follow-up, and 72 (54%) had a recurrence of persistent AF. Patients with immediate ECV failure had a lower median AFV-tvi measured in the right atrium than did patients with a successful ECV: 0.7 cm/s (0.2-1.0 cm/s) vs. 1.7 cm/s (0.9-2.8 cm/s) (P = .008). Patients with maintenance of sinus rhythm after 1 year had a longer AFCL-tvi measured in the left atrium than did patients with recurrence of AF (150 ms vs 137 ms; P = .017) and had a higher AFV-tvi in both atria (1.4 vs. 0.9 cm/s in the left atrium; P = .013 and 2.2 vs 1.4 cm/s in the right atrium; P = .011). Multivariate analyses showed that all atrial TVI parameters were independently associated with the maintenance of sinus rhythm after 1 year.'] Is the mechanical fibrillation pattern of the atrial myocardium associated with acute and long-term success of electrical cardioversion in patients with persistent atrial fibrillation?