ACTIVATION OF THE HEMOSTATIC MECHANISM AFTER PHARMACOLOGICAL CARDIOVERSION OF ACUTE NONVALVULAR ATRIAL-FIBRILLATION

Background Given that the restoration of sinus rhythm after chronic at rial fibrillation is associated with embolic events, anticoagulation i s prescribed before and after pharmacological and electrical cardiover sion. However, the need for anticoagulation in patients with acute atr ial fibrillation (lasting <48 hours) who undergo cardioversion is less clear. In addition, it is not known whether cardioversion to sinus rh ythm determines a hypercoagulable state in these patients. Methods and Results In 21 patients with acute nonvalvular atrial fibrillation, pl asma median concentrations of thrombin-antithrombin complex, a marker of thrombin generation, significantly increased from 2.8 ng/mL (interq uartile range, 2.1 to 4.0 ngimL) on hospital admission to 3.5 ng/mL (i nterquartile range, 2.9 to 6.0 ng/mL) after cardioversion to sinus rhy thm obtained by means of infusion of antiarrhythmic drugs and decrease d to 2.5 ng/mL (interquartile range, 2.0 to 3.5 ng/mL) at the 1-month follow-up visit (P=.04). Similarly, the levels of fibrinopeptide A, a marker of thrombin activity, increased from 1.1 nmol/L (interquartile range, 0.7 to 1.5 nmol/L) at baseline to 1.8 nmol/L (interquartile ran ge, 1.1 to 3.0 nmol/L) after cardioversion and returned to 0.8 nmol/L (interquartile range, 0.6 to 1.1 nmol/L) at the 1-month follow-up visi t (P=.02). Conclusions A significant increase in plasma levels of the markers of thrombin generation and activity was observed in patients w ith acute atrial fibrillation early after pharmacological cardioversio n to sinus rhythm. This is the first biochemical evidence that cardiov ersion of recent-onset atrial fibrillation determines a hypercoagulabl e stale.