Atrial fibrillation activates platelets and coagulation in a time-dependent manner: a study in patients with paroxysmal atrial fibrillation.

OBJECTIVES

To determine whether atrial fibrillation (AF) alone affects the fibrinocoagulation system, we examined the relation between fibrinocoagulation activity and duration of AF in patients with paroxysmal AF (PAF).

BACKGROUND

Patients with chronic AF are at higher risk for stroke and a hypercoagulative state. It is not clear whether this hypercoagulative state is attributable to AF alone or to the underlying disease. There are no reports on the fibrinocoagulation properties in PAF.

METHODS

Fibrinocoagulation variables in 21 patients with PAF were measured during AF and 7 days after recovery of sinus rhythm. There were positive correlations between the duration of AF and beta-thromboglobulin, platelet factor 4, thrombin-antithrombin III complex and fibrinogen. These variables increased significantly 12 h after the occurrence of PAF; thus, patients were classified into two groups according to the duration of PAF: PAF-I group (< 12 h, n = 10), PAF-II group (> or = 12 h, n = 11). Nine age-matched, healthy subjects formed the control group.

RESULTS

Levels of beta-thromboglobulin and platelet factor 4 were significantly higher (p < 0.001) by two-way repeated measures analysis of variance (ANOVA), and thrombin-antithrombin III complex and fibrinogen levels tended to be but were not significantly higher (p = 0.06, ANOVA), in the PAF-II group than in the PAF-I group. There were no significant differences between groups in activated partial thromboplastin time, D-dimer or plasmin inhibitor complex.

CONCLUSIONS

These results indicate that AF itself enhances platelet aggregation and coagulation, which are influenced by the duration of AF. The acceleration of platelet activity and coagulability occurred 12 h after the occurrence of AF.