Mean platelet volume is elevated during paroxysmal atrial fibrillation: a marker of increased platelet activation?

Paroxysmal atrial fibrillation might be a risk factor for stroke such as chronic atrial fibrillation. We examined the relation between mean platelet volume and paroxysmal atrial fibrillation to determine the effect of paroxysmal atrial fibrillation on the thrombotic state via elevated mean platelet volume. Mean platelet volume is a marker of platelet size, function, and activation. Increased mean platelet volume reflects active and large platelets that release more thromboxane A2 than smaller ones. We hypothesized that mean platelet volume is elevated in patients with paroxysmal atrial fibrillation. The study population comprised 103 consecutive patients who were detected to have paroxysmal atrial fibrillation by 24-h Holter monitoring and 87 control individuals with normal Holter monitoring. Mean platelet volume and inflammatory parameters were measured. Comprehensive clinical and echocardiographic data were collected. Patients with aortic and mitral stenosis, hyperthyroidism, hypothyroidism, malignancy, infection, and pregnancy were excluded from the study. Mean age of the patients was 63 +/- 11 vs. 45 +/- 14 years (P < 0.001) in paroxysmal atrial fibrillation and control groups, respectively. Fifty-seven patients (55%) in paroxysmal atrial fibrillation and 19 (21%) (P < 0.001) patients in control group were men. Mean platelet volume was significantly higher in the paroxysmal atrial fibrillation group when compared with control group (10.0 +/- 2.0 vs. 8.3 +/- 1.5 fl, respectively; P < 0.001). C-reactive protein (18.5 +/- 28 vs. 3.8 +/- 2 mg/l, respectively; P = 0.004) and erythrocyte sedimentation rate (21 +/- 21 vs. 12 +/- 7 mm/h, respectively; P = 0.01) were also higher in the paroxysmal atrial fibrillation group. There was no difference in white blood cell and platelet counts between groups. In a multivariate analysis, elevated mean platelet volume was associated with the occurrence of paroxysmal atrial fibrillation before and after adjustment for age and sex. Our results indicate that inflammatory markers such as C-reactive protein and erythrocyte sedimentation rate and the marker of platelet size and activity mean platelet volume are elevated in patients with paroxysmal atrial fibrillation.