Relationship between mean platelet volume and atrial thrombus in patients with atrial fibrillation.

Platelets and clotting cascade play a major role in development of atrial thrombus in patients with atrial fibrillation. The mean platelet volume (MPV) reflects platelet size and is considered a marker and determinant of platelet function because larger platelets are hemostatically more reactive than platelets of normal size, increasing the propensity to thrombosis. We have investigated the relationship between MPV and left atrial thrombus in patients with persistent atrial fibrillation. A total of 205 consecutive patients (men: 67.3%, women: 32.7%; mean age: 62.3 ± 12.8) who had persistent atrial fibrillation, undergone transesophageal and transthoracic echocardiography. Study individuals were divided into two groups. Group 1 (n: 96, 46.8%): atrial fibrillation complicated with atrial thrombus and group 2 (n: 109, 53.2%): atrial fibrillation free of thrombus, which was identified by means of transesophageal echocardiogram. The MPV, platelet distribution weight, and platelet count were measured. There was no difference in terms of MPV, platelet distribution weight, and platelet count in two groups. MPV was not correlated with thrombus and spontaneous echo contrast. Left atrial thrombus was included in multivariate logistic regression analysis and only low ejection fraction was a predictor of left atrial thrombus (P = 0.04). This is first report showing that MPV is not related with left atrial thrombus in patients with atrial fibrillation. According to our result, MPV cannot be considered as an index of left atrial thrombus in patients with atrial fibrillation.