Role of Activated Protein C Resistance in Left Atrial Thrombogenesis in Patients with Mitral Stenosis

Activated protein C resistance (APC-R) is the most common inherited cause of clinically apparent venous thromboembolism. Previous data indicate that left atrial thrombus (LAT) formation is a common complication in mitral stenosis (MS) and a hypercoagulable state exists in these patients. The aim of this study was to invastigate the association between APC-R and LAT formation in patients with MS. Seventy-seven consecutive patients with rheumatic MS were included in this study. Transesophageal echocardiography was performed on all patients to assess the presence of any thrombus or spontaneous echo contrast (LASEC) in the left atrial cavity or appendage. Thirty four of the patients had LAT and 43 did not. Prevelance of APC-R was smiliar between the two groups of patients with and without LAT (23% vs 16%, p=0.425). LAT(+) patients had higher incidence of atrial fibrillation (AF, 74% vs 51%, p=0.046) and LASEC (71% vs 19%, p