Severe mitral stenosis with atrial fibrillation--a harbinger of thromboembolism.

OBJECTIVE: To determine the frequency of Left Atrial thrombus in patients suffering from severe mitral stenosis with atrial fibrillation.

METHODS: A cross sectional descriptive type study was conducted in the Echocardiography department of the National Institute of Cardio Vascular Diseases (NICVD) Karachi from October 1, 2007 to March 17, 2008. A total of 100 consecutive adult patients with severe Mitral stenosis (MS) and Atrial Fibrillation (AF) were included in this study. 12-lead Electrocardiography was done once clinical and echocardiographic features revealed Sever MS. Patients with signs of AF were selected and Transthoracic Echocardiography (TTE) was obtained to detect Left Atrial Thrombus. Transesophageal echocardiography (TEE) was performed whenever thrombus could not be found with TTE and / or nature of the mass could not be confirmed.

RESULTS: Among 100 patients studied; there were 52 males and 48 females. TTE was performed in all patients and LA thrombi were detected in 24% patients. TEE was performed in remaining 76% patients and additional 14 patients with LA thrombi were detected in this subgroup. Therefore a total of 38% of the patients with LA thrombi were documented. Among them, 6% had clots in LA body while LA appendage clots were found in 32% of patients. Left atrial dimension was found to be relevant (P-value = 0.004) with the presence of thrombus in patients with severe mitral stenosis associated with atrial fibrillation. Left atrial spontaneous echo contrast (LASEC) was found in 54% of patients but it was not found to be relevant with the presence of LA thrombus (P = 0.75).

CONCLUSION: Left atrial thrombus was present in 38% patients with severe mitral stenosis associated with atrial fibrillation. Larger left atrial diameter is a stronger predictor of presence of LA thrombus