The incidence of rheumatic heart diseases have not declined in our population .Rheumatic heart diseases, often neglected by media and policy makers, is a major burden in developing countries where it causes most of the cardiovascular morbidity and mortality in young people, leading to about 250000 deaths per year worldwide. Mitralstenosis is one of the most common complications of rheumatic heart diseases in our community. A treatment of choice in suitable cases is percutaneous Mitral Commissurotomy .Preoperative evaluation for Percutaneous Mitral Commissurotomy typically requires trans-esophageal echocardiogram (TEE) for the presence of LA thrombus. TEE is currently considered the gold standard for LA thrombus detection given its favorable sensitivity and specificity . With recent advances,CMRis now becoming another reliable diagnostic method for evaluation of thrombus in the left atrium, particularly when delayed imaging is performed.

Whereas TEE is a semi-invasive procedure, CMRis totally non-invasive . Effectiveness of left ventricular thrombus detection by CMR has been validated, and it is now becoming a preferred imaging modality for evaluation of left ventricular thrombus . Moreover, in patients undergoing pulmonary vein isolation,Cardiac Magnetic Resonance was validated against TEE for LA & left atrial appendage . To our knowledge, there are few data regarding the utility of Cardiac Magnetic Resonance for detection of LA thrombus in patients undergoing Percutaneous Mitral Commissurotomy.

Patients with Mitral stenosis that admitted in Assiut University hospital -Cardiovascular Department for doing Percutaneous Mitral Commissurotomy Will undergo Trans-esophageal echo and Cardiac Magnetic Resonance for detection of left atrial Thrombus and left atrial appendage thrombus. Investigators will compare the result of Cardiac Magnetic Resonance with the results of Trans-esophageal echo for seen the sensitivity and specificity of Cardiac Magnetic Resonance in compare to Trans-esophageal echo who is the gold standard imaging for detection of left atrial and left atrial appendage Thrombus.Data will be presented as mean ± standard deviation for continuous variables and frequency for categorical variables.

• Patients with and without thrombus will be compared using independent (unpaired) Student t test for continuous variables and the Fisher exact test for categorical variables, or their non-parametric equivalents, after testing the data for normality.
• Diagnostic performance of each CMR component will be calculated in the standard manner.

Inclusion Criteria:

• Severe mitral stenosis .
• Significant dyspnea.
• Favorable anatomical characteristics for Percutaneous Mitral Commissurotomy as assessed by trans-thoracic echo.

Exclusion criteria:

• Critically ill patients including hemo-dynamically unstable patient.
• Implanted pacemakers/cardiac defibrillators and other electronic implants.
• Cerebral aneurysm clips.
• Pregnancy.
• Significant renal impairment