Abstract
Objectives: The aim of this study was to evaluate the ability of D-Dimer for the diagnosis of left atrial appendage (LAA) thrombus in patients with chronic atrial fibrillation (AF).

Methods: 80 patients with chronic AF who fulfilled the inclusion and exclusion criteria were studied prospectively. 45 patients had LAA thrombus diagnosed by transesophageal echocardiography (TEE) constituted group I (LAA thrombus group). The other 35 patients without LAA thrombus constituted group II. All the 45 patients (100%) in group I with LAA thrombus had elevated D-Dimer levels while only 10 patients (28.5%) in group II without LAA thrombus had elevated D-Dimer levels (P < 0.001). All the patients received oral anticoagulation with warfarin keeping the INR between 2 and 3 for 3 months. TEE was done to all the patients at 3-month follow up.

Results: 12 patients (26.7%) in group I had elevated D-Dimer levels. The number of patients with positive D-Dimer decreased significantly at 3-month follow up (P < 0.001) while on warfarin. LAA thrombus resolved completely in 35 patients (77.8%) at 3-month follow up. In group II, all the 35 patients (100%) had negative D-Dimer levels at 3-month follow up. At 6-month follow up all the patients in group I and II had negative D-Dimer levels (100%).

Conclusion: The sensitivity of D-Dimer for the diagnosis of LAA thrombus is 100%. The specificity of D-Dimer for the diagnosis of LAA thrombus is 71.4%. So, patients with positive and elevated D-Dimer levels should undergo TEE for the diagnosis of LAA thrombus. While a negative D-Dimer test result makes the diagnosis of LAA thrombus is extremely unlikely. Appropriate oral anticoagulation results in complete resolution of LAA thrombus within 6 months.

Key words: Chronic atrial fibrillation; D Dimer; Left atrial thrombi; marevan; warfarin; transesophageal echocardiography.