1. Introduction
Atrial fibrillation (AF) is characterized by rapid and disorganized electrical activation of the atrium which leads to loss of efficient atrial contraction.1, 2 The loss of organized atrial contraction provokes blood stasis especially in the left atrial appendage (LAA) which can be visualized by trans-esophageal echocardiography (TEE) as spontaneous echo-contrast (SEC).3, 4 The blood stasis can serve as a nidus for thrombus formation leading to clinical stroke, a major complication of AF.4-8 Evaluation of hemodynamics of LAA is performed with TEE by detecting SEC of measuring LAA flow velocity. However, TEE is an invasive procedure and procedure-related complications such as esophageal injury can occur. Furthermore, most patients require intravenous sedatives due to pain and inconvenience related with insertion of the TEE probe. Magnetic resonance imaging (MRI), a non-invasive test compared with TEE, can measure the flow volume of LAA.9 Velocity-encoded (VENC) cardiac MRI enables measurement of LAA blood volume during the cardiac cycle and has strong correlation with TEE parameters of LAA hemodynamics.10, 11 Previous reports revealed that the evaluation of LAA blood flow with VENC-MRI can identify blood stasis in LA and LAA.10
The role of radiofrequency catheter ablation (RFCA) in AF patients was largely limited to improvements in the quality of life and subjective symptoms.12, 13 However, recent studies suggest that the beneficial effect of RFCA extends beyond quality of life.14-16 Although the reduction of ischemic stroke by RFCA in AF patients has not been demonstrated in randomized clinical trials, various observational studies suggest that RFCA can reduce the risk of ischemic stroke.15-18Restoration of sinus rhythm might significantly improve hemodynamics of LAA. In the other hand, scar formation due to radiofrequency energy delivery might have adverse influence on LAA. Impact of RFCA on LAA hemodynamics AF patients is not fully evaluated. We aimed to measure the flow volume of LAA before and after RFCA with VENC-MRI in AF patients.