Introduction: Hemodynamics of left atrial appendage (LAA) is an important factor for future risk of ischemic stroke in atrial fibrillation (AF) patients and velocity encoded cardiac magnetic resonance imaging (VENC-MRI) can evaluate blood flow volume of LAA without any invasive procedures. We aimed to evaluate the impact of radiofrequency catheter ablation (RFCA) on LAA hemodynamics via MRI evaluation. Methods and Results: Consecutive RFCA cases in a single arrhythmia center were retrospectively analyzed. A total of 3,120 AF patients who underwent first RFCA were analyzed. Among these patients 360 patients had both pre- and post-RFCA VENC-MRI evaluation. Atrial fibrillation was non-paroxysmal in 174 (48.3%) patients. Mean VENC-MRI (ml/sec) was significantly improved after RFCA with 49.75±32.97 and 71.92±34.94 for pre- and post-RFCA, respectively. Patients with non-paroxysmal AF (∆VENC-MRI = 29.71±35.30 vs. 14.42±40.94; p < 0.001) and low pre-RFCA VENC-MRI (∆VENC-MRI = 50.64±28.92 vs. 16.72±38.39; p < 0.001) had significantly higher improvement in VENC-MRI. Those who experienced late recurrence before post-RFCA MRI had significantly less improvement in LAA flow volume (∆VENC-MRI = 15.55±41.41 vs. 25.75±37.00; p = 0.016). Similar results were obtained after adjusting covariates. Conclusions: Radiofrequency catheter ablation can significantly improve hemodynamics of LAA in AF patients. The beneficial effects were most prominent in non-paroxysmal AF, those who had low pre-RFCA VENC-MRI, and those without late recurrence. Whether the improved hemodynamics of LAA after RFCA actually leads to reduced risk of ischemic stroke should be evaluated in future trials.

Introduction: Open irrigation ablation catheters are now the standard in radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF). Among various irrigation catheters, laser-cut slit-based irrigation system (Cool Flex and FlexAbility) has a unique design to cool the catheter tip more efficiently. We aimed to assess the safety of slit-based irrigation catheters regarding prevention of procedure-related ischemic complication in AF patients undergoing RFCA. Methods and Results: The analysis was performed with Korea University Medicine Anam Hospital RFCA registry. Procedure-related ischemic complication was defined as ischemic stroke or transient ischemic attack (TIA) occurring within 30 days after RFCA. Patients were divided into 3 groups: non-irrigation, hole-based irrigation, and slit-based irrigation catheter groups. A total of 3,120 AF patients underwent first RFCA. Non-irrigation, non-slit-based irrigation, and slit-based irrigation catheters were used in 290, 1,539, and 1,291 patients, respectively. As compared with non-irrigation and non-slit-based irrigation catheter groups, slit-based irrigation catheter group had significantly older age, higher prevalence of non-paroxysmal AF, large left atrial size, and decreased left atrial appendage flow velocity. The CHA2DS2-VASc score was not different among the 3 groups. Procedure-related ischemic complication occurred in 17 patients (0.54%) with 16 ischemic strokes and 1 TIA event: 5/290 (1.72%), 11/1,539 (0.71%), and 1/1,291 (0.08%) events in non-irrigation, non-slit-based irrigation, and slit-based irrigation catheter groups, respectively (p = 0.001). Slit-based irrigation catheter was superior in direct comparison with non-slit-based irrigation catheter (0.71% vs. 0.08%; p = 0.009). Conclusions: Slit-based irrigation catheters were highly effective in preventing procedure-related ischemic complications.