ClinicalOperator Experience and Outcomes after Transcatheter Left Atrial Appendage Occlusion with the Watchman Device
Introduction
As the population ages, there will be an estimated 6–12 million people with atrial fibrillation (AF) in the United States [1]. AF is an important cause for ischemic stroke and can cause systemic embolization. Anticoagulation is recommended for majority of patients based on stroke and bleeding risks as evaluated by CHA2DS2-VASc and HAS-BLED scores [2,3]. For AF patients at high risk of stroke and bleeding, left atrial appendage occlusion (LAAO) can be considered. The Watchman device (Boston Scientific, Inc., Marlborough, MA, USA) is the only LAAO device approved for use in the United States. The device has been evaluated in two randomized control trials: Percutaneous left atrial appendage closure for stroke prophylaxis in patients with atrial fibrillation (PROTECT AF) and Prospective randomized evaluation of the Watchman Left Atrial Appendage Closure device in patients with atrial fibrillation versus long-term warfarin therapy (PREVAIL) trials [4,5]. The EWOLUTION registry outside the US and the post FDA approval US clinical experience from the STS/TVT LAAO registry have reported even higher implant success rates and fewer complications than in the randomized control trials [6,7]. A recent meta-analysis also demonstrated that LAAO occlusion is a safe and effective stroke prevention strategy in patients with AF [8].
Outcomes with emphasis on operator volume and experience have not been studied systematically. Outcomes with focus on operator subspecialty training-electrophysiologists (EP) versus interventional cardiologists (IC) have also not been evaluated. Recent data among patients undergoing TAVR demonstrated a learning curve with higher operator volume being associated with improved outcomes [10,11]. Likewise, higher operator volume has been shown to have better outcomes in stroke patients undergoing mechanical thrombectomy [12]. This study was designed to address this gap in knowledge. The questions this study attempts to answer are: (a) does operator experience influence outcomes and technical success after LAAO procedure with Watchman (b) does operator specialty (IC vs. EP) influence outcomes and technical success after LAAO procedure; (c) is LAAO closure with Watchman subject to a learning curve with improved outcomes after a learning curve is achieved.
Section snippets
Study population
The study population was obtained from a prospective registry of Left Atrial Appendage Occluder (LAAO) patients at Banner University Medical Center, Phoenix, Arizona, USA from 08/01/2015 to 11/01/2018. Data were obtained on 425 consecutive patients, age 18 years and older who were diagnosed with atrial fibrillation (AF), CHA2DS2-VASc Score ≥2 points and underwent LAAO for primary/secondary prevention of stroke. Data on variables were collected according to the definitions and standards of the
Baseline characteristics
From August 2015 to November 2018 there were 425 consecutive patients who underwent LAAO procedure at Banner University Medical Center. The mean age among all patients was 75 ± 8 years. There were 59% (n = 251) males and the majority (379, 89%) of patients were Caucasians. The median BMI was 28.3 (Interquartile Range [IQR]: 25.3, 32.9). Mean CHA2DS2-VASc score was 4.5 ± 1.3 points and mean HASBLED score was 3.9 ± 1.0 points. There were slightly more LAAO procedures performed by IC compared to
Discussion
The principal findings of this study are (1). Unlike other structural heart procedures, LAAO closure with Watchman is not subject to a learning curve and volume outcome relationship. (2). The real-world MACE rates are higher than those reported in clinical trials (3). There is no difference in outcome when the procedure is performed by an electrophysiologist or an interventional cardiologist.
For complex surgical procedures, the volume-outcome debate has been ongoing for years. In a study from
Limitations
Although the data was collected prospectively, the retrospective nature of the study creates a potential for selection bias. However, all the data was collected using standardized definitions, conforming to the standards of the ACC-NCDR/LAAO registry. Since this is a single center experience the results may not be generalizable. Due to the high procedural success rate and the low incidence of complications reported in literature, the number of cases for every single ‘Operator’ in this study may
Conclusion
This study was the first real world experience evaluating the relationship between operator volume and outcomes among patients undergoing the Watchman LAAO procedure. This study demonstrated that unlike other structural heart procedures like TAVR, the LAAO with the Watchman device is not subject to a learning curve and volume outcome relationship. Additionally, electrophysiologists and interventional cardiologists performed equally well. After, an initial learning curve related to transseptal
Acknowledgments
We thank Vidette Villarreal-Argente, F.N.P., Claire Kelly, F.N.P., and Wendy Endreson for their tireless efforts coordinating the care of these patients.
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Dr. Sawant and Dr. Seibolt contributed equally to the study.