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Aortic Stenosis and Atrial Fibrillation Left Atrial Appendage Occlusion—Could We? If So, How and When?

A Venn diagram which includes the overlap of aortic stenosis and atrial fibrillation presents challenges but also substantial opportunities. As the incidence of both aortic stenosis and atrial fibrillation increase with advancing age, in concert with increasing risk of stroke and transient ischemic attacks (TIAs), multiple factors need to be considered. As documented in the PARTNER trial, preexisting atrial fibrillation was seen in 33% of high risk patients and in up to 50% in patients who were deemed inoperable for conventional surgery. In this population, preexisting atrial fibrillation was a predictor of poor shortas well as longer-term outcome. Whether this association represents a cause/effect relationship or is a manifestation of more advanced structural heart disease with more fibrosis and dilatation of atria and ventricles is uncertain. In such patients, application of left atrial appendage occlusion (LAAO) technology has great potential value. This value may be the result of the documented advantages of decreasing stroke or eliminating the need for long-term anticoagulation. In the randomized trials of LAAO as well as in the large registries, those beneficial outcomes have been documented with improvement in survival, a 70% reduction in bleeding compared with warfarin, and an approximately 80% reduction in hemorrhagic stroke. Importantly these benefits were seen in patients 95% of whom had been able to discontinue warfarin anticoagulation. Whether these salutary effects might be seen in patients with underlying severe aortic stenosis is unclear. It is the focus of the WATCH-TAVR trial (NCT03173534). In one single center study, Harjai and colleagues (this issue) set out to determine how frequent a clinical case could be made for deploying a WATCHMAN LAAO device in patients with documented atrial fibrillation who had already undergone TAVR. It did not study a strategy of identifying patients who might be considered for WATCHMAN prior to TAVR. The 113 patients had been either high risk STS PROM score aortic stenosis or extremely high risk for conventional surgical aortic valve replacement (SAVR). In this group, the authors identified 48 patients (43%) who either had preexistent or new onset atrial fibrillation. They then used conventional criteria for identifying patients who might be considered appropriate for LAAO. Namely, patients had a median CHA2DS2-VASc score of 4 and it was ≥ 3 in 46 (96%). The authors assessed the bleeding score using the imperfect but still widely used HAS-BLED score which was ≥ 4 in 29 (60%). The risk of bleeding was estimated to be high in 31 patients (65%) and a major bleeding event in the past was identified in 18 of these patients (38%). Accordingly, the patients were at high risk for both stroke/systemic embolization as well as bleeding. Finally, there had been problems in this patient group with anticoagulation prior to TAVR in at least 50% because of labile INRs or moderate or high risk falls. The majority of patients (80%) had been on warfarin for stroke prevention and so presumably could have been able to take short-term treatment with anticoagulation for six weeks as per the WATCHMAN instructions for use. There are multiple issues to be considered in how to position this data going forward.