Aortic Stenosis and Atrial Fibrillation Left Atrial Appendage Occlusion—Could We? If So, How and When? (2017)

A Venn diagram which includes the overlap of aortic stenosis and atrial fibrillation presents challenges but also substantial opportunities.1Chugh SS Havmoeller R Narayanan K et al.Worldwide epidemiology of atrial fibrillation: a global burden of disease 2010 study.Circulation. 2014; 129 (doi: 10.1161/CIRCULATIONAHA.113.005119): 837-847Google Scholar 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,2Leon MB Smith CR Mack M et al.Transcatheter aortic-valve implantation for aortic stenosis in patients who cannot undergo surgery.N Engl J Med. 2010; 363 (doi: 10.1056/NEJMoa1008232): 1597-1607Google Scholar 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 short- as well as longer-term outcome.3Tarantini G Mojoli M Windecker S et al.Prevalence and impact of atrial fibrillation in patients with severe aortic stenosis undergoing transcatheter aortic valve replacement.JACC Cardiovasc Interv. 2016; 9 (doi: 10.1016/j.jcin.2016.01.037): 937-946Google Scholar, 4Nuis R-J Van Mieghem NM Schultz CJ et al.Frequency and causes of stroke during or after transcatheter aortic valve implantation.Am J Cardiol. 2012; 109 (doi: 10.1016/j.amjcard.2012.01.389): 1637-1643Google Scholar, 5Yankelson L Steinvil A Gershovitz L et al.Atrial fibrillation, stroke, and mortality rates after transcatheter aortic valve implantation.Am J Cardiol. 2014; 114 (doi: 10.1016/j.amjcard.2014.09.025): 1861-1866Google Scholar, 6Nombela-Franco L Webb JG De Jaegere PP et al.Timing, predictive factors, and prognostic value of cerebrovascular events in a large cohort of patients undergoing transcatheter aortic valve implantation.Circulation. 2012; 126 (doi: 10.1161/CIRCULATIONAHA.112.110981): 3041-3053Google Scholar 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.7Holmes DR Kar S Price JB et al.Prospective randomized evaluation of the Watchman left atrial appendage closure device in patients with atrial fibrillation versus long-term warfarin therapy.J Am Coll Cardiol. 2014; 64 (doi: 10.1016/j.jacc.2014.04.029): 1-12Google Scholar,8Reddy VY, Doshi SK, Kar S, et al. 5-year outcomes after left atrial appendage closure: from the PREVAIL and PROTECT AF trials. J Am Coll Cardiol. 2017; pii: S0735-1097(17)41187-9. doi:10.016/j.jacc.2017.10.021Google Scholar 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)9Harjai KJ Thakur K Young B et al.Suitability for Watchman implantation in TAVR patients with atrial fibrillation.Struct. Heart. 2018; 2: 139-144Google Scholar 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.(1)Some of these patients may be treated with anticoagulation for concerns of leaflet immobility.10Makkar RR Fontana G Jilaihawi H et al.Possible subclinical leaflet thrombosis in bioprosthetic aortic valves.N Engl J Med. 2015; 373 (doi: 10.1056/NEJMoa1509233): 2015-2024Google Scholar Depending on the duration of that therapy to treat that specific problem, LAAO may not be needed.(2)In some patients, even short-term anticoagulation is not felt to be possible. That would be considered an off-label use of the WATCHMAN device in US patients. It must be remembered however that globally, patients with LAAO devices are most commonly not treated with anything other than single or dual antiplatelet therapy post device placement.(3)The timing of WATCHMAN placement is an important issue to be considered. Placement prior to TAVR does not have great appeal as it would delay the TAVR for at least some time, probably until the device endothelializes.During the TAVR procedure itself is a possibility although it might lengthen the procedure. Although WATCHMAN devices have been implanted at the same time as other intracardiac procedures such as WATCHMAN combined with atrial fibrillation ablation, the issue of reimbursement is substantial and may make this prohibitive. With current reimbursement, if two procedures are performed during the same setting, only one would be reimbursed. Accordingly, the procedure could be then reimbursed as a TAVR procedure or LAAO procedure but not both.It is also perhaps more reasonable to consider implantation of a WATCHMAN post TAVR. That could be performed at the time of follow up within a month. The advantage of that is that any vascular access issues would have been resolved and the patient would have recovered from the TAVR procedure. Disadvantages would include a second procedure. In this setting however, reimbursement would not be an issue. The study by Harjai and colleagues is important. It does have several limitations that the authors describe well in terms of its retrospective observational design. There are issues about under estimation of the prevalence of major bleeding, the issues of how do you define labile INR; there is the issue of under documentation of patient compliance and history of falls. Certainly the issue of anticoagulation as part of the potential “standard of treatment of TAVR patients” is an important one. However the bleeding problems associated with approach are really problematic. In summary, it is a very interesting article with very good, very appropriate conclusions—that there are a significant number of TAVR patients with atrial fibrillation who are unsuitable for long-term oral anticoagulation and that there is an unmet need for WATCHMAN implantation in TAVR patients with atrial fibrillation to optimize stroke prevention without the need for anticoagulation and thereby being able to dramatically reduce the bleeding associated with long-term anticoagulant therapy. The author has no conflicts of interest to disclose.