Concomitant left atrial appendage occlusion and transcatheter aortic valve replacement among patients with atrial fibrillation – The WATCH-TAVR Trial
Reported from TCT 2023
Panos Xaplanteris provides his take on WATCH-TAVR results which were presented by Samir R. Kapadia at TCT Congress 2023.
Safety and Efficacy of Left Atrial Appendage Occlusion at the Time of Transcatheter Aortic Valve Replacement - The WATCH TAVR Trial
Why this study – the rationale/objective?
Atrial fibrillation (AF) is a frequent comorbidity in patients with severe aortic valve stenosis (AS) with a prevalence of up to 40%. While the mainstay of stroke prevention in the setting of AF is lifelong anticoagulant therapy, catheter-based left atrial appendage occlusion (LAAO) has emerged as an alternative for patients who experience significant (intracranial or life-threatening) bleeding, have a high bleeding risk (HAS-BLED score >=3), require prolonged triple therapy following angioplasty or have end-stage renal dysfunction.
Transcatheter aortic valve implantation (TAVI) is currently indicated in older patients with severe AS or patients deemed at high surgical risk. The rationale of the WATCH-TAVR study is that the two procedures (TAVI and LAAO) can be combined in order to decrease the thromboembolic risk of patients with severe AS and concomitant AF by circumventing the need for oral anticoagulation.
The study follows the rationale of the LAAOS II study where a similar approach, albeit with surgical LAAO, for patients undergoing cardiac surgery, was shown to be superior to no occlusion on a background of anticoagulation therapy.
How was it executed – the methodology?
349 patients from 34 US centres were included in this randomized trial. 177 were treated with TAVI and LAAO and 172 with TAVI and medical therapy. LAAO was performed by implanting the Watchman 2.5 device and these patients were treated with warfarin and aspirin for 45 days followed by dual antiplatelet therapy until 6 months. Patients in the TAVI and medical therapy group received anticoagulants and/or antiplatelets according to their doctor’s preference. The mean age, CHA2DS2-VASc and HAS-BLED scores were 81 years, 4.9 and 3 respectively. 85.4% of patients were on anticoagulants at baseline and 71.3% were on antiplatelet therapy. Patients were followed up to 24 months after randomization.
The primary endpoint was the combination of all-cause mortality, stroke and bleeding. Of note, the study was designed with the hypothesis that the TAVI and LAAO approach would be non-inferior to TAVI and medical therapy with a margin of 1.5 for the hazard ratio of the primary endpoint.
What is the main result?
At 24 months the TAVI and LAAO was non-inferior (but not superior) to TAVI and medical therapy approach as regards the primary endpoint (33.9% versus 37.2%, HR: 0.86, 95% CI: 0.60-1.22, P for noninferiority <0.001).
The individual constituents of the composite primary endpoint did not differ, with all-cause mortality, stroke and major/life-threatening bleeding being comparable between the two approaches.
Major and life-threatening bleeding was numerically higher in the TAVI+LAAO group during the first 6 months of anticoagulation and dual antiplatelet therapy; the opposite was observed thereafter, with fewer bleedings up to 2 years compared to TAVI and medical therapy.
Arterial and venous thrombosis or embolism was more common for TAVI and LAAO compared to TAVI and medical therapy (9% versus 1.7%, HR: 5.03, 95% CI: 1.47, 17.26) mainly due to venous thrombosis.
More contrast and procedural time were required for the concomitant TAVI and LAAO implantation (49 mL and 38 min more respectively) as compared to TAVI implantation alone.
Critical reading and the relevance for clinical practice
- The WATCH-TAVR trial demonstrates that a concomitant LAAO occlusion with the Watchman 2.5 device and TAVI in patients with AF and severe AS is feasible and non-inferior compared to TAVI and medical therapy alone. This combined approach reduces the number of procedures and use of resources (including intubations for general anaesthesia) for patients who would otherwise have TAVI and would subsequently require LAAO in the future; this is important given the frailty of these patients.
- The Watchman 2.5 device that was used in the trial is now replaced by the new iteration of the device called Watchman FLX owing to its superior sealing properties, better ability to adapt to more LAA anatomies and decreased potential for provoking perforations/pericardial effusions. In addition, Watchman FLX requires less intensive anticoagulation following implantation. It can be hypothesized that these features would translate into more favourable outcomes for patients undergoing a combined TAVI and LAAO procedure as compared to outcomes observed at the WATCH-TAVR trial.
- Interestingly, LAAO occlusion did not result in fewer bleedings compared to medical therapy in this population with high bleeding risk at baseline as captured by their high HAS-BLED score. A reduction in bleeding for those patients who are not exposed to chronic anticoagulation after LAAO would have been intuitively expected. In contrast, serious bleedings were numerically more in the LAAO group in the first 6 months of follow-up and this trend inverted afterwards and up to 2 years. This could be attributed to the need for warfarin and aspirin administration during the first 45 days post-LAAO. Extended follow-up is required in order to establish if serious bleeding will decrease in the long run after LAAO.
- As regards thrombosis, the TAVI and LAAO group had a fivefold increase in arterial and venous thromboses compared to TAVI and medical therapy, mainly due to venous thromboses. This merits attention, despite the fact that thromboses did not result in higher stroke or mortality rates. In addition, it highlights the fact that anticoagulation protects from thrombus formation in all vascular territories and not only at the level of the LAA.
- The trial enrolled patients with AF undergoing TAVI and not only patients at high bleeding risk or having previous serious bleeding under anticoagulation. As transcatheter LAAO is currently reimbursed in many countries only for patients who had previous significant bleeding under anticoagulation, this may hamper the applicability of such a combined TAVI and LAAO approach for every AF patient who will have TAVI.
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