Catheter ablation for atrial fibrillation and left atrial appendage occlusion: to combine in a single procedure?

This editorial refers to ‘Combining left atrial appendage closure and catheter ablation for atrial fibrillation: 2-year outcomes from a multinational registry’, by K.P. Phillips et al., on pages 225--231. Atrial fibrillation (AF) is the most common heart rhythm disease and can be associated with severe symptoms, impaired quality of life, and an increased cardiovascular morbidity and mortality because of stroke or heart failure.1 Prevention of thromboembolism is the mainstay treatment of AF, and improving stroke prevention is of paramount clinical importance. Though elimination of AF or reduction of AF burden by catheter ablation (CA) may result in a significant reduction in stroke risk, long-term continuation of oral anticoagulation (OAC) after CA is currently a topic of debate.2 However, early and late recurrences are common after CA and therefore current guidelines and expert consensus recommend continuation of systematic OAC after a blanking period (e.g. 2–3 months) based primarily on the patient’s CHA2DS2-VASc score and not on the apparent success or failure of the ablation procedure (Class II B).1,3 An alternative method for stroke prevention in AF patients is the exclusion of the left atrial appendage (LAA) from the systemic circulation, as ∼91% of cardiac thrombi in AF patients are found in the LAA.4 This catheter-based therapy may be especially attractive in AF patients with high bleeding risk or a history of bleeding as a long-term solution for prevention of LAA-mediated thromboembolism and would not increase the risk of bleeding complications like long-term use of OAC.1 Since many patients with drug-resistant symptomatic AF also exhibit a high thrombo-embolic and/or bleeding risk, the combination of CA and the mechanical closure of LAA is in the focus of current research. However, the optimal combination strategy has not been convincingly established and interventional LAA closure can be performed as a stand-alone procedure or alongside concomitant CA for AF as a combined procedure. In this issue of EP-Europace, Phillips et al.5 report long-term outcome data of this combined treatment approach in a single procedure. Of 1140 patients with AF included in two multicentre, prospective, real-world registries, 142 patients underwent concomitant CA and percutaneous LAA occlusion with the Watchman device. The results show high rates of successful device implantation and a good procedural safety with complication rates similar to those reported for CA or LAA closure alone. After a mean follow-up of 2 years, 92% of patients remained off OAC. The non-procedural major bleeding rate was 1.09 per 100-patient years, corresponding to a 70% relative risk reduction when compared to the expected bleeding risk on warfarin according to the HAS-BLED score. The rate of ischaemic stroke was 0.36 per 100-patient years which represented a 93% relative risk reduction compared to the predicted rate by the mean CHA2DS2-VASc score without OAC. The combined thrombo-embolic endpoint consisting of ischaemic stroke, transient ischaemic attack, or systemic thromboembolism was also significantly reduced (1.09 per 100-patient years; 84% relative risk reduction). The present study is of high interest due to its timely topic and clinical relevance, but obviously limited by its non-randomized design and a missing control population consisting of patients undergoing CA and LAA occlusion in separate procedures. The effectiveness of CA regarding the long-term maintenance of sinus rhythm after the combined intervention has not been assessed and only one of the commercially available LAA closure devices has been used. Consequently, conclusions regarding the potential advantages or disadvantages of the hybrid approach compared to separated procedures are not completely possible. However, when compared to previously published studies and expected event rates, the present real-world registry data suggest a low peri-procedural risk and good long-term safety and efficacy regarding the prevention of bleeding and thrombo-embolic events.5 These findings confirm and expand previous reports regarding combined CA and mechanical LAA occlusion.6–8 What do we conclude from these data? What are the potential advantages and disadvantages of a combined single procedure? The most obvious advantage of a combined approach in patients requiring CA and LAA closure is the need for a single access to the left atrium. Considering the incidence of major complications related to AF ablation and percutaneous LAA closure which share the same procedural steps (vascular access, OAC, transseptal puncture), the combination of CA with LAA closure in a single procedure reduces the risks associated with a repeated LA procedure such as pericardial effusion, tamponade, and/or access-site complications. Moreover, shorter total required duration of OAC, fewer hospitalizations and potentially costs as well as improved compliance and quality of life of patients undergoing the combined procedure may be advantages compared to procedures performed in a staged fashion. However, combining ablation with LAA mechanical occlusion may also bear some disadvantages due to considerable tissue inflammation/oedema and potential undersizing of the device with subsequent per-device leak. According to the data by Phillips et al.5 and other multicentre registries,6–9 we can conclude that a combined procedure appears to be a safe and effective procedure and consequently a careful patient selection is necessary to maximize its benefit. So the question is, which patients are most likely to benefit from concomitant CA and LAA occlusion? In cases with recurrent episodes of AF despite complete pulmonary vein isolation, additional trigger sites outside the pulmonary veins have been identified. In this regard, LAA emerged as a potential important trigger of AF and target for CA in non-responders to pulmonary vein isolation.10 A drawback of this ablation strategy is the electromechanical dissociation of LAA with an increased thrombo-embolic risk despite sufficient OAC.11 Although the available data regarding the risk of thrombus formation after electrical LAA isolation are not entirely consistent and an association with ablation strategies (wide area vs. circular LAA isolation) is discussed,10,11 this patient population seems particularly interesting for concomitant mechanical LAA occlusion. Despite some concerns (e.g. regarding the choice of the correct closure device size given an oedematous reaction after LAA isolation), a previously published study suggests that concomitant LAA closure after electrical isolation of the LAA is feasible, safe, and effective.12 Moreover, AF patients with a bleeding history and/or contraindications to OAC seem to be ideal candidates for a combined approach. However, randomized comparisons between concomitant CA, irrespective of the ablation site and technique, and LAA closure vs. separate procedures are currently not available. Only randomized studies can prove an advantage or at least non-inferiority of the combined approach and will be provided by future investigations (e.g. OPTION trial, NCT03795298). In case of positive results in favour of the combined treatment, cost, and reimbursement considerations have to be resolved as well, as most national health care systems and insurance companies do not reimburse both procedures if performed at the same time, making the combined procedure an economic pitfall for many institutions. In the absence of randomized data, we suggest that separate procedures for CA and LAA occlusion should currently remain the standard of care. In selected cases, however, the available non-randomized data including the study by Phillips et al.5 justify a concomitant approach in a single procedure. Irrespective of the implantation strategy, decision making for LAA closure should be based on guidelines, which recommend that percutaneous LAA occlusion may be considered in patients with contraindications for long-term anticoagulation treatment (Class IIb, level of evidence B).1 A more liberal use in clinical practice requires a randomized comparison to state-of-the-art anticoagulation therapy including direct oral anticoagulants, which is currently in progress (CLOSURE-AF trial, NCT03463317). In conclusion, concomitant CA for AF and mechanical LAA closure is a feasible and safe approach in selected patients with symptomatic non-valvular AF, high risk of stroke, and contraindications for long-term OAC. A potential benefit of the hybrid procedure compared to separate interventions remains to be investigated. Before we have these data, we should keep it with Albert Einstein: ‘Everything should be made as simple as possible, but not simpler’. Conflict of interest: none declared. The opinions expressed in this article are not necessarily those of the Editors of Europace or of the European Society of Cardiology.