Is Left Atrial Appendage Occlusion Really Efficacious in Avoiding Administrating Anticoagulant Drugs for the Prevention of Cardioembolic Events in Patients With Atrial Fibrillation?

摘要

Left atrial appendage occlusion (LAAO), in particular withWatchman device [1] has become the leitmotiv of several recentcardioembolic prevention campaigns for atrial fibrillation (AF).The rational of the LAAO lies in the fact that the vast majority ofcardioembolic events, at the level of cerebral, mesenteric, splenicor peripheral vascular districts, would depend on the detachmentof embolic fragments from the left atrial appendage. There aremany points open to discussion and in-depth reasoning. For example it is very interesting to make comparisons between LAAOand anticoagulant therapy. In the latter, the support to the clinicaldecision brought by transesophageal echocardiography (TEE) israther limited, because the exclusion of the existence of a thrombus within the left atrial appendage with the use of TEE does notexempt the treating physician from the task of prescribing an anticoagulant therapy, once more than 48 h have passed since theonset of AF. In fact, due to its low sensitivity and consequent poornegative predictive value, TEE is usually omitted in the currentoperational process for the management of AF (paroxysmal, persistent or long-lasting persistent). Instead, the AF managementinvolves the systematic adoption of therapy with non-vitamin Kantagonist anticoagulant drugs, as in the cases of non-valvular AF,or with warfarin, for valvular AF. On the contrary, in the case ofa clinical picture poorly compatible with chronic anticoagulanttherapy, for example an AF episode that occurs in a Werlhof’sdisease patient [2], TEE is usually practiced, and the treating physician carefully evaluates the possible findings, i.e., 1) completenegativity; 2) “smoke” or 3) “sludge” patterns or, as the extremepart of this continuum 4) overt positivity. The latter is defined bythe clear documentation of thrombus in the left atrial appendage.Only in the cases in which the signals of activation of the atrialthrombogenesis are present, i.e., the last three cases, the indicationto the LAAO is put forward. Instead the anticoagulation is preferred in case of totally negative response to the TEE. The reasonis that LAAO cannot be undertaken lightly in all patients with AF.Thus, provided that certain conditions are met [2], the interventional approach by Watchman device should be offered only to patients with absolute or relative contraindications to the anticoagulant therapy. Really, LAAO by Watchman in at least 10% of casesfails and in a further 20% of cases is incomplete (persistence ofperiprosthetic leaks and/or potentially embolic appendage (atriumpatency due to abnormal anatomy)). In cases of LAAO proceduralfailure, anticoagulation is mandatory. Therefore in AF patients atlow risk of cardioembolic events who can benefit from a simpleanticoagulation, the commonly adopted strategy is to avoid practicing LAAO. Furthermore LAAO with Watchman device doesnot exempt the treating physician from anticoagulation in at least30% of cases, i.e., those with residual peri-device leak, device failure or device embolization [3]. Finally the puncture of the interatrial septum for the introduction of this device entails the creationof a fairly wide discontinuity, i.e., an iatrogenic atrial septal defect,which requires in the most challenging cases an antiplatelet therapy with chronic clopidogrel or an anticoagulant. Therefore, in theface of such an uncertain outcome, is it still correct to say sic etsimpliciter that LAAO allows avoiding anticoagulant or antiplatelet therapy in patients with chronic atrial fibrillation?.