Although contraindication to OAC is the most common indication for LAAO there is no standardised strategy for antithrombotic medication post-LAAO. For example, LAAO with Watchman should be followed by 45 days of warfarin plus aspirin therapy, and then aspirin monotherapy for life. This strategy arises from PROTECT AF trial protocol and does not take into consideration patients with contraindications to OACs.10 In the ASAP study protocol warfarin was replaced by clopidogrel or ticlopidine.13 Dual anti-platelet therapy for a period of 1 to 3 months and aspirin for up to 6 months is recommended after LAAO with an Amplatzer device (either ACP or Amulet), however, this strategy is empirical and comes from experience with other Amplatzer closure devices; yet there are no data to support it.14,15 Therefore, in real world clinical practice, antithrombotic therapy after LAAO is individualised based on anecdote rather than clinic trial evidence. Physicians should take into account the patient’s history of bleeding, comorbid medical conditions, the completeness of LAAO, and potential for device thrombosis, etc.
Incomplete LAAO is defined as the presence of a leak on color flow Doppler on transesophageal echocardiography (TEE).22,23 A small leak (1–5 mm colour flow jet) is not infrequent after LAAO with the Watchman or the ACP device, but it was not reported to be associated with adverse clinical outcome.14,22,23 Post LAAO device thrombosis on follow-up TEE occurs in approximately 4 % of patients and is usually successfully treated with a brief period (e.g. 4 weeks) of OAC or low molecular weight heparin. Similar to incomplete LAAO, device thrombosis has not been associated with increased adverse event rates.10,14 Management of device thrombosis, however, can be a challenge especially for patients with a very high risk of bleeding, and there remain few available data to guide treatment and follow-up strategies.
The LAA has a relatively fragile, thin-walled structure and considerable variability exists among patients. Moreover, a transseptal approach is almost always needed for endocardial LAAO, whereas a dry pericardial puncture is used for epicardial LAAO. Therefore, it is clear that the procedure requires special operator skills and has a significant learning curve. The most common safety event after LAAO is serious pericardial effusion.11,14 Periprocedural stroke, device embolisation and access-related major bleeding have also been reported. Nevertheless, procedural safety is anticipated to improve as operators increasingly perform LAAO and several other structural heart disease interventions and newer devices with improved design features become readily available.24
Another significant challenge for LAAO therapy will be to prove its non-inferiority (or superiority) to the novel OAC drugs. Currently, there have been no randomised comparisons between these therapies. One argument against the widespread adoption of LAAO therapy is that the use of aspirin post-LAAO carries a bleeding risk equivalent to apixaban. However, the study on apixaban showing such low bleeding events excluded all patients with prior bleeding and recruited in general a low-risk population (average CHADs 2.1).25 Indeed, there exist a considerable number of patients who are contraindicated to all antithrombotic drugs, and in these patients the safety and efficacy of LAAO without any post-procedure antithrombotic medication should be tested. Several special patient populations could potentially benefit from LAAO: patients with severe renal impairment who are extremely difficult to manage with warfarin and cannot take the novel OACs, patients on dialysis or patients who suffer a ‘stroke on OAC’, one of the few occasions when OAC is not stopped after the procedure. Finally, the severity of stroke in the presence of a LAAO device needs to be assessed.