Editorials
Is Transesophageal Echocardiography Necessary in Every Case of Atrial Fibrillation Ablation?
2018 Volume 82 Issue 11 Pages 2701-2702
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2018 Volume 82 Issue 11 Pages 2701-2702
Pulmonary vein isolation (PVI), a cornerstone of catheter ablation for atrial fibrillation (AF), can be accomplished safely and effectively more than ever before with the technological innovations related to ablation. This leads to an increase in the number of AF ablations, and approximately 50,000 cases of AF ablation are currently carried out in Japan.1 Prior to the AF ablation procedure, transesophageal echocardiography (TEE) is performed in many cases for screening the presence/absence of left atrial thrombus (LAT). The 2017 HRS/EHRA/ECAS/APHRS/SOLAECE expert consensus statement on AF ablation positioned TEE as a Class IIa recommendation.2 Considering the increase in the number of AF ablations, it would be difficult to perform TEE prior to AF ablation in all cases.
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Recently, the safety and efficacy of performing the ablation procedure on uninterrupted direct oral anticoagulant (DOAC) therapy have been reported.3–5 Furthermore, a recent study suggested the safety of the ablation procedure on uninterrupted apixaban and rivaroxaban without TEE screening.6 As a result, some physicians have questioned the need for preprocedural TEE in all cases. Balouch and colleagues assessed trends in TEE use, the rate of LAT detection, and incidence of periprocedural cerebrovascular accidents (CVA) from 2010 to 2015.7 They showed that, despite the decreasing frequency of preprocedural TEE, the rate of CVA did not change, which suggested that the number of patients undergoing preprocedural TEE can be reduced without an increase in periprocedural adverse events. Indeed, the aforementioned expert consensus statement reported that the percentage of the writing group members performing preprocedural TEE for all patients undergoing AF ablation was only 51%.2 However, the prevalence and risk factors of LAT in AF patients prescribed DOAC were not completely clarified.
In this issue of the Journal, Harada and colleagues evaluated 407 AF patients on DOAC undergoing TEE 1 day before ablation and examined the prevalence and risk factors of LAT.8 They showed that preprocedural TEE detected LAT in 18 patients (4.4%), and that persistent AF and inappropriately reduced DOACs were independent risk factors for LAT. These results were compatible with those of previous similar studies. LAT was previously reported to be detected by preprocedural TEE before AF ablation in 2.1–4.4% of patients.9–13 Alqarawi and colleagues reported that no cases of LAT were detected in AF patients on DOAC with preprocedural TEE.14 In this report, the percentage of persistent AF was low compared with recent studies (29% vs. 35–87%).9–11,13,14 This result supports the suggestion that persistent AF is a strong risk factor for LAT. In addition to persistent AF, heart failure9–11 and left atrial dilatation9,11 are reported to be independent risk factors for LAT in patients undergoing AF ablation. Harada and colleagues reported inappropriately reduced DOACs as a risk factor for LAT.8 It was reported that inappropriately reduced DOACs did not reduce major bleeding and rather increased cardiovascular hospitalization.15 Ablation procedure on uninterrupted proper dose of DOACs was shown not to increase periprocedural bleeding events.3–5 Thus, we should avoid inappropriate dose reduction of DOACs, especially in patients undergoing AF ablation. Taken together with the results of the previous studies, preprocedural TEE would be recommended for patients with persistent AF, those with paroxysmal AF complicated with heart failure or left atrial dilatation, and those being treated with an incorrect dose of DOACs.
Patients with LAT detected prior to AF ablation are contraindicated for the procedure. To reduce the frequency of preprocedural TEE, we need to establish a method for identifying the patient group with no LAT risk. It has been reported that no patients with CHA2DS2-VASc score of 0 had LAT.8,9 Frenkel and colleagues, however, described a case of persistent AF and LAT even though the CHA2DS2-VASc score was 0.10 As shown above, persistent AF is a strong risk factor of LAT. Thus, preprocedural TEE may be necessary in persistent AF patients even if the CHA2DS2-VASc score is 0. Harada and colleagues describe 4 patients with paroxysmal AF in whom LAT was detected by preprocedural TEE; 2 were on an inappropriately reduced dose of DOACs and the other 2 had CHA2DS2-VASc scores of 3 and 4, respectively.8 They suggest that preprocedural TEE may be safely omitted in paroxysmal AF patients when their CHA2DS2-VASc score is 1 or 2 and an appropriate dose of DOACs is prescribed. Bertaglia and colleagues showed that among variables including CHA2DS2-VASc score, only a history of heart failure, diabetes, and previous stroke or transient ischemic attack predicted LAT.13 A new scoring system that can predict LAT more precisely and effectively is needed to identify patients in whom preprocedural TEE can be safely excluded.
Finally, for treatment of pre-procedurally detected LAT, some previous studies reported the efficacy of switching DOACs to warfarin at a high target prothrombin time-international normalized ratio.9–13 The efficacy of DOACs for treating LAT has been reported,10,12 but still remains to be established. Harada and colleagues report that a regular dose of dabigatran was effective in dissolving preprocedural LAT.8 Although the number of patients with LAT was small and the protocol for the treatment of LAT was not prespecified, a regular dose of dabigatran was suggested as a therapeutic option for LAT. Further studies are needed to establish the efficacy of dabigatran for LAT.
H.O. has no relevant disclosures. K.O. received Speakers’ Bureau/Honorarium from Boehringer Ingelheim, Bayer, Daiichi-Sankyo.
