Incidence of left atrial thrombus prior to catheter ablation of atrial fibrillation: Is it time for atrial cardiomyopathy evaluation?

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To the Editor,
We read with great interest the article by Gunawardene et al.1 We would like to add some commentaries about the presence of left atrial thrombus in anticoagulated patients with atrial fibrillation (AF) before pulmonary vein isolation.
In this recently published article, the authors concluded that: “Preprocedural transesophageal echocardiography (TEE) may be dispensed in patients with a CHA2DS2‐VASc score ≤1,” because “a cut off value for a CHA2DS2‐VASc score of ≤1 has a 100% sensitivity for exclusion of left atrial appendage thrombus.” In some patients (“with an increase in the CHA2DS2‐VASc score, a reduced LVEF of less than 30%, a history of nonparoxysmal AF, or presence of hypertrophic cardiomyopathy”), a “TEE should be performed leading to an individualized approach in this regard.”
In another study of similar design,2 the authors obtained an identical result: A “CHA2DS2‐VASc score < 2 has a maximal‐negative predictive value for the presence of left atrial/left atrial appendage thrombi in anticoagulated patients with AF planned for pulmonary vein isolation.” In addition, left atrial appendage thrombi were significantly associated with persistent AF (P = 0.002), heart failure (P < 0.001), diabetes mellitus (P = 0.017), spontaneous echo contrast (P < 0.001), and low left atrial appendage‐peak emptying velocity (P < 0.001).
Analyzing the literature quoted by Gunawardene et al.1 (table 7), we remarked that in our study with 681 patients, we found almost the same prevalence of left atrial/left atrial appendage thrombi before AF ablation (1% vs. 0.78%).2 Moreover, the most important thing is that in this population, we proposed an algorithm, making a distinction between paroxysmal and nonparoxysmal AF and the decision not to perform a TEE was restricted to patients without heart disease.2
In these patients, the presence of left atrial/left atrial appendage seems to be not depending on an appropriate anticoagulation level3 or anticoagulation treatment type (with vitamin K or nonvitamin K antagonists),1 neither of clinical risk factors4 as CHA2DS2‐VASc scores ≥2; history of nonparoxysmal AF; chronic heart failure, as well as nonclinical ones like4: dilated left atrium; hypertrophic cardiomyopathy; left atrial appendage morphology (≥3 left atrial appendage lobes), or the presence of sinus rhythm at the time of TEE.
We agree that “an individual risk stratification on preablation TEE should be conducted for each patient prior to AF ablation, instead of making a generalized statement on whether preablation TEE is dispensable or not in all patients undergoing AF ablation.” Probably, it is time for an individualized approach in every patient with AF, appropriate anticoagulated or not, because left atrial fibrosis is the key. Hypercoagulability causes atrial fibrosis and promotes AF5 due to thrombogenic fibrotic atrial cardiomyopathy occurrence6; left atrial fibrosis induced by structural remodeling is associated with stroke risk.7 This vicious circle should be analyzed in each patient.
Therefore, probably, it is time for atrial cardiomyopathy evaluation to understand the incidence of left atrial thrombus prior to catheter ablation of AF.
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