CARDIOVASCULAR JOURNAL OF AFRICA • Volume 34, No 3, July/August 2023 AFRICA 185 et al. analysed data from 32 studies with a total number of 4 621 patients. They showed thromboembolic events among 92 patients; 82% of embolic episodes occured in the first three days and 98% within 10 days of cardioversion.66 The most recent meta-analysis of studies in patients undergoing pharmacological and electrical cardioversion showed a periprocedural stroke or systemic embolism rate of 0.41% in the NOAC group versus 0.61% in the VKA group.67 Considering that the mean incidence of thrombus in the LAA despite NOAC treatment is 5%, the conclusion emphasises the fact that not every thrombus in the LAA will cause a stroke during cardioversion of the arrhythmia. According to current knowledge, it is not easy to answer the question whether to perform TEE or not before cardioversion in AF patients using NOACs. According to the authors, a practical decision-making algorithm proposed by Gorczyca et al. is very interesting.68 The authors analysed commonly known risk factors of LAA thrombus based on results from previous studies and they merged them in a simple screening path. Gorczyca et al. recommend pre-procedural TEE in patients who had left atrial appendage thrombus (LAAT) in the past, regardless of treatment strategy, and also in those with any suspicion of unsystematic NOAC use. In the remaining patients, the necessity for TEE should be decided upon after considering individual thromboembolic risk. The authors suggest TEE in patients with any strong LAAT risk factors, such as previous intracardiac thrombus, irregular use of NOAC, inappropriate dose reduction of NOAC, previous stroke/TIA/systemic embolism, CHA2DS2-VASc score ≥ three points, glomerular filtration rate < 60 ml/min/1.73 m2, reduced left ventricular EF, or moderate or severe left atrial enlargement. Management of patients with a thrombus in the LAA Embolic material in the LAA is associated with a high risk of cerebrovascular events. Leung et al. demonstrated a high (10.4%) annual incidence of stroke and systemic embolism, and a 15.8% rate of annual mortality in patients with embolic material in the LAA, despite treatment with vitamin K derivatives.69 In another study of 317 patients with recent stroke, a thrombus in the LA was detected in 20% of patients, all of which were located in the LAA.70 If such a material is detected, electrical cardioversion should be abandoned. Unfortunately, the 2021 EHRA practical guidelines do not specify the exact treatment method to dissolve the embolic material in the LAA, which has arisen despite chronic anticoagulant treatment.62 This is due to the lack of studies with adequate power and endpoints that can determine the best management strategy. Before the widespread use of NOACs, strategies for managing embolicmaterial intheLAA,despite theuseof oral anticoagulation, included stricter INR control, adding or changing treatment to low-molecular weight heparin, or increasing the VKA dose to achieve an INR in the range of 3–4 .71-73 The use of NOACs creates new therapeutic possibilities in the presence of embolic material in the LA and/or its appendage; however, available data are limited to a small number of studies and case reports. A prospective study has been published assessing the effect of rivaroxaban on a newly detected thrombus in the LAA, the X-TRA study.74 Sixty patients were enrolled in the study, of which full data were available for 53 patients, and the mean CHA2DS2-VASc score was two points. Three-quarters of the patients (76.7%) had not been treated with anticoagulants before, and the remainder were treated with suboptimal or ineffective doses of VKA. Follow-up TEE showed that after six weeks, there was resolution in 41.5% of patients, reduction in thrombus size in 19%, no change in 17%, and an increase in size in 22.5% of patients. The authors of this study simultaneously performed a retrospective, observational study (CLOT-AF). Finally, complete data, with control echocardiography, were obtained for 96 patients, most of whom were treated with VKA. Resolution (total resolution or reduction) of thrombotic material in the LA/ LAA was demonstrated in 62.5% of the patients. A prospective, randomised trial, RE-LATED AF-AFNET 7 is currently underway to compare the efficacy of dabigatran 2 × 150 mg with phenprocoumon (INR 2–3) in the treatment of LAA thrombus; 110 patients are planned to be included in the study.75 Moreover, the publication by Marisco et al., which reviews the literature on the effects of NOACs on LA/LAA thrombus, is interesting.76 It is worth mentioning the retrospective study by Mitamura et al., which included 198 patients treated with dabigatran anticoagulation due to AF (98 patients received a dose of 2 × 150 mg), who underwent TEE before electrical cardioversion.77 Dabigatran was used for up to three weeks in 21% of patients, and up to six weeks in 55% of patients. LA thrombi were found in 4% of the studied population: one patient who was treated with 2 × 150 mg dabigatran and seven patients treated with 2 × 110 mg dabigatran. Echocardiography was repeated in six patients, at the earliest after 23 days in one patient, and among the others after a minimum of six weeks. Complete resolution of the thrombotic material was observed in five patients. One patient was treated with a dose of 2 × 150 mg, two patients had an increased dose from 2 × 110 mg to 2 × 150 mg, and one patient was switched to warfarin. In the EMANATE study, a thrombus was detected in 30 apixaban-treated patients and in 31 heparin/VKA-treated patients. Another follow-up TEE was performed, after an average of 37 days, among 23 patients (77%) in the apixaban group and 18 (58%) in the heparin/VKA group. The resolution of thrombotic material was found in 12/23 (52%) patients treated with apixaban and in 10/18 (56%) patients treated with VKA.10 In the RIVA-TWICE study, Piotrowski et al. showed that a strategy with rivaroxaban 15 mg twice daily seemed to be safe and may have dissolved LAA thrombus in seven of 15 included patients (46.7%) who had been treated before with rivaroxaban 20 mg once a day.78 Kołakowski et al. analysed data of 129 patients with LAA thrombus despite adequate anticoagulation treatment and compared the effectiveness of four different strategies of thrombus resolution (all 181 cycles): switch to different mechanism, switch to similar mechanism, implementation of combination therapy (i.e. adding antiplatelet therapy), and deliberate no change in treatment.79 They showed that any change in treatment was three times more effective than deliberate no change in treatment, but no particular strategy seemed to be more effective than another. The overall effectiveness was 51.9% regardless of the number of cycles, and 42.6% for the first cycle of treatment.
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