Discussion
Preliminary data from this multicentre study suggest that use of NOACs appears to be effective and safe in HCM patient undergoing catheter ablation of AF. The incidence of thromboembolic events was low with both VKA and NOAC. A non-significant but numerically higher rate of major bleeding and cardiac tamponade in patients on VKA versus NOAC was observed.
Several landmark trials have demonstrated that NOACs are at least as effective as VKA for prevention of thromboembolic events of AF [10-13]. However, no randomised data are available on the effectiveness of NOAC in the HCM population. Similar to our findings, four observational studies have suggested that NOACs, compared to VKA, are associated with a similar or lower rate of thromboembolic and bleeding events in subjects with HCM and AF [14-17]. Current HCM guidelines from the European Society of Cardiology suggest the use of NOACs as a second-line drugs in patient with concomitant AF [2]. According to the European Heart Rhythm Association 2018 Practical Guide on Oral Anticoagulants , HCM patients might be eligible for NOACs [4]. The 2014 American Heart Association/American College of Cardiology/Heart Rhythm Society guidelines for AF (confirmed in 2019) state that NOAC “might represent another option to reduce the risk of thromboembolic events, but data for patients with HCM are not available” [3, 18].
Catheter ablation represents an effective treatment for symptomatic drug-refractory AF [19-20]. However, the intra- and post-procedural thromboembolic risk is not negligible and requires effective anticoagulation. In fact, both manipulation of the catheters and creation of lesions inside the left atrium can lead to local thrombus formation [6]. There is a significant body of evidence showing that NOACs can be safely used in patients undergoing catheter ablation of AF, with a similar or lower rate of bleeding and thromboembolic complications compared to VKA [6, 21]. The RE-CIRCUIT [22], VENTURE-AF [23] and AXAFA [24] trials have respectively demonstrated the safety and efficacy of uninterrupted dabigatran, rivaroxaban, and apixaban during catheter ablation of AF. However, patients with HCM were not represented in these trials. Data on catheter ablation of AF in HCM patients are still sparse, and only arising from small observational studies [1]. A systematic review and metanalysis from our group has shown that catheter ablation of AF appears to be safe in the HCM population, and might represent a valuable option despite a higher arrhythmia relapse rate compared to the general population [1].
To the best of our knowledge, we present the largest published series of HCM patients undergoing catheter ablation of AF, and this is the first study to investigate the effectiveness of NOACs in this high-risk setting. We are not aware of other studies where NOACs have been used at the time of AF ablation in individuals with HCM.
Our findings are reassuring and add to the body of evidence suggesting that use of NOACs appears to be safe and effective in HCM patients with AF, with a risk profile which appears at least similar to VKAs. Of note, no intracardiac thrombus was identified in the 40 pre-procedural TOEs in the NOAC group. Similarly, there were no embolic events in the NOAC group and major bleeding and cardiac tamponade were numerically lower compared to VKA. We believe our findings might have relevant clinical implications in HCM patients with AF elected for an ablative strategy as they ease some of the concerns regarding NOACs and the absence of data in this high-risk setting.