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.