The low rate of thromboembolic complications and major bleeding seen with dabigatran (which was also similar to that observed with warfarin) seems to provide favourable support for its use, as an alternative to warfarin, in the setting of catheter ablation of AF. These results add important information on the use of dabigatran in this setting. They also serve to potentially alleviate some of the concerns raised by the rather unfavourable results in earlier studies (2.1% stroke or TIA and 6.2% major bleeds),9
suggesting that dabigatran significantly increased the risk of bleeding or thromboembolic complications compared with uninterrupted warfarin therapy.
A very low rate of stroke and thromboembolic events was found in this meta-analysis among patients treated with dabigatran (0.55%), similar to what has been found in a recent analysis of Medicare beneficiaries (0.6–0.9%).28
A lower, but not significantly different, prevalence of embolism was found in the warfarin arm of this meta-analysis (0.17%), composed mainly of patients with uninterrupted treatment. This value is similar to the one described by Hussein et al29
in patients with uninterrupted warfarin. Therefore, we think that despite showing similar results compared to warfarin in this meta-analysis (and presenting values for thromboembolic complications similar to what has been reported in large registries of patients using anti-vitamin K agents28
), validation of these results in future randomised controlled trials with blinded analysis may be justified. Furthermore, the use of uninterrupted dabigatran may also merit assessment, taking into account the promising results of the recently available study with this treatment regimen.19
The proportion of patients referred for AF ablation who are on longstanding dabigatran therapy is progressively increasing. This is likely to pose new challenges for the practising cardiologist, including the question of performing the procedure without discontinuation of dabigatran. The pooled data in this study from a large sample of patients provides an opportunity to address some of these issues.
In this meta-analysis comprising 14 controlled trials, dabigatran performed similarly to warfarin with regard to major bleeding and thromboembolism. Moreover, no deaths were observed in any of the treatment strategies. These results are in agreement with the favourable profile that was observed in an early observational non-controlled trial by Winckle et al.30
Furthermore, a recent analysis of the US Food and Drug Administration (FDA) Mini-Sentinel database for the period from 19 October 2010 (the date of dabigatran approval) to 31 December 2011, found that bleeding rates associated with dabigatran use during the period of interest did not appear to be higher than those associated with warfarin.31
Though the present analysis suggests a lower rate of minor bleeding with dabigatran, there were pronounced differences in the reporting of this end point across the different studies. Furthermore, on sensitivity analysis these results did not remain significant. Thus, while this result needs to be interpreted with caution, it seems, that at the very least, dabigatran is unlikely to be inferior to warfarin in this regard.
No significant differences in major bleeding and thromboembolism were observed between the two assigned dabigatran dosages. However, the low number of patients in each group (resulting from under-reporting of the dosage used in most selected studies), and the low rate of observed events, limit the extent to which firm conclusions can be drawn. The suggestion of less frequent minor bleeding with the 150 mg twice daily dosage is hard to interpret due to the differences in reporting of this end point and in sample size.
The various transition regimens used in patients treated with dabigatran, and the low number of observed events in each of those, renders difficult the task of establishing an ideal transition regimen in this setting. However, the great inter- and sometimes intra-study variability notwithstanding, certain factors are likely to be important for decision making.
The timing for drug interruption before the procedure must take into account the patient's renal function, as 80% of the drug is excreted by this pathway.
In patients with normal renal clearance, the best option may be drug suspension on the morning of the procedure, or the night before, but always <24 h before the procedure.
If renal function is compromised, the drug should probably be interrupted sooner, depending on the degree of renal dysfunction.
There may be a rationale for restarting dabigatran 3–4 h after assuring haemostasis, considering its short half-life and rapid onset of action.
The target ACT during catheter ablation in patients treated with dabigatran should be between 300–350 s (similar to warfarin), as no additional benefits were found for higher values.
Finally, as there seems to be no inherent advantage of any of the studied dabigatran dosages, the creatinine clearance and bleeding risk (HAS-BLED score) should be taken into account for deciding the dosage to be used.