Dabigatran is increasingly used for stroke prevention in patients with atrial fibrillation. Although the drug is effective, ‘friendly’ to use (no routine monitoring required), and associated with a more predictable dose-response relationship, some controversies about its safety have emerged over the last years due to the lack of specific antidote available in case of massive bleeding.
An increasing number of registries have been developed with the aim to assess ‘real-life’ safety and efficacy of dabigatran. The Dresden NOAC Registry is a large prospective registry developed in the administrative district of Dresden, Germany, that has already been used in different publications. In this retrospective study, the authors used the Dresden registry to evaluate the management and outcome associated with two different dabigatran doses in patients with atrial fibrillation. The authors defined the main effectiveness outcome as the annual incidence of thromboembolic complications (stroke, transient ischaemic attack or systemic embolism), while the main safety outcome was the annual incidence of major bleeding events classified using the ISTH definition into major, non-major, and minor bleeding.
Among 341 patients treated with dabigatran between October 1, 2011 and February 28, 2013, 158 patients received dabigatran 150 mg BID, and 183 received dabigatran 110 mg BID. Patients receiving the lower dose were more likely to have heart failure, impaired renal function, despite being at higher thromboembolic risk. Although not statistically significant, the annual incidence of thromboembolic complications was lower in patients receiveing the higher dose (0.9/100 patient-years compared to 2.9/100 patient-years). The incidence of bleeding events was lower in patients that received the lower dabigatran dose (major bleeding: 1.7/100 patient-years vs. 2.8/100 patient-years). Among those who experienced a major bleeding event, 27% required an invasive procedure, 54% received red blood cells transfusion, 9% received fresh frozen plasma, and 18% received prothrombin complex concentrates.
The results of this retrospective analysis are descriptive and only allow for the assessment of the safety and efficacy in a general and heterogeneous populations of patients with atrial fibrillation without adjustment for confounders (e.g. co-morbidities) and control group (e.g. vitamin K antagonists). However, this study indicates that the incidence of bleeding is relatively low and that the discontinuation rate of dabigatran (36.4% during median follow-up of 2 years) in daily care patients is driven by non-bleeding side effects rather than bleeding or thromboembolic complications.
– David Faraoni