Characteristics of Atrial Fibrillation Patients Not Switched from Vka to Noac and Persistence on Vka – a Subgroup Analysis of the Prospective Dresden Noac Registry (NCT01588119)

Background and Objective: Currently, non-VKA oral anticoagulants (NOAC) are replacing vitamin-K antagonists (VKA) in stroke prevention in atrial fibrillation (SPAF). We evaluated characteristics of SPAF patients that are not switched from VKA to NOACs in daily care.

Methods: The prospective Dresden NOAC registry stopped enrolment of dabigatran and rivaroxaban patients on February 28, 2013. At that day, participating sites were asked to enrol all VKA patients seen for regular INR testing who remained on VKA and for whom switching to NOAC was not anticipated. VKA patients were followed for one year.

Results: In total, 50 physicians registered both SPAF patients on NOAC-therapy (n=709) and on VKA therapy (n=427; table 1). Compared to the NOAC registry cohort, patients that continued VKA therapy more often were male and less often had a history of TIA/stroke, unstable INR values or a history of bleeding complications compared to the NOAC cohort. The mean duration of VKA pre-treatment was 70.7 months (range 1–432 months). For 328 of the 427 VKA patients (62%), the INR documentation was available for at least 6 months backwards and mean TTR (calculated according to Roosendaal) was 72.2% (SD 19.6). Enrolling sites indicated “stable INR” (95.3%), “costs” (6.3%) and “contraindication for NOAC” (2.3%) as the most common reasons to continue with VKA therapy in these patients.

As of June 30^th 2014, completed FU correlated to 472.42 patient years. At 12 months-FU (completed in 330 pts.), 311 patients (94.2%) were still taking VKA, 13 patients (3.9%) were switched to other anticoagulants and the remaining 6 patients (1.8%) stopped taking anticoagulants completely. Most common reasons for VKA discontinuation were bleeding complications (7/19; 36.8%) and unstable INR (6/19; 31.6%).

Conclusion: NOAC-experienced physicians keep around 40% of anticoagulated SPAF patients on VKA, mostly due to the fact INR is considered to be stable or NOAC to be expensive. The mean TTR of 72% indicates that subjective assessment of INR stability is accurate. Patients with a history of stroke or bleeding complications are more likely to be switched from VKA to NOAC. During the following 12 months, less than 6% of the VKA continuers need to stop VKA treatment, indicating that the subjective assessment of the attending physician identifies patients with acceptable VKA treatment persistence.