Registry data charting the use of direct oral anticoagulants (DOACs) in patients receiving mechanical and bioprosthetic heart valves suggests that despite being contraindicated and off-label, respectively, there is a prevailing use of DOACs among these patients.
The findings, gained from analysis of the Society of Thoracic Surgeons (STS) National Database, were presented by Ankur Kalra (Associate Professor, & Director of Research for Regional Cardiovascular Medicine, Cleveland Clinic, Cleveland, USA) during a late-breaking trial session focused on valve and structural heart disease at the 2021 Cardiovascular Research Technologies meeting (CRT 21 Virtual, 13 February–24 April). They have also been published as a research letter online in JAMA Network Open.
Kalra’s data pointed to a significant increase in the trend of off-label DOAC use among patients with bioprosthetic heart valves—in both aortic and mitral replacement—from 2014–2017, while at the same time suggesting that DOAC-use among mechanical heart valve patients has been constant.
During his presentation, Kalra said that the study sought to establish the current state of the use of DOACs in patients with surgical prosthetic heart valves in the USA, with an objective to evaluate differences in preoperative and postoperative profiles among patients who received DOACs versus warfarin.
He commented that presently there is only one clinical trial to compare DOACs in mechanical valve patients—RE-ALIGN, results of which were published in The New England Journal of Medicine in 2013. “[RE-ALIGN] actually reported harm with dabigatran in patients with mechanical valves,” Kalra explained, adding: “Not only was there an increase in thrombotic events but also in bleeding events.”
US Food and Drug Administration (FDA) labelling for DOACs contraindicates their use in patients with mechanical valves, whilst their use in patients with bioprosthetic valves is off-label, Kalra said.
To understand their current usage, Kalra and colleagues extracted data from version 2.81 of the STS database, tracking patients who underwent surgical aortic or mitral valve replacement, with either mechanical or bioprosthetic valves, between 2014‒2017.
Detailing usage at discharge, Kalra noted that around 1.1% of aortic mechanical valve patients received DOACs, compared with 1.04% of mitral mechanical valve patients, 4.66% of aortic bioprosthetic valve patients, and 5.89% in those with mitral bioprosthetic vavles. Analysis of trends in DOAC-use among these patients showed an increasing trend in prescriptions of these agents for bioprosthetic valves, whereas in mechanical valves it stayed at around the 1% mark.
Outlining some of the factors that led to the prescription of these agents, Kalra said that older patients were discharged on DOACs compared with warfarin among those with bioprosthetic valves, whilst the same was also true, and statistically significant, for the mechanical valve patients.
Turning to the preoperative characteristics for patients, he explained that hypertensive patients, patients with arrhythmias, and patients with vascular disease in the mechanical valve group were more likely to be discharged on a DOAC compared with warfarin. For the bioprosthetic valves, he noted that patients with more comorbidities were discharged on DOACs compared with warfarin.
Noting that the findings are somewhat limited by the lack of follow-up data to compare outcomes of DOACs versus warfarin in patients with prosthetic valves, he summarised that the study points to a prevailing off-label use of DOACs in patients with prosthetic heart valves.
He concluded: “Until the completion of randomised clinical trials that provide sufficient evidence for DOAC use, physicians may wish to exercise caution with regard to DOAC prescription in patients with prosthetic valves.”