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Direct oral anticoagulants (DOACs) are getting used off-label with prosthetic heart valves, even mechanical valves in some cases, a national registry showed.

At least some valve patients were discharged with a DOAC prescription at 78.6% 0f the 1,092 hospitals and by 59.6% of the 2,731 physicians participating in the Society of Thoracic Surgeons Adult Cardiac Surgery Database from July 2014 through June 2017.

For mechanical heart valve recipients, the rate was 1.1% with aortic valve replacement and 1.04% with mitral valve replacement, without significant change over time for either, Ankur Kalra, MD, of the Cleveland Clinic, and colleagues reported in .

"I am really very surprised that DOACs are being used in mechanical heart valves," commented Deepak Bhatt, MD, MPH, of Brigham and Women's Hospital Heart & Vascular Center and Harvard Medical School in Boston, who was not involved with the study.

"I suppose there are a few patients where there may just be no other options, but the data to date suggest this is a risky strategy. There are ongoing trials that may provide more definitive data, but so far, the data have suggested a safety concern," he added.

For aortic valve replacement with bioprosthetic heart valves, 4.66% of patients were discharged with a DOAC prescription overall, and that rate did increase over the study period: from 3.30% in 2014 to 6.64% in 2017 (P=0.02 for trend).

For mitral valve replacement with bioprosthetics, the DOAC prescription rate was 5.89% overall and increased from 3.94% in 2014 to 7.72% in 2017 (P=0.03 for trend).

Bhatt suggested that this practice has somewhat better support for safety: "With bioprosthetic valves, at least we have some subgroup data from the atrial fibrillation trials that this practice is reasonably safe," he said.

The researchers agreed on the lack of satisfactory safety data for such prescribing. "Until the completion of randomized clinical trials that provide sufficient evidence for DOAC use, physicians may wish to exercise caution with regard to DOAC prescription for patients with prosthetic heart valves," the team wrote.

Factors significantly associated with use of mechanical valves included preoperative use of factor Xa inhibitors (3.8% vs 0.3% in those discharged on warfarin) and postoperative events before discharge, especially atrial fibrillation or flutter (43.0% vs 22.0%), reoperation for bleeding (9.1% vs 3.0%), and thromboembolic events.

Factors associated with DOAC prescription with bioprosthetic valves included preoperative arrhythmias (54.8% vs 42.0%), preoperative use of factor Xa inhibitors (2.6% vs 0.5%), and thrombin inhibitors (0.5% vs 0.2%). Compared with warfarin patients, they had fewer postoperative events like kidney failure and reoperation for bleeding but more postoperative atrial fibrillation or flutter and thromboembolic events.

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