Low-Dose Warfarin Bests Standard Therapy After Valve Replacement
After On-X mechanical aortic valve replacement (mAVR), bleed risk is significantly improved with lower-intensity warfarin plus aspirin vs the standard dose in high-risk patients, and dual-antiplatelet therapy (DAPT) worsens bleed outcomes in low-risk patients, according to results of the PROACT trial.
Conducted by Dr John D Puskas and colleagues, PROACT (Prospective Randomized On-X Anticoagulation Trial) included 576 patients aged 18 years or older undergoing mAVR at 41 sites in the United States and Canada.
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Three months after mAVR, patients were randomly assigned to either the low-risk arm or the high-risk arm.
Of the 201 patients in the low-risk arm—those with no thromboembolic risk factors at baseline—99 received DAPT (aspirin 325 mg plus clopidogrel 75 mg) and 102 received standard warfarin plus aspirin therapy from June 2006 through February 2014.
Of the 375 patients in the high-risk arm—those with at least 1 thromboembolic risk factor at baseline—185 received lower-intensity warfarin plus aspirin therapy and 190 received standard warfarin plus aspirin therapy from June 2006 through October 2009.
Over a median 8.8-year period, DAPT caused a significant increase in cerebral thromboembolic events in patients in the low-risk arm, which led to termination of treatment. However, the researchers noted no differences in bleeding risk or all-cause mortality.
For patients in the high-risk arm, lower-intensity warfarin plus aspirin therapy significantly reduced major and minor bleeding up to 8.7 years after mAVR, when compared with standard warfarin plus aspirin therapy. No differences were seen in thromboembolism risk or all-cause mortality.
“DAPT was associated with higher rates of thromboembolism and valve thrombosis compared with control in the low-risk arm,” the researchers concluded. “International normalized ratios were safely maintained at 1.5 to 2.0 in high-risk patients, without differences in mortality or thromboembolic complications.”
Puskas JD, Gerdisch M, Nichols D, et al. Anticoagulation and antiplatelet strategies after on-X mechanical aortic valve replacement. J Am Coll Cardiol. 2018;71(24). doi:10.1016/j.jacc.2018.03.535.
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