AATS: Low-dose anticoagulation safe in some valve patients

A less aggressive approach to anticoagulation therapy after implantation of a bileaflet mechanical valve appears to be safe, according to an interim report from the PROACT trial presented May 6 at the annual American Association for Thoracic Surgery (AATS) meeting in Minneapolis.

PROACT (Prospective Randomized On-X Anticoagulation Clinical Trial) was designed to evaluate the safety and effectiveness of an anticoagulation therapy protocol that is less aggressive than current guideline recommendations in patients implanted with the On-X (On-X Life Technologies) aortic mechanical valve. The accepted international normalized ratio (INR) range for a bileaflet mechanical valve in the aortic position is 2 to 3 presently.  

PROACT includes three patient groups: high-risk aortic valve patients randomized to standard anticoagulation therapy compared with an INR of 1.5 to 2; lower-risk selected aortic valve patients randomized to standard anticoagulation therapy or aspirin and clopidogrel (Plavix, Bristol-Myers Squibb); and mitral valve replacement patients randomized to standard therapy or anticoagulation therapy of 2 to 2.5.

In an interim report, John D. Puskas, MD, associate chief of the cardiothoracic surgery division at Emory School of Medicine in Athens, Ga., presented results from the first group of aortic valve replacement (AVR) patients. The study randomized 190 patients to warfarin with a target INR of 2 to 3 plus 81 mg aspirin (the control group) and 185 patients to warfarin with a target INR of 1.5 to 2 plus 81 mg aspirin between 2006 and 2009 (the test group).

All patients were randomized three months after their operations and followed for an average of 3.82 years. There was no significant difference in patient characteristics between the two groups.

Puskas et al found no significant difference in the incidence of stroke, transient ischemic attack or neurological events; mortality; or valve-related events between the groups. Results showed a significant decrease in major and minor bleeding events, though.

“Anticoagulation may be safely reduced in AVR patients after implantation of this approved bileaflet mechanical prosthesis,” Puskas said in a release. “In combination with low-dose aspirin, this therapy resulted in significantly lower risk of bleeding than customary aggressive anticoagulation without significant increase in clots or stroke.”

Puskas presented the results at the meeting’s plenary scientific session. The study was sponsored by On-X Life Technologies, formerly Medical Carbon Research Institute.