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Hemostatic effects of 1 mg daily warfarin on post CABG patients. Post CABG Studies Investigators
J M Walenga1, D Hoppensteadt, R Pifarré
1Loyola University Medical Center, Maywood, Illinois 60153, USA. jwaleng@luc.edu.
Insights
Low-dose warfarin (1 mg daily) did not alter key blood clotting factors in patients after coronary artery bypass graft surgery. This supports using low-intensity warfarin therapy for managing post-CABG patients.
Area of Science:
- Cardiovascular Medicine
- Pharmacology
- Hematology
Background:
- Coronary artery bypass graft (CABG) surgery improves patient outcomes but carries risks of restenosis and graft occlusion.
- Effective antithrombotic therapy is crucial for long-term success after CABG.
Purpose of the Study:
- To evaluate the hemostatic effects of low-dose warfarin (1 mg daily) in patients who have undergone CABG.
- To assess changes in coagulation parameters and risk factors for thrombosis.
Main Methods:
- A screening study within the Post Coronary Artery Bypass Graft (Post CABG) trial.
- Paired blood samples were collected from stable post-CABG patients (n=40) before and after 21 days of 1 mg daily warfarin.
- Assessed prothrombin time, international normalized ratio (INR), prothrombin fragment 1.2, factor VII, von Willebrand's factor, fibrinogen, tPA, and PAI-1.
Main Results:
- One milligram of daily warfarin did not significantly alter prothrombin time, INR, or prothrombin fragment 1.2.
- No significant changes were observed in hemostatic risk factors including factor VII, von Willebrand's factor, fibrinogen, tPA, or PAI-1.
- These findings indicate minimal impact on coagulation markers with this low warfarin dose.
Conclusions:
- Low-dose warfarin (1 mg daily) appears safe and does not significantly affect key hemostatic markers in stable post-CABG patients.
- This supports the use of low-intensity warfarin therapy (1-4 mg daily, aiming for INR ≤ 2.0) for managing patients after coronary artery revascularization.
Abstract:
Although coronary bypass graft surgery has increased the survival and quality of life of many individuals, patients remain at risk of restenosis and thrombotic occlusion of the coronary arteries and bypass grafts. In the screening period for participation in the multicenter Post Coronary Artery Bypass Graft (Post CABG) trial, the effects of 1 mg daily warfarin were evaluated using paired patient samples collected prior to and after at least 21 days of treatment. In stable patients (n = 40; 39 males 1 female; 51-74 years old) who previously had undergone coronary artery revascularization (1-10 years), no alterations in prothrombin time, international normalized ratio (INR), prothrombin fragment 1.2, or the hemostatic risk factors factor VII antigen and coagulant activity, von Willebrand's factor, fibrinogen, tPA, or PAI-1 were associated with the 1 mg daily warfarin treatment. The observations reported here supported the Post CABG Studies Steering Committee decision to treat patients with 1-4 mg warfarin daily adjusted to achieve INRs not to exceed 2. 0 consistent with low-intensity therapy.