From the Guidelines
Postoperative orders for aortic valve replacement should prioritize antithrombotic therapy, with low-dose aspirin favored as an alternative to postoperative anticoagulant therapy for bioprosthetic valves, as recommended by the 2021 guideline from the American Heart Association/American Stroke Association 1. The management of patients after aortic valve replacement requires careful consideration of antithrombotic therapy to prevent thromboembolic complications.
- The use of low-dose aspirin is now favored as an alternative to postoperative anticoagulant therapy for bioprosthetic valves, although this relies on low-level evidence 1.
- When postoperative anticoagulant therapy is indicated, oral anticoagulation should be started during the first postoperative days, with intravenous unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) used to achieve rapid anticoagulation 1.
- The first postoperative month is a high-risk period for thromboembolism, and the addition of aspirin to anticoagulant therapy decreases postoperative thromboembolic risk but increases bleeding risk and cannot be recommended routinely 1.
- For patients with bioprosthetic mitral or aortic valve replacement surgery, oral anticoagulation with warfarin to achieve a target INR of 2.5 (range, 2.0–3.0) is reasonable for at least 3 months and for as long as 6 months after surgery in patients at low risk of bleeding, as recommended by the 2021 guideline from the American Heart Association/American Stroke Association 1.
- After 3 to 6 months after surgery, long-term therapy with only aspirin 75 to 100 mg daily is recommended for patients with bioprosthetic valves 1. In addition to antithrombotic therapy, postoperative orders for aortic valve replacement should include:
- Close hemodynamic monitoring in the ICU with continuous cardiac monitoring, hourly vital signs, and strict intake/output measurements.
- Maintenance of mean arterial pressure between 65-80 mmHg using vasopressors (norepinephrine 0.01-0.3 mcg/kg/min) or vasodilators (nitroglycerin 5-100 mcg/min) as needed.
- Administration of prophylactic antibiotics such as cefazolin 2g IV every 8 hours for 48 hours.
- Pain management with scheduled acetaminophen 1g IV/PO every 6 hours and opioids as needed (hydromorphone 0.2-0.4mg IV every 2-4 hours).
- Maintenance of euvolemia with IV fluids (typically normal saline at 75-100 mL/hr) and diuretics (furosemide 20-40mg IV) as needed.
- Initiation of deep vein thrombosis prophylaxis with sequential compression devices and heparin 5000 units subcutaneously three times daily once hemostasis is achieved.
- Early mobilization within 24 hours post-surgery, and respiratory therapy with incentive spirometry every hour while awake to prevent atelectasis.
From the Research
Postoperative Orders for Aortic Valve Replacement
Anticoagulation Therapy
- The American College of Chest Physicians recommends anticoagulation with Warfarin at an INR range of 2-3 for patients with a bileaflet mechanical valve in the aortic position 2.
- For patients with a mechanical valve and a history of systemic embolization, an INR of 2.5-3.5 combined with low-dose aspirin (80-100 mg) is recommended 2.
- A study suggests that warfarin targeted at an INR of 1.8 (range 1.5-2.0) plus aspirin is safe and effective in patients with an On-X aortic mechanical valve 3.
- Another study found that combined low-dose aspirin and warfarin therapy was associated with a greater reduction in thromboembolism events than warfarin therapy alone after mechanical valve replacement 4.
Aspirin Therapy
- Low-dose aspirin (75-100 mg) is often used in combination with warfarin for anticoagulation therapy after aortic valve replacement 3, 4.
- A study compared aspirin versus warfarin after transcatheter aortic valve replacement in low-risk patients and found no difference in clinical outcomes or valve hemodynamics at 24 months 5.
INR Goals
- The optimal INR goal for patients with a mechanical aortic valve is still debated, but a range of 2-3 is commonly recommended for low-risk patients 6.
- For high-risk patients, an INR range of 2.5-3.5 may be considered, except for On-X valve recipients who may be managed at an INR range of 1.5-2.5 with low-dose aspirin 6.