Antiplatelet therapy early after bioprosthetic aortic valve replacement is unnecessary in patients without thromboembolic risk factors.

Background: The use of antithrombotic therapy during the postoperative period after biological aortic valve replacement (AVR) in patients without thromboembolic risk factors remains controversial. Treatment with warfarin is recommended for the first 3 months after biological AVR. The use of antiplatelet therapy - mainly aspirin (ASA) - is suggested as an alternative treatment but its efficacy is still unsettled. Due to the increased risk of bleeding complications even no use of any antithrombotic or antiplatelet therapy was advocated. Given this ongoing dispute, the aim of this retrospective double-institutional study was to evaluate the necessity of antiplatelet treatment by ASA with no postoperative antiplatelet therapy in terms of survival, major bleedings and cerebral thromboembolism of patients undergoing biological AVR without thromboembolic risk factors.

Methods: From January 2001 to December 2003, 288 consecutive patients (72.8+/-7.5 years, 134 males) with sinus rhythm and no other thromboembolic risk factors underwent single biological AVR with porcine or bovine pericardial valves without concurrent coronary artery bypass graft surgery. By surgeons preference, 100 mg ASA was given to 132 patients, and 156 patients received no antiplatelet therapy. Patients were followed for cerebral ischemic events, major bleedings, need for repeat operation, NYHA class and survival at three time intervals postoperatively (30 days, 3 and 12 months).

Results: None of all patients died during the operation. Mortality within 30 days was 3.8% in the ASA and 3.9% in the no ASA group (p=0.777). There were no statistically significant differences for cerebral ischemia within 3 months after AVR (ASA 0.8% vs no ASA 1.3%: p=0.884) and 3 to 12 months after AVR (ASA 0.8% vs no ASA 0%; p=0.933). Major bleedings occurred in two ASA-treated patients and in one patient without antiplatelet therapy (p=0.884). The incidence of NYHA class III-IV after 3 months (1.5% vs 1.9%; p=0.850) and 12 months (9.0% vs 5.1%; p=0.278) were similar, as were the need for repeat operative AVR after 12 months (0.8% vs 0.6%; p=0.553). Survival rates at 12-month follow-up were 95.5% for ASA treatment and 94.9% for no ASA treatment (p=0.963).

Conclusions: In patients without thromboembolic risk factors undergoing biological AVR administration of ASA confers no advantage compared to no antiplatelet therapy. Functional status, thromboembolic events and survival were not adversely affected by withholding any antiplatelet therapy. Guidelines need to be reviewed for the antithrombotic therapy of patients without risk factors undergoing bioprosthetic AVR.