The prior recommendation to add low-dose aspi- rin to therapeutic VKA therapy for a mechanical valve prosthesis was based on studies performed decades ago that included many patients with older-generation prostheses who also had addi- tional thromboembolic and vascular risk factors. A 2013 Cochrane Systematic Review showed that compared with anticoagulation alone, the addition of an antiplatelet agent reduced the risk of thromboembolic events and the total mortality rate but at the cost of an increased and offsetting risk of major bleeding.26 The authors pointed out that the quality of the included tri- als tended to be low, possibly reflecting the era when most trials were conducted. An individu- alized approach that takes the risk of bleeding into account is required. 9. In patients without risk factors who receive a mechanical On-X aortic heart valve (On-X Life Technologies Inc., Austin, Texas), targeting the INR to a lower goal (1.5 2.0) in conjunction with aspirin 81 mg daily may be a strategy for long-term management. Warfarin dosing is tar- geted to an INR of 2.5 (range, 2.0 3.0) for the first 3 months after surgery, during which low- dose aspirin is also used.27 This recommenda- tion is based on a single RCT27 of lower- versus standard-intensity VKA therapy (with low-dose aspirin) in patients undergoing On-X AVR. The lower-intensity INR group experienced signifi- cantly less major and minor bleeding, whereas the rates of stroke, transient ischemic attack, total neurological events, and all-cause mortal- ity were similar between the 2 groups. 