In a large retrospective study, adverse events increased if the INR was >4.0 in patients with a mechanical AVR. In patients with a current-generation mechanical AVR with- out other risk factors for thromboembolism, in the group treated to an INR of 2.0 to 3.0, the risk of thromboembolic events was similar to, but the risk of bleeding lower than, those of the group treated to an INR of 3.0 to 4.5 (P<0.01).7 In a ran- domized trial comparing moderate-intensity (INR 2.0 3.0) with high-intensity (INR 3.0 to 4.5) oral anticoagulation in patients with a single mechani- cal valve replacement, there was no difference in embolic events but a reduction in bleeding with the moderate-intensity group.8 In a study com- paring an INR target of 1.5 to 2.5 with a target of 2.0 to 3.0 in patients with current-generation mechanical aortic prosthetic valves and no other thromboembolic risk factors, the lower INR target range was noninferior, but the quality of the evi- dence was low.6 For current-generation mechani- cal valve prostheses in the aortic position, an INR of 2.5 (range, 2.0 3.0) provides a reasonable bal- ance between the risks of thromboembolism and 3. In patients with an aortic mechanical prosthesis who are at higher risk of thromboembolic com- plications, the INR should be maintained at 3.0 (range, 2.5 3.5). Risk factors include AF, previous thromboembolism, hypercoagulable state, and older-generation prosthesis (eg, ball-in-cage).10 Severe LV dysfunction may also increase throm- 4. The incidence of thromboembolism is higher with mitral than with aortic mechanical valves, and it is lower in mitral mechanical valve patients with a higher rather than a lower INR. 