Effect of low-dose aspirin on the international normalized ratio variability in patients with mechanical heart valve prostheses.

An increased risk of bleeding is associated with a more intense oral anticoagulation, a greater international normalized ratio (INR) variability and the use of aspirin. We studied the INR variability of patients (n = 121) with modern heart valves who had been prospectively randomized to receive acenocoumarol at a targeted INR of 2.4-3.