OBJECTIVE

Self-testing to determine the international normalized ratio improves management with warfarin and reduces the risks of adverse events. Self-testing usually begins several weeks after hospital dismissal after valve replacement. We aimed to compare the in-hospital initiation of international normalized ratio self-testing with usual care in mechanical heart valve recipients.

METHODS

A total of 200 adult mechanical heart valve recipients were randomly assigned to in-hospital international normalized ratio self-testing instruction or usual care. Instruction for self-testing patients began on the fourth postoperative day. The patients were followed up for 3 months to compare the number of international normalized ratio tests, percentage of time in the therapeutic range, and adverse events.

RESULTS

The baseline characteristics were similar between the 2 groups. During the first 3 postoperative months, the usual-care group underwent an average of 10 international normalized ratio tests, and the self-testing group completed 14 international normalized ratio tests. The mean ± SD percentage of international normalized ratio tests within the therapeutic range was 45% ± 22% for the usual-care group and 52% ± 22% for the self-testing group (P = .05). Within 90 days after dismissal, transient ischemic attack occurred in 1 patient in the usual-care group and 2 patients in the self-testing group. Bleeding complications occurred in 3 patients in the usual-care group and 5 patients in the self-testing group.

CONCLUSIONS

Management of anticoagulation with warfarin after mechanical valve replacement is improved with self-testing, even during the early postoperative phase when international normalized ratio testing is performed frequently. Although the incidence of adverse events was similar in the 2 groups, better control of the international normalized ratio would be expected to improve outcome in large populations of patients.