Background: Asian patients on warfarin therapy usually have lower international normalized ratio (INR) intensities than those recommended by Western clinical practice guidelines. This study evaluated whether a high INR reduces the incidence of thromboembolism (TE) or bleeding events in Asian patients with high CHA2DS2-VASc scores after valve surgery.Methods and Results:Data of adult patients after valve surgery were retrieved from an integrated healthcare information system of a single hospital between 2014 and 2016. The INR was derived from the closest laboratory data before the index outpatient-clinic visit date. The endpoint of every record was determined as emergency room visit or hospitalization because of TE or bleeding event. A total of 37 TE or bleeding events were retrieved from 8,207 records; the annual incidence rate were 1.2% and 2.8% for low (0-2) and high (3-8) CHA2DS2-VASc score groups, respectively (P=0.007). The incidence rates were lowest for both groups at an INR of 1.5-2.0. High INR intensities did not reduce TE or bleeding incidence. INR >3.0 was associated with increased TE or bleeding incidence in the high-score group (6.8%/year vs. 2.0%/year, P=0.079).
Conclusions: The optimal INR is 1.5-2.5 for low- or high-score Asian patients after valve surgery. INR >3.0 was associated with increased TE or bleeding incidence in the high-score group.
Keywords: Anticoagulation; Chinese; Follow-up study; Valve surgery; Warfarin.