According to findings published in JAMA Network Open, a lower international normalized ratio (INR) range may not be associated with increased risk of thromboembolic events in Asian populations after mechanical valve replacement.
The investigators conducted a retrospective cohort study to evaluate the association between INR and anticoagulation-related outcomes in an Asian population after mechanical aortic valve replacement (AVR) or mitral valve replacement (MVR).
The investigators used electronic medical records from the Chang Gung Research Database of patients who underwent AVR, MVR, or combined AVR-MVR at 3 medical centers and 4 regional hospitals between 2001 and 2018.
The primary outcomes were a composite bleeding event (hemorrhagic stroke, gastrointestinal bleeding, genitourinary bleeding, and major bleeding) and a composite thromboembolic event (ischemic stroke, acute myocardial infarction, systemic thromboembolism, or bowel ischemia). The outcomes were recorded 1 day before through 7 days after the date of each INR examination, and all patients had at least 2 INR examinations after discharge. The researchers used a logistic regression model, considering the INR a restricted cubic spline (RCS) variable, to evaluate possibility of nonlinearity and cutoff potential for the INR.
The study included 900 patients (58.3% male and 41.7% female) with a mean age of 52.0 years. Among the patients, 52.7% had AVR alone, 36.6% had MVR alone, and 10.8% received combined AVR-MVR.
With the RCS model, the investigators found the AVR group had higher risk of composite thromboembolic events associated with an INR of <2.0 or >2.6 vs an INR of 2.0, and a higher risk of bleeding events was associated with an INR of <1.8 or >2.4 vs an INR of 2.0.
When the team treated the INR as a categorical variable in the model, the risks of composite thromboembolic and composite bleeding events were significantly higher among patients with INRs < 1.5 (adjusted odds ratio [aOR], 2.55; 95% CI, 1.37-4.73) and with INRs of ≥3.0 (aOR, 3.48; 95% CI, 1.95-6.23) than those with INRs between 2.0 and 2.5.
When the investigators assessed the MVR and combined AVR-MVR groups with the RCS model, higher risks of composite thromboembolic events were associated with an INR of <2.1 or >2.7 vs an INR of 2.5, and a higher risk of bleeding events was associated with an INR of <2.1 or >2.8 vs an INR of 2.5. When the team treated the INR as a categorical variable, the risk of a composite bleeding events was significantly higher among patients with INRs of ≥3.5 (aOR, 2.25; 95% CI, 1.35-3.76) than those with INRs between 2.5 and 3.0.
“In this study, the incidence of thromboembolic events among patients in the MVR group with INRs in the range of 2.0 to 2.5 was not significantly higher than that among those with INRs in the 2.5 to 3.0 range; in the AVR group, the incidence of thromboembolic events among patients with INRs in 1.5 to 2.0 range was not significantly higher than that among those with INRs in the 2.0 to 2.5 range,” the investigators wrote in their report. “Further randomized clinical trials are warranted to develop a therapeutic recommendation for the Asian population.”
Limitations of the study included the retrospective design and potential coding errors and inconsistencies in identifying bleeding and thromboembolic events.
Huang JT, Chan YH, Wu VC, et al. Analysis of anticoagulation therapy and anticoagulation-related outcomes among Asian patients after mechanical valve replacement. JAMA Netw Open. 2022;5(2):e2146026. doi:10.1001/jamanetworkopen.2021.46026