The importance of international normalized ratio monitoring in patients with mechanical pulmonary valve prosthesis

Background: The most challenging risk of mechanical valves is thromboembolic events; therefore, life-long anticoagulation therapy is necessary. Anticoagulation therapy should be adjusted for each patient with serial INR monitoring. Due to the small number of patients with a mechanical valve in the pulmonary position, we are facing a lack of information about the therapeutic range of the INR in these patients so we aimed to specify the INR range which valve malfunction happened and suggest practitioners keep INR above that level. Methods: In this retrospective study, 71 patients who had previously undergone pulmonary valve replacement (PVR) and presented to ShahidRajaie Cardiovascular Medical and Research center with a diagnosis of pulmonary valve malfunction between 2014 and 2021were included. Patients' INR and echocardiographic data at the time of the malfunction as well as three months before the malfunction diagnosis were gathered from the hospital's registry. All data were analyzed using SPSS and Excel software. Results: In this cross-sectional study, 71 patients with mechanical pulmonary valve malfunction were included. 49.3% were male, 50.7% were female, and the mean age of total patients was 33.23 (±8.279). Fifty-one patients had St.Jude Medical valve, 13 patients had CarboMedics valve, and seven patients had On-X valve. The mean INR of all patients three months before malfunction and at the time of malfunction was 2.29 (±0.753)and 2.20 (±0.704), respectively. Conclusions: In this study, most of our patients had INR below the therapeutic range, both at the time of malfunction (81%) and three months prior to it (80%). These results mainly show patients' poor adherence to anticoagulant therapy. Preventive measures should be taken as soon as possible to decrease the possibility of clot formation and valve malfunction.