Low-dose anticoagulation after isolated mechanical aortic valve replacement with Liva Nova Bicarbon prosthesis: A post hoc analysis of LOWERING-IT Trial

Introduction: Thromboembolic complications are due to a complex interplay between patients’ characteristics, device features and anticoagulation intensity. Subtle design and material differences in available prostheses imply different susceptibility to thrombosis. This post hoc sub analysis of the LOWERING-IT database tested the safety and feasibility of a low-level oral anticoagulant regime in low-risk patients with aortic LivaNova prosthetic valve replacement. Methods: Study population included 148 patients randomized to LOW-INR group, and 144 patients randomized to CONVENTIONAL-INR group. The non inferiority of thromboembolic events between LOW-INR and CONVENTIONAL-INR groups was tested. Results: The two groups were well matched. Cumulative follow-up reached 1,545 patient/years. The mean INR was 1.91 ± 0.23 in the LOW-INR group, and 2.59 ± 0.26 in the CONVENTIONAL-INR group (P<0.001). There were 3 thromboembolic events, all of them in the CONVENTIONAL-INR group. Comparison of thromboembolic events was not significant. The 1-sided 97.5% exact CI for the difference in primary event proportion was 0.54%, satisfying criteria for non inferiority. The incidence of bleeding events was significantly different: 6.61 per 1,000 patient-year in LOW-INR group vs 18.65 per 1,000 patient-year in CONVENTIONAL-INRgroup. Conclusion: Low-dose anticoagulation is safe in selected patients after aortic LivaNova Bicarbon prosthesis implantation.

Thromboembolic complications after cardiac valve replacement are due to a complex interplay between patients' characteristics, device features and anticoagulation intensity. Subtle design and material differences in available prostheses may thrombosis. We conducted a post-hoc sub-analysis of the LOWERING-IT database to test the safety and feasibility of a low-level oral anticoagulant regime in low-risk patients with aortic LivaNova prosthetic valve replacement. The study population included 148 patients randomized to a low INR target (1.5-2.5; LOW-INR group), and 144 patients to the standard INR (2.0-3.0; CONVENTIONAL-INR group). The non-inferiority of thromboembolic events between LOW-INR and CONVENTIONAL-INR groups was tested. Cumulative follow-up reached 1,545 patient/years. The mean INR was 1.91 +/- 0.23 in the LOW-INR group, and 2.59 +/- 0.26 in the CONVENTIONAL-INR group (P < 0.001). There were 3 thromboembolic events, all in the CONVENTIONAL-INR group. Comparison of thromboembolic events was not significant. The 1-sided 97.5% exact CI for the difference in primary event proportion was 0.54%, satisfying criteria non-inferiority. Bleeding events were significantly different: 6.61 per 1,000 patient-year in LOW-INR group vs 18.65 per 1,000 patient-year in CONVENTIONAL-INR group (p < 0.045, RR 0.37). In conclusions these data suggest that low-dose anticoagulation is safe in selected patients after aortic LivaNova Bicarbon prosthesis implantation.