Anticoagulation dilemma in a high-risk patient with On-X valves

Abstract

Thromboembolism continues to be a major concern in patients with mechanical heart valves, especially in those with unsatisfactory anticoagulation levels. The new On-X valve (On-X Life Technologies, Austin, TX, USA) has been reported as having unique structural characteristics that offer lower thrombogenicity to the valve. We report a case where the patient received no or minimal systemic anticoagulation after placement of On-X mitral and aortic valves due to development of severe mucosal arterio-venous malformations yet did not show any evidence of thromboembolism. This case report reinforces the findings of recent studies that lower anticoagulation levels may be acceptable in patients with On-X valves and suggests this valve may be particularly useful in those in whom therapeutic levels of anticoagulation cannot be achieved due to increased risk of bleeding.

Figure 1

Wild fluctuations in platelet count from preoperative visit until discharge on postoperative day 166. Intervals between time points on the x-axis are variable

Figure 2

Patient's international normalized ratio (INR) from preoperative visit until discharge on postoperative day 166, showing subtherapeutic INR at multiple time points throughout the Intensive care unit stay

Figure 3

On-X prosthetic heart valve design and features. (1) Pure carbon, (2) Optimal longer length (3) Inlet flared orifice, (4) Full 90° leaflet opening, (5) Stasis-free pivots, (6) Two-point leaflet closure (with permission from On-X Life Technologies, Inc., Austin, Texas, USA)