Passive surveillance of heart valve devices: Björk-Shiley outlet strut fracture rates

The Björk-Shiley Convexo-Concave heart valve has a mechanical failure mode called outlet strut fracture (OSF). Previous analyses have found that the hazard function for OSF is constant over time. This article uses the valve manufacturers implant database to examine the shape of the hazard function over time, employing a previously developed model to impute patient survival times. Decisions about patient management (e.g., elective explant) are based on projecting this risk into the future. An analysis that incorporates the decrement of patients at risk due to death and explant provides estimates of the actual occurrences of OSF over calendar time.