Risk factors for valve-related complications after mechanical heart valve replacement in 505 patients with long-term follow up

Abstract

Background and aim of the study: Currently, valve thrombosis, thromboembolic events and bleeding events account for 75% of all complications that occur after mechanical heart valve replacement. The study aim was to determine the main risk factors for valve-related complications in patients undergoing mechanical heart valve replacement.

Methods: Data were available from the systematic follow up of patients who had received a CarboMedics bileaflet mechanical heart valve replacement at the authors' institution. Follow up examinations were conducted prospectively at two-year intervals, via questionnaires sent to the patients' general practitioners, or by telephone calls.

Results: Between January 1988 and December 2005, a total of 505 consecutive patients (300 males, 205 females; mean age 52 years; range: 5 to 77 years) underwent heart valve replacement using a CarboMedics mechanical prosthesis. Aortic valve replacement (AVR) was performed in 308 patients, mitral valve replacement (MVR) in 134 patients, and double-valve replacement (DVR) in 62 patients. The follow up was 95.4% complete; the mean follow up was 7.5 years, and the total follow up 3,718 patient-years. Thromboembolic and bleeding complications represented the leading cause of valve-related events (104/195), of valve-related mortality (15/25), and of the need for repeat surgery (9/16). Valve thrombosis occurred in 12 patients. Implantation in the mitral position was identified as a risk factor (HR = 15.07; CI: 8.41-23.07; p 0.0001). Thromboembolism occurred in 32 patients; the use of antiplatelet agents was found to be a protective factor (HR = 0.23; CI: 0.08-0.70; p = 0.01). Bleeding events occurred in 52 patients; risk factors for bleeding events included a history of thromboembolic or bleeding complications (HR = 2.70; CI: 1.33-5.26; p = 0.006) and an unstable International Normalized Ratio (INR) (HR = 2.86; CI: 1.01-8.08; p = 0.05).

Conclusion: After mechanical heart valve replacement, the only risk factors for bleeding complications were an unstable INR and a history of thromboembolic or bleeding events. The use of antiplatelet agents proved to be a protective factor against thromboembolic events.