Rate of adverse events during OAT in patients with mechanical prosthetic heart valves replacement

Abstract number: P1944

Poli^* D., Antonucci^* E., Cecchi^* E., Betti^* I., Ilari^* I., Alessandrello Liotta^* A., Mannini^* L., Rogolino^* A., Abbate^* R., Prisco^* D.

^*University of Florence, Italy

Thromboembolic and bleeding complications are major cause of morbidity and mortality in patients with mechanical heart valves. Quality of anti-coagulation levels control is correlated with both type of adverse events. Aim of our study was to evaluate the rate of bleeding and thrombotic complications in patients with mechanical prosthetic heart valves in relation to the intensity of the intended and of the achieved anticoagulation level. From June 1995 to October 2002, we observed 275 consecutive patients (mean age 61.8 ± 1.22 year) followed for a total period of 882 patient-years (pt year^-1) of observation. 241 patients with mechanical prosthetic valves were followed for 842 pt year^-1 and 34 patients with biological prosthetic valves were followed for 40 pt year^-1. 134 patients had aortic mechanical valves (4607 pt year^-1), 72 patients had mitralic mechanical valves (2581 pt year^-1), 35 patients had mitro-aortic mechanical valves (1231 pt year^-1). 25 patients had aortic biological valves (269 pt year^-1), 4 patients had mitralic biological valves (104 pt year^-1), 5 patients had mitro-aortic biological valves (61 pt year^-1). The time spent within, above and below the therapeutic range was 65, 17, and 18% for patients with aortic mechanical valves (INR therapeutic range 25–35) and 56%, 13% and 31% for patients with mitralic mechanical valves (INR therapeutic range 3–4). The differences between the time spent within and below the therapeutic range in the two groups were statistically significant (P < 005) Patients with biological valves (INR therapeutic range 2–3) spent 60, 16, and 23% of the time, respectively, within, above and below the therapeutic range. No adverse hemorragic or thrombotic events were registered in these patients. Patients with mechanical valves in mitralic position had a higher risk of major bleeding complication in relation to patients with mechanic valve in aortic position [RR 41 (09–249) P = 003]. No differences were recorded between the two groups in relation to minor bleeding or thrombotic events. Major bleeding complications occurred more frequently when achieved INR was > 4.5 [RR 16 (36–663) P = 00003]. Major thrombotic complications occurred more frequently when achieved INR was < 2 [RR 72 (08–323) P = 004]. The higher rate of major bleeding complications is recorded in patients with mechanical mitralic valves. This is probably related to the higher intended INR therapeutic range that is associated with a more variable response to oral anticoagulants.