High prevalence of hypercoagulable states in patients with recurrent thrombosis of mechanical heart valves

Background and aims of the study: Thrombosis is one of the most feared and life-threatening complications of mechanical heart valves (MHV), with an incidence of 1-3 per 100 patient-years. Hypercoagulable states are highly prevalent in the general population and can predispose MHV to thrombus formation. Thus, we conducted a study to investigate the frequency of hypercoagulable states in patients with MHV who had recurrent thrombosis at least twice after valve implantation. Methods: Fifteen patients (mean age 42 ± 11 years; range: 18 to 55 years) with recurrent thrombosis of MHV (2.4 ± 0.8 recurrences/patient) (group 1) and 15 matched patients (mean age 40 ± 12 years; range: 18 to 55 years) with MHV without thrombosis (group 2) were followed up with transthoracic and transesophageal echocardiography. Patients' sera were monitored for antibodies to cardiolipin (ACLA-IgG and ACLA-IgM), phosphatidylserine (APSA), lupus-type anticoagulant (LA) and lipoprotein(a) (LP(a)). Results: Average values for group 1 versus group 2 were: ACLA-IgG (normal range <15 GPLU/ml) 24.7 ± 14.6 versus 6.2 ± 2.7 (p<0.001); ACLA-IgM (<12.5 MPLU/ml) 7.9 ± 5.0 versus 3.3 ± 1.7 (u = 185; p<0.001); APSA (<12 RLU/ml) 4.8 ± 5.7 and 2.9 ± 1.2 (p = 0.56); and LP(a) (<30 mg/dl) 36.5 ± 26.5 and 13.4 ± 7.1 (p<0.001). The frequency of LA- positive cases was 4/15 in group 1 and 0/15 in group 2 (p>0.05). The frequency of abnormally high levels of ACLA-IgG was 9/15 in group 1 and 0/15 in group 2 (p<0.001); of ACLA-IgM, 2/15 in group 1 and 0/15 in group 2 (p>0.05); of APSA, 1/15 in group 1 and 0/15 in group 2 (p>0.05); and of LP(a), 5/15 in group 1 and 0/15 in group 2 (p<0.05). At least one of the factors included in this study was abnormal in 14 of 15 (93%) patients (p<0.0001). Conclusions: Hypercoagulable states are highly prevalent in patients with recurrent thrombosis of MHV. All patients evaluated for therapy of obstructive thrombosis of MHV should be investigated for hypercoagulable state. Moreover, in high-risk patients, surgical replacement of the MHV with a bioprosthesis should be considered.