Choice of echocardiography method for postoperative evaluation of mitral valve replacement with a mechanical...

The French Cardiology Society (SFC) systematically recommends (Class I) transesophageal echocardiography (TEE) after any mitral valve replacement with a mechanical prosthesis (MMVR). Taking into account the increasing workload of echocardiography laboratories, our attitude was to propose that only post-operative transthoracic echocardiography (TTE) is performed. The purpose of this study was to evaluate the possible risks of this simplified procedure.

We performed a precise analysis of one full year of practice of MMVR with exhaustive follow-up for the first 2 years concentrating on thromboembolic complications.

From January to December 2003, 84 MMVRs (46 after rheumatic fever, 22 degenerative disease, 11 infective endocarditis (IE) and 5 ischemia) were conducted in 45 women and 39 men of average age 61 years. Early mortality (<30 days) concerned 5 patients (5.9%). A control TTE to determine normal prosthetic function was performed 7+/-2 days after surgery and this revealed 2 cases of nonobstructive thrombosis which were treated medically, 3 cases of paraprosthetic regurgitation, and 1 vegetation due to underlying IE. Actuarial survival was 90.5% at 1 year and 83.3% at 2 years. After a mean follow-up of 179.3 patient-years, 5 patients were reoperated (5.9%): 1 for IE, 1 for paravalvular regurgitation, 1 for mitral valve insufficiency with haemolysis, and 2 for obstructive prosthetic valve thromboses. In addition there were 2 cases of prosthetic valve thrombosis, 8 ischemic strokes (2 ministrokes, 6 sequelar strokes), and 1 peripheral embolism. The global thromboembolic complication rate was therefore 6.1 per 100 patient-years (n=11). There were 4 hemorrhagic events, i.e. a rate of 2.2 events per 100 patient-years. 63% of the 1193 INR conducted were within the target range (3-4.5), 26% were below 3 and 11% were greater than 4.5. 35% of patients with thromboembolic complications had an INR<3.

Morbidity and mortality during the first 2 years after MMVR were relatively high but equivalent to the values of comparable series in the literature. These complications would not have been reduced by a more precise screening based on early TEE. Despite the increasingly litigious nature of the doctor-patient relationship, it would probably be excessive to oppose that this guideline was not followed in a dispute; in particular as it is difficult to apply this measure as echocardiography departments are overworked.