Management of prosthetic valve thrombosis.

Prosthetic valve thrombosis (PVT) is a life-threatening disease, the treatment strategies for which remain controversial. Transesophageal echocardiography (TEE) is the diagnostic technique of choice. Prosthetic valve obstruction is defined as limited leaflet motion; obstructive and non-obstructive PVT are separated by abnormal or normal leaflet motion. TEE is limited in differentiating thrombus from pannus ('tissue ingrowth'), and sterile thrombi from infected vegetations. Clinical aspects are helpful. The estimated incidence of PVT is 2-4% per year based on autopsy and surgical findings. The true incidence should be higher, as TEE reveals almost as many obstructive as non-obstructive PVT, of which 50% are asymptomatic. The prevalence of asymptomatic non-obstructive PVT in the early postoperative period may reach 10%. Three therapeutic approaches are available for PVT. Surgical mortality may reach 69%, depending on NYHA class and need for emergency surgery. Thrombolysis represents an alternative to surgery, with 84% success and low complication rates (stroke 9%, mortality 5%). In non-obstructive PVT patients in NYHA class I or II, thrombolysis success was higher (92%), without severe complications. No other clinical predictor of success could be confirmed. Besides classical contraindications there are no absolute contraindications (large thrombi, pregnancy, early postoperative period) for thrombolysis. Long-term streptokinase protocols have been used with regular TEE monitoring. Heparin may be an initial treatment for non-obstructive PVT, but thrombolysis is superior in this subset. If thrombi are > 5 mm in size, heparin therapy is unsuccessful and unsafe. TEE monitoring is mandatory during heparin treatment, as thrombi may increase in size and become obstructive. Thrombolysis is recommended as first-line treatment if there are no contraindications. Heparin may be used initially for small non-obstructive thrombi, particularly if thrombolysis is contraindicated. Surgery should be reserved for patients in whom thrombolysis is either contraindicated or has been ineffective, independent of NYHA class.