All foreign bodies inserted in the circulatory system are thrombogenic and require temporary or lifelong antithrombotic therapies to prevent thrombosis. The adequate level of anticoagulation during the first few months determines the long-term durability, particularly for mechanical prostheses, and also for biological valves. Suboptimal anticoagulation is the most frequent source of mechanical valve thrombosis (MVT). The patient's clinical presentation decides how mechanical prosthetic valve obstruction is managed. If the mechanical valve thrombosis is obstructive and the patient is in a critical condition with hemodynamic instability, an immediate surgical intervention should be performed. The thrombolytic treatment is an option for left mechanical valve thrombosis in patients who have high surgical risk and no contraindications and also for right heart valve thrombosis. In non-obstructive thrombosis on the mechanical valve, patients can be asymptomatic, requiring optimization of the anticoagulant treatment. Both obstructive and non-obstructive thrombus formed on the mechanical prosthesis can result in embolic events. If the thrombus persists following anticoagulant treatment, the recommended options include thrombolytic treatment or redo surgery. Pannus can also cause obstruction of the prosthesis for which surgical treatment is the only option. While these clinical scenarios may initially appear to have straightforward solutions in terms of surgery, thrombolysis, or effective anticoagulation, real-world clinical experience often proves more complex. For instance, a patient with some usual comorbidities and non-obstructive mechanical valve thrombosis, experiencing symptoms solely by repeated systemic embolizations, might undergo all three therapeutic options due to the unpredictable nature of MVT. Therefore, treatment indications can intersect both on the time axis and depending on the patient's clinical status and the expertise of the center where he is hospitalized. Moreover, the European and American guidelines show subtle but important differences. The aim of this review was to compare these differences, comment on recent studies and evidence gaps, propose a more pragmatic algorithm combining all current recommendations, and highlight important research directions for this disease that has dominated the cardiovascular landscape for more than five decades, but for which there have been no significant recent changes in management.

Patients with prosthetic cardiac valves are at high risk for thromboembolic complications and need life long anticoagulation with warfarin, which can be associated with variable dose requirements and fluctuating level of systemic anticoagulation and may predispose to thromboembolic and or hemorrhagic complications. Prosthetic cardiac valve thrombosis is associated with high morbidity and mortality. A high index of suspicion is essential for prompt diagnosis. Transthoracic echocardiography, and if required transesophageal echocardiography are the main diagnostic imaging modalities. Medically stable patients can be managed with thrombolytic therapy and anticoagulation, while some patients may require surgical thrombectomy or valve replacement. We present a case report of a patient with prosthetic mitral valve and an unusually large left atrial thrombus with both thromboembolic and hemorrhagic complications.

Mechanical prosthetic valve thrombosis (PVT) is a potentially life threatening event that occurs with an incidence of 0.2% per patient year following aortic valve replacement [Lengyel M, Fuster V, Keltal M, et al. Guidelines for management of left-sided prosthetic valve thrombosis: a role for thrombolytic therapy. J Am Coll Cardiol 1997;30:1521-6]. We present the case of a middle-aged man with thrombosis of his aortic valve prosthesis mimicking an acute coronary syndrome. The patient received thrombolytic therapy with subsequent embolism of thrombotic debris to the leg.

Prosthetic valve thrombosis is a rare and dreaded complication of patients with mechanical valves, particularly those in the mitral position. A 45-year-old female with status post prosthetic mitral valve replacement was admitted to the hospital with acute pulmonary edema. Echocardiography showed mitral valve thrombosis which was treated with tissue plasminogen activator (t-PA). During t-PA infusion she developed acute inferoposterior myocardial infarction. Coronary angiography showed normal coronary arteries. Presented case had acute inferoposterior myocardial infarction secondary to coronary emboli after the successful thrombolytic treatment of prosthetic mitral valve thrombosis.

In carefully selected patients with stuck mitral valves, thrombolytic therapy is becoming an established therapeutic modality. However, the management of patient with a suboptimal response to an initial thrombolytic course is unclear. The objective was to evaluate the efficacy and safety of re-administration of tissue-type plasminogen activator (rt-PA) in patients with stuck mitral valves in whom the first thrombolytic course has failed to restore normal prosthetic valve function. The study group included patients who received rt-PA and did achieve a full restoration of valve function after the initial course. Data were gathered on the safety and success rates of additional thrombolytic courses in the same hospitalization period, and their predictors. Twelve patients with stuck mitral valves experienced a total of 13 episodes in which a full resolution of leaflet abnormality was not achieved after the initial thrombolytic course. A repeated thrombolytic course was attempted in 10 patients (11 episodes). Six patients (60%) showed full success rate with repeated thrombolysis, one (10%) showed partial success, and three patients (30%) had no improvement following the second course. These last three were those with initial failure. Age, gender, valve model, worst functional class, time since valve implantation and International Normalized Ratio (INR) levels were similar in both groups. No major adverse events were noted. In this small group of patients with stuck mitral valves, re-administration of rt-PA after a partial response to an initial thrombolytic course was effective and safe. However, total failure of the first thrombolytic course predicted inefficiency of further courses.