By Michael H. Crawford, MD, Editor
SYNOPSIS: A study of patients with obstructive prosthetic valve thrombosis that deployed low-dose, slow infusion thrombolysis or surgery using shared decision-making, showed thrombolysis was highly effective and resulted in fewer major complications than surgery.
SOURCE: Özkan M, Gündüz S, Güner A, et al. Thrombolysis or surgery in patients with obstructive mechanical valve thrombosis. J Am Coll Cardiol 2022;79:977-989.
Thrombosis of a mechanical prosthetic heart valve (PVT) is a serious complication usually caused by inadequate anticoagulation. Surgery has been the traditional recommendation in this situation, especially if the valve thrombosis is obstructive. Alternatively, low doses of tissue-type plasminogen activators (tPA) administered slowly might be safe and effective for some patients, but there are no randomized trials. Thus, the optimal treatment of PVT is unclear.
Accordingly, investigators from Turkey shared their experience with these two initial treatments for PVT. They enrolled 276 patients (median age, 49 years; 65% women) who experienced a PVT between 2014 and 2020 and were candidates for either approach. They excluded patients with non-obstructive PVT, contraindications to thrombolysis, cardiogenic shock, or obstructive pannus. Employing shared decision-making, one or the other approach was chosen among these patients in whom PVT was diagnosed and characterized by Doppler echocardiography and pannus or vegetation were excluded. The size of the thrombus or the combined size of all thrombi were recorded.
The final study population of 158 received either a six-hour infusion of 25 mg of tPA, with repeat infusions up to six times or an ultraslow (25-hour) infusion (if needed), or surgery. Echocardiographic surveillance was used between infusions. In patients who met the criteria for success (complete thrombus resolution) or partial success (thrombus < 10 mm), thrombolysis stopped. Subsequently, anticoagulation with heparin and then warfarin started. Surgery involved median sternotomy and either thrombectomy or valve replacement, depending on the findings. The primary endpoint was three-month mortality, and the secondary endpoint was all major complication during the three-month follow-up period.
The initial management technique was thrombolysis in 53% and surgery in 47% (83% valve replacement). The overall success rate of thrombolysis was 90%, with a median tPA dose of 59 mg. The three-month mortality was 2.4% with thrombolysis and 19% with surgery. Major bleeding occurred in 2.4% with thrombolysis and 9.3% with surgery; embolic events were 2.4% and 5.3%, and the rethrombosis rate was 2.4% and 6.7%, respectively. The authors concluded in patients with obstructive mechanical valve thrombosis, low-dose infusions of tPA was more successful, resulted in lower rates of mortality, and led to fewer major complications at three months vs. surgery.
COMMENTARY
In this study, patients experienced much lower rates of bleeding and embolism with thrombolysis, even though this carries the potential for high complication rates. Here, the authors used an approach of shared decision-making. Remarkably, the thrombolysis and the surgery groups were quite similar regarding many clinical characteristics and the number in each group were near equal. The success rate of thrombolysis was 90%, with a mean dose of 59 mg infused. The impressive safety of thrombolysis probably was because of the use of low-dose, slow infusion tPA. The authors administered 25 mg over six to 25 hours, with repeated doses for six hours up to a total of 150 mg, if needed. These doses and infusion rates resulted in far fewer bleeding and embolic complications. Consequently, the complications of surgery were considerably higher. Although major bleeding rates were almost four times higher with surgery, cerebral bleeds were nearly identical and infrequent (1.2% thrombolysis, 1.3% surgery). Interestingly, embolic complications were twice as frequent with surgery (5.3% vs. 2.4% with thrombolysis). Therefore, a low-dose, slow, or ultraslow infusion of tPA should be considered a viable first-line approach to obstructive PVT.
The fact this was an observational rather than randomized trial is a limitation. However, treatment selection was handled through shared decision-making among the heart team and patients. This is a real-world study in an area where a randomized design might be considered unethical. Although the two groups were remarkably similar and all the patients were candidates for both therapies, there were more women in the thrombolysis group, which could have biased the study. Also, the follow-up period was relatively short. Despite these limitations, the authors made a strong case for considering thrombolysis using their protocols to be first-line therapy for obstructive PVT.
A study of patients with obstructive prosthetic valve thrombosis that deployed low-dose, slow infusion thrombolysis or surgery using shared decision-making, showed thrombolysis was highly effective and resulted in fewer major complications than surgery.
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