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Interact CardioVasc Thorac Surg 2007;6:806-811. doi:10.1510/icvts.2007.165399 © 2007 European Association of Cardio-Thoracic Surgery
Is thrombolysis or surgery the best option for acute prosthetic valve thrombosis?Department of Cardiology and Cardiothoracic Surgery, James Cook University Hospital, Middlesbrough, UK Received 18 August 2007; received in revised form 24 August 2007; accepted 27 August 2007
*Corresponding author.
A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether the optimal treatment strategy for acute prosthetic valve thrombosis (PVT) is surgical management or thrombolytic therapy. Using the reported search 96 papers were identified. Twelve papers represented the best evidence on the subject, and the author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results and study comments and weaknesses were tabulated for these. Recent AHA/ACC guidelines were also included, as were two large case series of surgical management for comparison. We conclude that the management of obstructive PVT remains widely debated due to a lack of randomised controlled trials. Surgery has been the traditional management of choice, but thrombolysis has recently been proposed as a first-line therapy. Both surgery and thrombolysis can be used with high rates of success and relatively low complication rates, though NYHA class at presentation has a significant bearing on surgical mortality and thrombus size affects complication rates with thrombolysis. Thrombolysis appears particularly favoured when the thrombus area as assessed by transoesophageal echocardiography is small (<0.8 cm2), as high success rates and low complication rates have been reported, and thrombolysis does not preclude the patient from proceeding to surgery if it fails. Presentation in a high NYHA class of heart failure or cardiogenic shock is the most difficult patient to decide between surgery and thrombolysis. Surgery for these patients may remain the mainstay of treatment unless the clot burden is particularly small or the patient's co-morbidities make surgery unacceptably high-risk.
Key Words: Prosthetic valve thrombosis; Thrombolytic therapy; Evidence-based medicine
A best evidence topic was constructed according to a structured protocol. This protocol is fully described in the ICVTS [1].
You are seeing a 72-year-old with a 12-year-old mechanical mitral valve replacement, presenting ‘in-extremis’ with breathlessness, dizziness and hypotension. Her family report that she has been confused recently and might not have taken her warfarin. An echocardiogram shows severely restricted movement of the prosthetic mitral valve leaflets with the appearance of thrombus in-situ. You wonder whether first-line treatment should be emergency surgery or thrombolytic therapy.
In [patients with obstructive prosthetic valve thrombosis] is [thrombolytic therapy or surgery] the best treatment in terms of [survival]?
Medline 1950–August 2007 using the OVID interface. [Fibrinolytic Agents/OR Thrombolytic Therapy/OR thrombolysis.mp.]AND [prosthetic valve thrombosis.mp.OR prosthetic heart valve thrombosis.mp.]LIMIT to Human.
Ninety-six papers were found in Medline. Twelve papers were deemed to be relevant. Only case series of a reasonable size (  30) were included. Two of these papers were systematic reviews with recommendations. Guidelines by the American Heart Association/American College of Cardiology (AHA/ACC) were also included. Two large case series of surgical management of prosthetic valve thrombosis (PVT) were additionally included for comparison. These papers are documented in Table 1.
The AHA/ACC published recommendations in this area in 2006 [2]. All recommendations were class IIa or IIb, based on B or C level evidence. They suggest that surgery is a reasonable first-line strategy for most patients, with consideration of thrombolysis reserved for specific situations: where the patient is in a lower NYHA class with a small clot burden, or where the patient is in a higher NYHA class with a large or small clot burden and high operative risk. Recommendations have also been produced by a Working Group of the Society for Heart Valve Disease in 2005 [3]. These took a differing line in that they gave class I guidance strongly in favour of thrombolysis for almost all patients with PVT, with surgery reserved for those in whom there is a contraindication to thrombolysis, or in whom thrombolysis has failed. Further recommendations regarding types of thrombolytic therapy are also given, along with potential contraindications. A further review paper by Cáceres-Lóriga et al. [4] also recommends thrombolysis as first-line treatment for patients with PVT presenting with NYHA class III–IV symptoms or cardiogenic shock. Repeated infusions of thrombolytic agents with serial echocardiographic assessments until thrombus resolution are also advocated, with surgery to be considered in the event of failure of thrombus dissolution despite repeated infusions. They feel that patients with NYHA class I–II symptoms may be appropriately managed with either thrombolysis or surgery depending on patient and physician preference. A meta-analysis of outcomes from thrombolysis for PVT has also been performed by Lengyel [5]. This was published as a letter and, therefore, is not fully detailed or referenced. The meta-analysis incorporates 53 studies, and results are divided into the periods 1974–1995 and 1996–2003. This shows an improvement in outcomes from thrombolysis in recent years, with a success rate of 90%, embolic event rate of 4% and mortality rate of 2.5%. The author suggests consideration of thrombolysis in all patients irrespective of functional class and thrombus size unless a contraindication exists. Lengyel's comments regarding thrombus size are interesting in the context of a paper published the same year by Tong et al. [6]. This multicentre registry was designed to evaluate the role of transoesophageal echocardiography (TOE) in risk-stratifying patients undergoing thrombolysis of PVT. It demonstrated that TOE has a potentially important role by establishing lower thrombus density as a predictor of success with thrombolysis, and larger thrombus size (along with previous history of stroke) as an independent predictor of complications. A cut-off of 0.8 cm2 was derived from ROC curve analysis. The authors, therefore, recommend TOE imaging in all cases of suspected PVT and thrombolysis in patients with small (<0.8 cm2) thrombus, especially those in NYHA class III–IV, whose surgical mortality would be high. A number of reasonably-sized case series of patients treated with thrombolysis have been published in recent years [7–11]. These demonstrate that the majority of patients present in higher NYHA classes. Success rates were consistently reported in the region of 85–90%, with mortality rates of around 5–10%. In terms of complications, embolic events were reported at rates of 6–19%, haemorrhagic events were seen in 2–8% of patients, and re-thrombosis occurred in 11–28% (many of these patients were subsequently successfully re-thrombolysed). These figures are rather less favourable than those published in the meta-analysis by Lengyel, but as discussed, it is unclear which case series were included in that paper as it was not fully referenced. Comparatively, two large case series of patients undergoing surgery for acute PVT have also been published. These were published by Deviri et al. [16] in 1991 and Roudaut et al. [15] in 2003. Overall mortality rates were found to be 12.3% in the 1991 paper and 10.3% in 2003. However, break-downs by presenting NYHA class in both papers show a marked rise in mortality from patients in NYHA class I–III (4.7% in 1991; 4% in 2003) to patients in NYHA class IV (17.5% in 1991; 24% in 2003).
Surgery has been the traditional management of choice for obstructive PVT, but thrombolysis has recently been proposed as a first-line therapy. There are no randomised controlled trials comparing these two management strategies. Therefore, recommendations are based on case series reporting success, mortality and complication rates for each. Thrombolytic therapy in recent years appears to have high success rates, with relatively low complication and mortality rates. However, complication rates are higher in patients with larger size thrombus (as measured by TOE) and in those with a previous history of stroke. Surgical management again has a high rate of success overall, but the mortality rate for patients presenting in NYHA class IV heart failure is considerably higher than that for patients in the lower NYHA classes. Essentially, therefore, either strategy may reasonably be considered for a patient with obstructive PVT, but NYHA class, thrombus size and previous history of stroke should be taken into account when making this decision. Small thrombus size (<0.8 cm2), particularly in the absence of previous stroke disease, may favour thrombolysis in view of the high success rates and low complication rates demonstrated in this situation. Additionally, treatment with a thrombolytic does not preclude subsequently reverting to surgical management in the event of failure. Presentation in a high NYHA class of heart failure or cardiogenic shock is the most difficult patient to decide between surgery and thrombolysis. Surgery for these patients may remain the mainstay of treatment unless the clot burden is particularly small or the patient's co-morbidities make surgery unacceptably high-risk.
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Abstract
1. Introduction
