Early acute thrombosis of bioprosthetic mitral valve presenting with cardiogenic shock

Mitral valve bio-prosthesis and annuloplasty thrombosis during extracorporeal membrane oxygenation: case series

Background

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is a well-recognized form of haemodynamic support for patients with refractory cardiogenic shock, who are unable to be weaned off cardiopulmonary bypass. Thrombosis or bleeding from cannula sites or surgical wounds are the leading cause of morbidity and mortality in these patients, and presents a delicate balance of anticoagulation during management of patients undergoing circulatory support.

Case summary

In this case series, we discuss three cases of patients undergoing mitral valve replacements or repair with thrombosis of their new bio-prosthesis in the immediate post-operative setting. All three patients were supported with VA-ECMO post-operatively, and thrombosis occurred despite anticoagulation.

Discussion

During extracorporeal membrane oxygenation, the reduced flow throughout the heart increases the risk of intra-cardiac thrombosis. This is of particular importance in the context of mitral valve replacements and repairs, where the bio-prosthesis is an additional risk factor for thrombosis. Our cases demonstrate the morbidity and mortality of such complications, with the likely aetiology being low transvalvular flow in a newly inserted valve combined with the pro-thrombotic state created by the VA-ECMO circuit.

Bioprosthetic Valve Thrombosis

Degenerative valve disease is on the rise with greater than 100,000 valve operations performed in the US alone per year. The majority of those procedures employ tissue bioprostheses to avoid the attendant risk of anticoagulation, especially in the elderly. Though traditionally this approach has been considered a superior option to avoid anticoagulation, more recent analyses have demonstrated a significant incidence of previously unrecognized thrombosis associated with bioprosthetic valves, especially with the more recent advent of the transcatheter aortic valve replacement implantations. Bioprosthetic valve thrombosis is a major cause of either acute or indolent bioprosthetic valve degeneration, and often has an elusive presentation causing delayed recognition and treatment. The literature has extensively addressed the risks and benefits of anticoagulation following bioprosthetic valve replacement to prevent bioprosthetic valve thrombosis (BPVT), without conclusive evidence-based recommendations. The duration of anticoagulation following an episode of BPVT is unclear, and lifelong anticoagulation has been suggested. The increasing use of transcatheter aortic valve replacement as an alternative to surgical aortic valve replacement in various risk groups has introduced new challenges with regards to valve thrombosis, which have been poorly studied with regards to optimal treatment and prevention. The increasing use of valve-in-valve procedures is expected to bring on further uncharted challenges.

Midterm Clinical Outcomes of the St Jude Medical Epic Porcine Bioprosthesis in the Mitral Position

BACKGROUND

The aim of this single-center study was to report the midterm clinical outcomes and hemodynamic performance of the St Jude Medical Epic porcine bioprosthesis, a tricomposite glutaraldehyde-preserved porcine bioprosthesis, in mitral position. Methods and Results: Between January 2011 and March 2017, 117 patients (62 men, 55 women; mean age, 66.7±12.8 years) who underwent mitral valve replacement (MVR) with the Epic valve were retrospectively analyzed for early and mid-term morbidity and mortality. The mean follow-up period was 2.6±1.7 years. Three operative deaths occurred, and the operative mortality rate was 2.6%. Sixteen patients died during the follow-up period. On Kaplan-Meier analysis, freedom from all-cause death and major adverse cardiovascular and cerebrovascular events at 5-year follow-up were 80.9% and 54.8%, respectively. There were 6 reoperations: 2 for structural valve deterioration (SVD), 2 for prosthetic valve endocarditis, and 2 for thrombosis. Freedom from valve-related reoperation and SVD at 5 years were 89.0% and 93.1%, respectively. On multivariate analysis, age ≥71 years (HR, 6.78; 95% CI: 2.12-25.2, P<0.01), and NYHA functional class ≥III (HR, 3.20; 95% CI: 1.03-10.4, P=0.04) were independent predictors for all-cause death. Mean mitral pressure gradient at 1 year and 2 years were 5.1±1.9 mmHg and 4.5±1.4 mmHg, respectively.

CONCLUSIONS

Mid-term clinical results and durability of the Epic valve in the mitral position are satisfactory.

Unexpected bioprosthetic mitral valve thrombus during left ventricular assist device implantation

Acute bioprosthetic valve thrombosis can occur after surgery and sometimes cause hemodynamic instability and cardiogenic shock. Risk factors for bioprosthetic valve thrombosis are hypercoagulability, atrial fibrillation, atrial dilatation, low cardiac function, and lack of anticoagulation therapy. The authors present a case of severe mitral stenosis due to bioprosthetic valve thrombus. The patient was diagnosed with dilated-phase hypertrophic cardiomyopathy and underwent mitral valve replacement. He required venoarterial extracorporeal membrane oxygenation (VA-ECMO) due to extremely low cardiac output and was scheduled for left ventricular assist device (LVAD) implantation. Transesophageal echocardiographic examination before LVAD implantation revealed severe mitral stenosis due to bioprosthetic mitral valve thrombus, which was not detected by transthoracic echocardiography in the intensive care unit and contributed to the low cardiac function. The thrombus was removed through an unscheduled left atriotomy before LVAD implantation. The possibility of bioprosthetic valve thrombosis must be considered when the patient is dependent on VA-ECMO support. Early transesophageal echocardiographic examination of the bioprosthetic valve may be helpful and contribute to surgical decision-making.