Mechanical Valve Thrombosis

David Messika-Zeitoun MD, PhD and Claire Cimadevilla MDBichat Hospital, Paris, France

Medical History

• 20 years-old lady living in Tahiti • 2006: Mitral valve repair + tricuspid annuloplasty in for

severe rheumatic mitral regurgitation • 2010: mechanical valve replacement for recurrence of

mitral stenosis and mitral regurgitation• Early 2012: Pregnancy. Vitamin K antagonists were

sustained throughout pregnancy including the first trimester until the 36th week than was replaced by heparin.

• Mid-october 2012: delivery complicated by a severe hemorrhage and anticoagulation was stopped for several days

• In the following days, a large prosthetic thrombosis was diagnosed during systematic transesophageal echocardiography without any hemodynamic consequences.

• No changes after 2 weeks of correct anticoagulation + aspirin and the patient was referred to our center for surgery

Clinical and Transthoracic Echocardiographic Examination at Arrival

• Perfectly tolerated 24 hours trip• Physical examination• Markedly overweight • BP 117/75• 2/6 diastolic murmur• No sign of congestive heart failure

• ECG: sinus rhythm• Transthoracic echocardiography • Normal systolic function• Increased mean transmitral gradient (14 mm hg) despite normal leaflets

motion• Systolic pulmonary artery pressure: 40 mm Hg

2D Transesophageal Echocardiography

Watch video

LARGE OBSTRUCTIVE PROSTHETIC THROMBOSIS

Normal mobility of both leaflets (arrows) but unilateral

transprosthetic flow

3D Transesophageal Echocardiography

Large thrombus masking completely the medial leaflet (surgical view from the left atrium, left appendage (not seen) on the right)

Watch video

Management and Outcome

• The patient was operated on the next day• Surgery confirmed the large prosthetic thrombosis• A new mechanical valve (St Jude mitral n°25) was implanted

(no desire of any further pregnancy)

Take Home Message 1: Management of Mechanical Valve Thrombosis

• Obstructive valve thrombosis should be suspected promptly in any patient with any type of prosthetic valve, who presents with recent dyspnea, embolic event or inadequate anticoagulation

• The analysis of the risks and benefits of fibrinolysis should be adapted to patient characteristics and local resources.

• Urgent or emergency valve replacement is recommended for obstructive thrombosis in critically ill patients without serious comorbidity

Management of Left-sided Obstructive Prosthetic Thrombosis

Take Home Message 2: Choice of valve prosthesis

• Mechanical valves offer excellent hemodynamic performance and long-term durability, but the need for anticoagulation increases fetal and maternal mortality and morbidity.

• Bioprosthetic valves also offer good hemodynamic performance and are much less thrombogenic. Their use in young women, however, is associated with a high risk of structural valve deterioration, occurring in 50% of women <30 years of age at 10 years post-implantation, and is greater in the mitral position than in the aortic and tricuspid position.

Take Home Message 3: Anticoagulation Regimen During Pregnancy in patients with Mechanical Valve

• Pregnancy is associated with an increased maternal risk and all anticoagulation regimens carry an increased risk of miscarriage and of hemorrhagic complications, including retroplacental bleeding leading to premature birth and fetal death.

• The need for anticoagulation raises specific concerns because of an increased risk of valve thrombosis, of hemorrhagic complications, and of offspring complications.

Take Home Message 3: Anticoagulation Regimen During Pregnancy in patients with Mechanical Valve

• First trimester:• Continuation of oral anticoagulants throughout pregnancy should be considered,

after patient information and consent, when the warfarin dose is 5 mg daily (or phenprocoumon ,3 mg or acenocoumarol ,2 mg daily) because the risk of embryopathy is low (<3%), while oral anticoagulants are in large series the most effective regimen to prevent valve thrombosis. [Recommendation Class IIa Level of evidence C].

• Discontinuation of OAC between weeks 6 and 12 and replacement by adjusted-dose unfractionated heparin (a PTT ≥2× control; in high risk patients applied as intravenous infusion) or low molecular weight heparin twice daily (with dose adjustment according to weight and target anti-Xa level 4–6 hours post-dose 0.8–1.2 U/mL) should be considered in patients with a warfarin dose required of >5 mg/day (or phenprocoumon >3 mg/day or acenocoumarol >2mg/day). [Recommendation Class IIa Level of evidence C].

• Discontinuation of OACs between weeks 6 and 12 and replacement by UFH or LMWH under strict dose control (as described above) may be considered on an individual basis in patients with warfarin dose required for therapeutic anticoagulation <5 mg/day (or phenprocoumon <3 mg/day or acenocoumarol <2 mg/day). [Recommendation Class IIb Level of evidence C].

• Whatever the anticoagulation regimen, a weekly control is mandatory

Take Home Message 3: Anticoagulation Regimen During Pregnancy in patients with Mechanical Valve

• Oral anticoagulants are recommended during the second and third trimesters until the 36th week. [Recommendation Class I Level of evidence C].

• Planned vaginal delivery is usually preferred, with prior switch to heparin. A planned caesarean section may be considered as an alternative, especially in patients with a high risk of valve thrombosis, in order to keep the time without oral anticoagulants as short as possible. • Oral anticoagulants should be discontinued and dose-adjusted unfractionated

heparin (a PTT ≥2× control) or adjusted-dose low molecular weight heparin (target anti-Xa level 4–6 hours post-dose 0.8-1.2 U/mL) started at the 36th week of gestation. [Recommendation Class I Level of evidence C].

• Low molecular weight heparin should be replaced by intravenous unfractionated heparin at least 36 hours before planned delivery. Unfractionated heparin should be continued until 4–6 hours before planned delivery and restarted 4–6 hours after delivery if there are no bleeding complications. [Recommendation Class I Level of evidence C].

• If delivery starts while on oral anticoagulants , caesarean delivery is indicated. [Recommendation Class I Level of evidence C].

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