Valve thrombosis following transcatheter aortic valve implantation: a systematic review

Increased utilization of bioprosthetic aortic valve technology:Trends, drivers, controversies and future directions

Introduction: Bioprosthetic valves (BPV) implanted surgically or by transcatheter valve implantation (TAVI) comprise an overwhelming majority of substitute aortic valves implanted worldwide.Areas Covered: Prominent drivers of this trend are: 1) BPV patients have generally better outcomes than those with a mechanical valve, and remain largely free of anticoagulation and its consequences; 2) BPV durability has improved over the years; and 3) the expanding use of TAVI and valve-in-valve (VIV) procedures permitting interventional management of structural valve degeneration (SVD). Nevertheless, key controversies exist: 1) optimal anticoagulation regimens for surgical and TAVI BPVs; 2) the incidence, mechanisms and mitigation strategies for SVD; 3) the use of VIV for treatment of SVD, and 4) valve selection recommendations for difficult cohorts, (e.g. patients 50-70 years, patients <50, childbearing age women). This communication reviews trends in and drivers of BPV utilization, current controversies, and future directions affecting BPV use.Expert Opinion: Long-term data are needed in several areas related to aortic BPV use, including anticoagulation/antiplatelet therapy, especially following TAVI. TAVI and especially VIV durability and optimal use warrant will benefit greatly from long-term data. Certain populations may benefit from such high-quality data on multi-year outcomes, particularly younger patients.

A Case of Acute Massive Bioprosthetic Mitral Valve Thrombosis Leading to Fulminant Heart Failure

Bioprosthetic valve thrombosis has been considered to be extremely unlikely, typically freeing patients from the potential complications of long-term anticoagulation. However, there have been several documented cases of bioprosthetic valve thrombosis and there are concerns that its incidence may be underreported. Experience with diagnosis and management of this condition is limited. Here, we present a case of acute massive bioprosthetic mitral thrombosis manifesting as fulminant heart failure.

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.

Implantation Depth and Rotational Orientation Effect on Valve-in-Valve Hemodynamics and Sinus Flow

BACKGROUND

This study evaluated the effect of transcatheter aortic valve implantation depth and rotation on pressure gradient (PG), leakage fractions (LF), leaflet shear stress, and sinus washout in an effort to understand factors that may dictate optimal positioning for valve-in-valve (ViV) procedures. Sinus flow stasis is often associated with prosthetic leaflet thrombosis. Although recent ViV in vitro studies highlighted potential benefits of transcatheter aortic valve supraannular implantation to minimize PGs, the relationship between transcatheter aortic valve depth and other determinates of valve function remains unknown. Among these, LFs, shear stress, and poor sinus washout have been associated with poorer valve outcomes.

METHODS

ViV hemodynamic performance was evaluated in vitro vs axial positions -9.8, -6.2, 0, and +6 mm and angular orientations 0, 30, 60, and 90 degrees in a degenerated surgical aortic valve. PGs, LFs, and sinus shear stress and washout were compared. Leaflet high-speed imaging and particle-image velocimetry were performed to elucidate hemodynamic mechanisms.

RESULTS

(1) The PG varies as a function of axial position, with supraannular deployments yielding a maximum benefit of 7.85 mm Hg less than PGs for subannular deployments irrespective of commissural alignment (p < 0.01); (2) in contrast, LF decreased in relationship to subannular deployment; and (3) at peak systole, sinus flow shear stress increased with deployment depth as did sinus washout with and without coronary flow.

CONCLUSIONS

First, supraannular axial deployment is associated with lower PGs irrespective of commissural alignment. Second, subannular deployment is associated with more favorable sinus hemodynamics and less LF. Further in vivo studies are needed to substantiate these observations and facilitate optimal prosthesis positioning during ViV procedures.

Oral Anticoagulant Therapy for Early Post-TAVI Thrombosis

While transcatheter aortic valve implantation (TAVI) is now the accepted treatment option of choice for patients presenting with severe symptomatic aortic stenosis who are deemed to be inoperable or of high surgical risk, there have been concerns regarding the risk of early valve failure and durability. One potential limitation is the occurrence of early post-TAVI thrombosis. Whilst the incidence of obstructive transcatheter heart valve (THV) thrombosis is <1 %, with technological advances in imaging, it is increasingly apparent that the overall true incidence is likely to be much higher with between 7-40 % of patients observed to have appearances strongly suggestive of asymptomatic subclinical THV thrombosis. This short review discusses the diagnosis of early THV thrombosis and the role of anticoagulation therapy for the management of these patients.

Optimising the Haemodynamics of Aortic Valve-in-valve Procedures

Bioprosthetic surgical valves are increasingly implanted during cardiac surgery, instead of mechanical valves. These tissue valves are associated with limited durability and as a result transcatheter valve-in-valve procedures are performed to treat failed bioprostheses. A relatively common adverse event of aortic valve-in-valve procedures is residual stenosis. Larger surgical valve size, supra-annular transcatheter heart valve type, as well as higher transcatheter heart valve implantation depth, have all been shown to reduce the incidence of elevated post-procedural gradients. With greater understanding of technical considerations and surgical planning, valve-in-valve procedures could be more effective and eventually may become the standard of care for our increasingly ageing and comorbid population with failed surgical bioprostheses.

A Case of Severe Late Transcatheter Heart Valve Thrombosis with Successful Response to Anticoagulation

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A case of very severe transcatheter heart valve thrombosis is described.

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The patient was treated with warfarin with success.

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The first line of treatment of transcatheter heart valve thrombosis is anticoagulation.

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A trial of 2-3 months of warfarin should be tried before considering alternatives.

Course of early subclinical leaflet thrombosis after transcatheter aortic valve implantation with or without oral anticoagulation

BACKGROUND

After transcatheter aortic valve implantation, early leaflet thickening, presumably reflecting thrombus, has recently been described on computed tomography angiography (CTA) in ~10% of the patients. We sought to investigate the impact of the antithrombotic regimen on the course of leaflet thickening.

METHODS

The study comprised 51 patients with leaflet thickening. Based on the time period, patients without an established indication for anticoagulation were put on phenprocoumon plus clopidogrel for at least 3 months or on dual antiplatelet therapy with aspirin and clopidogrel. Follow-up CTAs were evaluated for leaflet restriction, assessed by four-point-grading score, and maximal thickness.

FINDINGS

The anticoagulation and the dual antiplatelet therapy group comprised 29 and 22 patients, respectively. After a median of 86 days, we obtained follow-up CTAs in 22 patients on anticoagulation and in 16 patients on dual antiplatelet therapy. Leaflet thickening progressed in 11 on dual antiplatelet therapy, but always regressed onanticoagulation. The course of leaflet restriction and maximal thickness was significantly different between the two groups (P < 0.001): in the dual antiplatelet therapy group, maximal thickness increased by a mean of 1.37 ± 1.67 mm (P = 0.005) and leaflet restriction score by a median 1[quartiles 0;2] (P = 0.013), whereas in the anticoagulation group, maximal thickness regressed by 2.57 ± 1.52 mm (P < 0.001) and leaflet restriction score decreased by 1[-4;0] (P = 0.001). After a median of 91 days after discontinuation of anticoagulation, CTA performed in ten patients revealed a significant recurrent increase in leaflet restriction score and maximal thickness (P = 0.023, P = 0.007). In the entire cohort, changes in leaflet restriction correlated significantly with changes in transvalvular pressure gradients (r = 0.511, P < 0.001).

INTERPRETATION

The course of leaflet restriction was fundamentally different depending on the presence or absence of anticoagulation, with consistent regression under phenprocoumon, but mostly progression under antiplatelet therapy alone. Changes in leaflet restriction were associated with changes in transvalvular pressure gradients.

The role of TTE in assessment of the patient before and following TAVI for AS

Transcatheter aortic valve implantation is now accepted as a standard mode of treatment for an increasingly large population of patients with severe aortic stenosis. With the availability of this technique, echocardiographers need to be familiar with the imaging characteristics that can help to identify which patients are best suited to conventional surgery or transcatheter aortic valve implantation, and what parameters need to be measured. This review highlights the major features that should be assessed during transthoracic echocardiography before presentation of the patient to the 'Heart Team'. In addition, this review summarises the aspects to be considered on echocardiography during follow-up assessment after successful implantation of a transcatheter aortic valve.