Hypo-Attenuated Leaflet Thickening and Reduced Leaflet Motion in Sutureless Bioprosthetic Aortic Valves

Bioprosthetic Aortic Valve Thrombosis: Definitions, Clinical Impact, and Management: A State-of-the-Art Review

Bioprosthetic aortic valve thrombosis is frequently detected after transcatheter and surgical aortic valve replacement due to advances in cardiac computed tomography angiography technology and standardized surveillance protocols in low-surgical-risk transcatheter aortic valve replacement trials. However, evidence is limited concerning whether subclinical leaflet thrombosis leads to clinical adverse events or premature structural valve deterioration. Furthermore, there may be net harm in the form of bleeding from aggressive antithrombotic treatment in patients with subclinical leaflet thrombosis. This review will discuss the incidence, mechanisms, diagnosis, and optimal management of bioprosthetic aortic valve thrombosis after transcatheter aortic valve replacement and bioprosthetic surgical aortic valve replacement.

Comparison of apixaban versus aspirin for the prevention of latent bioprosthetic aortic valve thrombosis: study protocol for a prospective randomized trial

BACKGROUND

The optimal antithrombotic strategy early after aortic valve replacement surgery with a biological valve remains controversial due to lack of high-quality evidence. Either oral anticoagulants or acetylsalicylic acid should be considered for the first 3 months. Hypo-attenuated leaflet thickening on cardiac computed tomography has been associated with latent bioprosthetic valve thrombosis and may be prevented with anticoagulation. We hypothesize that anticoagulation with apixaban is superior to single antiplatelet therapy with acetylsalicylic acid in reducing hypo-attenuated leaflet thickening of bioprosthetic aortic valve prostheses.

METHODS

In this prospective, open-label, randomized trial, patients undergoing isolated aortic valve replacement surgery with rapid deployment bioprosthetic valves will be randomized. The treatment group will receive 5 mg of apixaban twice a day for the first 3 months and 100 mg of acetylsalicylic acid thereafter. The control group will be administered 100 mg of acetylsalicylic acid once a day, indefinitely. After the 3-month treatment period, a contrast-enhanced electrocardiogram-gated cardiac computed tomography will be performed to identify hypo-attenuated leaflet thickening of the bioprosthetic valve. The primary objective of the study is to assess the impact of apixaban on the prevention of hypo-attenuated leaflet thickening at 3 months. The secondary and exploratory endpoints will be clinical outcomes and safety profiles of the two strategies.

DISCUSSION

Antithrombotic therapy after aortic valve replacement is used to prevent valve thrombosis and systemic thromboembolism. Latent bioprosthetic valve thrombosis is a precursor of clinically significant prosthetic valve dysfunction or thromboembolic events. The hallmark feature of latent bioprosthetic valve thrombosis is hypo-attenuated leaflet thickening on cardiac computed tomography. Subclinical leaflet thrombosis occurs frequently in bioprosthetic aortic valves, more commonly in transcatheter than in surgical valves. There is no evidence on the effect of direct oral anticoagulants on the incidence of hypo-attenuated leaflet thickening after surgical aortic valve replacement with rapid deployment bioprostheses.

TRIAL REGISTRATION

ClinicalTrials.gov NCT06184113. Registered on December 28, 2023.

Early thrombus formation including hypo-attenuated leaflet thrombosis after surgical bioprosthetic aortic valve replacement

OBJECTIVE

To assess the occurrence, predictors, and outcomes of hypo-attenuated leaflet thickening (HALT) and thrombus outside the prosthetic valve following surgical aortic valve replacement.

METHODS

A total of 118 patients underwent surgical aortic valve replacement with bioprosthetic valves between July 2020 and June 2022. Sixty-two (52.5%) patients, which is a fairly high number of patients, underwent cardiac computed tomography and transthoracic echocardiography one week after surgery. Patients were divided into two groups, those with HALT (n = 14) and those without HALT (n = 48).

RESULTS

Of the 62 patients who underwent cardiac computed tomography, HALT was observed in 14 (22.5%) patients during the very early postoperative phase. Reduced leaflet motion was observed in two of the 14 patients. The low-attenuation areas were located outside the prosthetic valve in 10 cases (71.4%) in the HALT group and in 14 cases (29.2%) in the non-HALT group. More than 50% of patients (57.1%) with HALT and 79.2% without HALT were administered warfarin. Neither in-hospital deaths nor postoperative thromboembolic events were observed during hospitalization. No patient had a mean pressure gradient > 20 mmHg in either group.

CONCLUSION

HALT was observed in one-fifth of the cases after surgical aortic valve replacement during the very early postoperative phase in an institution wherein administration of continuous heparin infusion after surgery is a standard practice. HALT did not affect the early prognosis or incidence of cerebral infarction.

Perceval sutureless bioprosthesis versus Perimount sutured bioprosthesis for aortic valve replacement in patients with aortic stenosis: a retrospective, propensity-matched study

BACKGROUND

Rapid-deployment aortic valve replacement (RDAVR) is an alternative to conventional AVR (cAVR) for aortic stenosis. Benefits include a reduction in operative times, facilitation of minimal access surgery and superior haemodynamics compared to conventional valves. However, further evidence is required to inform guidelines, preferably in the form of propensity-matched studies that include mid-term follow-up data.

METHODS

This was a single-centre, retrospective, propensity-matched cohort study comparing the Perceval and conventional Perimount Magna Ease valve for short- and mid-term clinical parameters and size-matched mid-term echocardiographic parameters (n = 102 in both groups) from 2014 to 2020. Data were extracted from a nationally managed dataset.

RESULTS

There were no demographic differences between the matched groups. The Perceval group had shorter cross-clamp time (Perceval 62 [49-81] minutes; Perimount 79 [63-102] minutes, P < 0.001), shorter bypass time (Perceval 89 [74-114] minutes; Perimount 104 [84-137] minutes, P < 0.001), and more frequent minimally-invasive approaches (Perceval 28%; Perimount 5%, P < 0.001). Size-matched haemodynamics showed initially higher gradients in the Perceval group, but haemodynamics equalised at 12 + months. The Perceval group had a more favourable % change in the left ventricular posterior wall dimension at 2 + years (Perceval - 4.8 ± 18; Perimount 17 ± 2).

CONCLUSIONS

The Perceval facilitated shorter operations, which may benefit intermediate-high-risk, elderly patients with comorbidities requiring concomitant procedures. It also facilitated minimally invasive surgery. Size-matched haemodynamic performance was similar at mid-term follow-up, with the Perceval possibly better facilitating regression of left ventricular hypertrophy.

Effects of short-term oral anticoagulation following surgical bioprosthetic aortic valve replacement

BACKGROUND

Short-term oral anticoagulation (OAC) is recommended for patients after surgical bioprosthetic aortic valve replacement (bAVR); however, the potential benefits remain controversial. This study evaluated the effects of short-term OAC following bAVR.

METHODS

From 2010 to 2017, total 450 patients who underwent bAVR were enrolled. The outcomes of patients who did (OAC group) and who did not receive OAC (without-OAC group) after bAVR were compared. Propensity-score matching (PSM) was used to adjust for potential confounders, and a 1:1 matched cohort was formed. The main outcomes were all-cause mortality and bioprosthetic valve dysfunction (BVD).

RESULTS

A total of 175 (39%) patients received OAC after bAVR. The median follow-up period was 2.9 years, the median duration of OAC use was 4 months; 162 pairs of patients were identified after the PSM. There was no significant difference in the prevalence of 1-year embolism/ischemic stroke between the OAC and without-OAC group in PSM cohort (0.62% vs. 1.89% for embolism, p = 0.623; 0 vs. 1.23% for ischemic stroke, p = 0.499). The prevalence of 1-year intracranial hemorrhage (ICH) between OAC and without-OAC group was also comparable (0.62% vs. 0.62%, p = 1). The OAC group had a lower all-cause mortality (adjusted hazard ratio (aHR):0.488, 95% confidence interval (CI): 0.259-0.919). There was also a trend for reduced BVD in the OAC group (aHR: 0.661, 95% CI: 0.339-1.290).

CONCLUSION

Our study demonstrated that short-term OAC use after bAVR was associated with lower all-cause mortality. The prevalence of 1-year embolism/ischemic stroke/ICH were comparable despite of OAC use.

Mitral Valve-in-Ring Leaflet Thrombosis: A Multimodality Imaging Primer

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Echocardiography and CT help to detect mitral THVT.

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Hypoattenuated leaflet thickening on CT indicates mitral thrombosis.

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Duration of anticoagulation to prevent mitral transcatheter valve thrombosis is unclear.

Hypo-attenuated leaflet thickening after Perceval sutureless bioprosthesis implantation

Modern multi-slice computed tomography (CT) has increased the detection of hypo-attenuated leaflet thickening (HALT). Furthermore, HALT's impact on transcatheter or surgical biological aortic valve (AV) prostheses has attracted attention. However, few reports on HALT in sutureless bioprostheses exist. Herein, we report a case of early structural valve deterioration due to HALT after AV replacement (AVR) with a Perceval bioprosthesis, which improved after anticoagulation therapy. A 79-year-old man admitted to our hospital with paroxysmal atrial fibrillation (PAF) during hemodialysis was also diagnosed with AV stenosis and, coronary artery disease, and PAF. He underwent AVR, coronary artery bypass grafting, and left atrial appendage resection. Although the postoperative course was uneventful with dual antiplatelet therapy, postoperative enhanced CT revealed HALT with reduced leaflet motion, and echocardiography showed an increased transvalvular pressure gradient. After using warfarin with target prothrombin time-international normalized ratio of 2-2.5 and/or heparin with target activated partial thromboplastin time of 45-60 s, the HALT disappeared with an improved transvalvular pressure gradient without any thromboembolic events.

Bioprosthetic Aortic Valve Thrombosis and Literature Review

An 83-year-old gentleman with a history of 23-mm Hancock-II-bioprosthetic aortic valve (BAV) replacement ten-years prior presented with symptoms of dyspnea and lower extremity edema. During the preceding seven-years, he had been noted to have asymptomatic increased mean transvalvular gradients (MG; 36–50 mmHg) felt to be due to either early bioprosthetic degeneration, pannus formation, or patient–prosthesis mismatch. An echocardiogram at the time of symptom development demonstrated significant flow acceleration through the aortic valve, mild regurgitation, and severely increased MG (48 mmHg) with prolonged acceleration time (AT, 140 msec). A trial of warfarin anticoagulation resulted in dramatic improvement after only 6 weeks with laminar flow through the AV, near-total resolution of regurgitation, and a decrease in MG to 14 mmHg and AT to 114 msec. These findings strongly suggest that BAV thrombosis was the predominant mechanism responsible for the longstanding high MG. Our case highlights that BAV thrombosis should be considered in the differential of elevated gradients regardless of the age of prosthesis, and that a trial of warfarin anticoagulation may be beneficial even if elevated gradients have been present for a prolonged period. Valvular gradients are often abnormal long before a formal diagnosis; however, these may reverse quickly with anticoagulation therapy.

Sutureless and Rapid Deployment Versus Sutured Aortic Valve Replacement: a Propensity Matched Comparison from the Sutureless and Rapid Deployment International Registry

OBJECTIVE

To compare procedural and in-hospital outcomes of patients undergoing sutureless (Perceval, Livanova PLC, London, UK) and rapid deployment (Intuity Elite, Edwards Lifesciences, Irvine, USA) aortic valve replacement (group 1) versus sutured aortic valve replacement (group 2).

METHODS

Patients receiving isolated aortic valve replacement between 2014 and 2020 were analysed using data from the Sutureless and Rapid Deployment International Registry. Patients in group 1 and group 2 were propensity-score matched in a 1:1 ratio.

RESULTS

A total of 7708 patients were included in the study. After matching, 2 groups of 2643 each were created. Patients in group 1 were more likely to undergo minimally invasive approaches and were associated with shorter operative times when compared with group 2. Overall in-hospital mortality was similar between groups. While an increased risk of stroke was observed in group 1 in the first study period (2014-2016) (relative risk 3.76, p < 0.001), no difference was found in more recent year period (relative risk 1.66, p = 0.08)(p for heterogeneity 0.003). Group 1 was associated with reduced rates of postoperative low cardiac output syndrome, atrial fibrillation and mild aortic regurgitation. New pacemaker implant was three-fold higher in group 1.

CONCLUSIONS

Our findings showed significant differences in procedural and clinical outcomes between the study groups. These results suggest that sutureless and rapid deployment aortic valve replacement should be considered as part of a comprehensive valve program. The knowledge of the respective post-aortic valve replacement benefits for different valve technologies may result in patient-tailored valve selection with improved clinical outcomes.

Transcatheter Aortic Valve Implantation: The Evolving Role of the Radiologist in 2021

BACKGROUND

 Transcatheter aortic valve implantation (TAVI) has gained worldwide acceptance and implementation as an alternative therapeutic option in patients with severe aortic valve stenosis unable to safely undergo surgical aortic valve replacement. This transformative technique places the radiologist in a key position in the pre-procedural assessment of potential candidates for this technique, delivering key anatomical information necessary for patient eligibility and procedural safety. Recent trials also provide encouraging results to potentially extend the indication to patients with safer risk profiles.

METHOD

 The review is based on a PubMed literature search using the search terms "transcatheter heart valve", "TAVI", "TAVR", "CT", "imaging", "MR" over a period from 2010-2020, combined with personal comments based on the author's experience.

RESULTS AND CONCLUSION

 CT plays a prominent role in the pre-procedural workup, delivering as a true 3D imaging modality optimal visualization of the complex anatomy of the aortic root with simultaneous evaluation of the patency of the different access routes. As such, the contribution of CT is key for the determination of patient eligibility and procedural safety. This input is supplementary to the contributions of other imaging modalities and forms an important element in the discussions of the Heart Valve Team. Knowledge of the procedure and its characteristics is necessary in order to provide a comprehensive and complete report. While the role of CT in the pre-procedural evaluation is well established, the contribution of CT and MR and the clinical significance of their findings in the routine follow-up after the intervention are less clear and currently the subject of intense investigation. Important issues remain, including the occurrence and significance of subclinical leaflet thrombosis, prosthetic heart valve endocarditis, and long-term structural valve degeneration.

KEY POINTS

  · CT plays a crucial role in evaluating transcatheter heart valve candidates. · Evaluation must include the dimensions of the aortic root and access paths. · The exact post-procedural role of CT and MRI has not yet been determined..

CITATION FORMAT

· Salgado R, El Addouli H, Budde RP. Transcatheter Aortic Valve Implantation: The Evolving Role of the Radiologist in 2021. Fortschr Röntgenstr 2021; 193: 1411 - 1425.

Transcatheter Aortic Valve Implantation and Subclinical and Clinical Leaflet Thrombosis: Multimodality Imaging for Diagnosis and Risk Stratification

In recent years, the phenomenon of subclinical leaflet thrombosis (SLT) in patients who have undergone transcatheter aortic valve implantation has become increasingly relevant. Hypo-attenuating leaflet thickening and hypo-attenuation affecting motion diagnosed by CT are the hallmarks of SLT, and their incidence varies depending on the intensity of screening. Whether these phenomena are a surrogate for leaflet thrombosis reducing valve durability and increasing the risk of stroke is still a matter of debate. Uncertainty remains over the optimal antithrombotic therapy after TAVI and the best treatment strategy is still not confirmed. Ongoing and future trials will provide more evidence about the best strategy for the prevention and treatment of SLT.

Hypo-attenuated leaflet thickening and reduced leaflet motion after the implantation of the Perceval S sutureless bioprosthesis

Hypo-attenuated leaflet thickening (HALT) is gaining attention as a relatively common issue after surgical or transcatheter aortic valve replacement (AVR). However, only a few reports have described HALT in sutureless bioprosthesis, which has emerged as a promising tool with excellent hemodynamics and enhanced implantability. We herein report a 75-year-old woman who underwent quintuple coronary artery bypass grafting and sutureless AVR with a Perceval S bioprosthesis (LivaNova PLC, London, UK). Despite an uneventful perioperative course, her recovery was slow with persistent pleural effusion. Echocardiography revealed an increased transvalvular pressure gradient, and HALT was confirmed by computed tomography. The patient received aggressive anticoagulation therapy with resolution of the HALT and made an uneventful recovery. Current guidelines provide no specific recommendations for peri-procedural antithrombotic therapy for sutureless AVR. However, HALT is not rare after sutureless AVR and can lead to significant clinical consequences. In this case, aggressive anticoagulation therapy with systemic heparinization was effective as HALT treatment following early post-sutureless AVR. Further investigation is required to determine the optimal antithrombotic strategy for sutureless AVR.

Leaflet thickening and stent geometry in sutureless bioprosthetic aortic valves

Underexpansion of transcatheter heart valves and the surgically implanted Perceval sutureless aortic valve bioprosthesis has been suggested as an underlying mechanism for hypo-attenuated leaflet thickening (HALT). This was a single-center prospective observational study that included 47 patients who underwent surgical aortic valve replacement with the Perceval sutureless bioprosthesis (LivaNova, London, United Kingdom) from 2012 to 2016 and were studied by four-dimensional cardiac computed tomography (CT). The association between overall and regional expansion and the prevalence of HALT was analyzed. In total 46 patients were included in the analysis. HALT was found in 39.1% of patients and the mean overall prosthesis expansion was 75.5 ± 5.2% (range 64.6–84.8%). Overall expansion did not differ between patients with HALT compared with patients without HALT (mean overall expansion 74.0 ± 5.2% vs. 76.5 ± 5.0%, P = 0.11). The prevalence of HALT was lower in patients with overall expansion > 80% compared to patients with expansion < 80% expansion though not significantly (20% vs. 44.4%, P = 0.16). None or trivial regional underexpansion was found in 94.7% of coronary cusps. There was no significant association between regional underexpansion and the prevalence of HALT (mean coronary cusp angle 120 ± 8° vs. 119 ± 10°, P = 0.53). The prevalence of HALT and overall underexpansion was high in the Perceval sutureless bioprosthetic valve. Overall underexpansion was not associated with HALT. Whether severe overall underexpansion increases the risk for HALT requires further study. Regional underexpansion was uncommon in the Perceval sutureless bioprosthetic valve and not associated with HALT.

Clinical trial registration Unique identifier: NCT03753126 (http://www.clinicaltrials.gov).

Bioprosthetic Heart Valve Degeneration and Dysfunction: Focus on Mechanisms and Multidisciplinary Imaging Considerations

Bioprosthetic heart valves (BPHVs) have fundamentally changed the treatment of valvular heart disease. Despite the continuous progress of BPHVs, from early valve designs for use in surgical replacement to the rapidly evolving use of transcatheter replacement techniques and designs, valve dysfunction and degeneration remain fundamental issues. Current guidelines and proposed standard definitions of BPHV dysfunction and degeneration outline the importance of imaging. Imaging plays a key role in understanding valve degeneration, including clinical imaging to identify transvalvular gradients, leaflet thickening, thrombosis, calcification, and restricted or reduced leaflet motion. Similarly, translational imaging approaches-including micro-CT, high-speed video, computational modeling, and high-resolution microscopy-and histologic analysis are crucial to understanding mechanisms of valve degeneration and factors that may contribute to valve dysfunction. This article provides an overview of valve dysfunction and degeneration and the role of imaging. © RSNA, 2019.

Rapid Deployment Versus Conventional Bioprosthetic Valve Replacement for Aortic Stenosis

BACKGROUND

Surgical aortic valve replacement using conventional biological valves (CBVs) is the standard of care for treatment of old patients with aortic valve disease. Recently, rapid deployment valves (RDVs) have been introduced.

OBJECTIVES

The purpose of this study was to report the nationwide German experience concerning RDVs for treatment of aortic valve stenosis and provide a head-to-head comparison with CBVs.

METHODS

A total of 22,062 patients who underwent isolated surgical aortic valve replacement using CBV or RDV between 2011 and 2015 were enrolled into the German Aortic Valve Registry. Baseline, procedural, and in-hospital outcome parameters were analyzed for CBVs and RDVs using 1:1 propensity score matching. Furthermore, 3 RDVs were compared with each other.

RESULTS

A total of 20,937 patients received a CBV, whereas 1,125 patients were treated with an RDV. Patients treated with an RDV presented with significantly reduced procedure (160 min [25th to 75th percentile: 135 to 195 min] vs. 150 min [25th to 75th percentile: 127 to 179 min]; p < 0.001), cardiopulmonary bypass (83 min [25th to 75th percentile: 68 to 104 min] vs. 70 min [25th to 75th percentile: 56 to 87 min]; p < 0.001), and aortic cross clamp times (60 min [25th to 75th percentile: 48 to 75 min] vs. 44 min [25th to 75th percentile: 35 to 57 min]; p < 0.001), but showed significantly elevated rates of pacemaker implantation (3.7% vs. 8.8%; p < 0.001) and disabling stroke (0.9% vs. 2.2%; p < 0.001), whereas in-hospital mortality was similar (1.7% vs. 2.2%; p = 0.22). These findings persisted after 1:1 propensity score matching. Comparison of the 3 RDVs revealed statistically nonsignificant different pacemaker rates and significantly different post-operative transvalvular gradients.

CONCLUSIONS

In this large, all-comers database, the incidence of pacemaker implantation and disabling stroke was higher with RDVs, whereas no beneficial effect on in-hospital mortality was seen. The 3 RDVs presented different complication profiles with regard to pacemaker implantation and transvalvular gradients. (German Aortic Valve Registry [GARY]; NCT01165827).

Clinical Valve Thrombosis and Subclinical Leaflet Thrombosis Following Transcatheter Aortic Valve Replacement: Is There a Need for a Patient-Tailored Antithrombotic Therapy?

Transcatheter aortic valve replacement (TAVR) has become an established therapeutic option for patients with symptomatic, severe aortic valve stenosis at increased surgical risk. Antithrombotic therapy after TAVR aims to prevent transcatheter heart valve (THV) thrombosis, in which two different entities have to be recognized: clinical valve thrombosis and subclinical leaflet thrombosis. In clinical valve thrombosis, obstructive thrombus formation leads to an increased transvalvular gradient, often provoking heart failure symptoms. Subclinical leaflet thrombosis is most often an incidental finding, characterized by a thin layer of thrombus covering the aortic side of one or more leaflets; it is also referred to as Hypo-Attenuating Leaflet Thickening (HALT) as described on multi-detector computed tomography (MDCT) imaging. This phenomenon may also affect leaflet motion and is then classified as Hypo-Attenuation affecting Motion (HAM). Even in case of HAM, the transvalvular pressure gradient remains within normal range and does not provoke heart failure symptoms. Whereas, clinical valve thrombosis requires treatment, the clinical impact and need for intervention in subclinical leaflet thrombosis is still uncertain. Oral anticoagulant therapy protects against and resolves both clinical valve thrombosis and subclinical leaflet thrombosis; however, large-scale randomized clinical trials studying different antithrombotic strategies after TAVR are still under way. This review article summarizes the currently available data within the field of transcatheter aortic valve/leaflet thrombosis and discusses the need for a patient tailored antithrombotic approach.

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.