Low-dose acetyl salicylic acid versus oral anticoagulation after bioprosthetic aortic valve replacement. Final report of the ACTION registry

Correlations between the alpha-Gal antigen, antibody response and calcification of cardiac valve bioprostheses: experimental evidence obtained using an alpha-Gal knockout mouse animal model

Introduction

Preformed antibodies against αGal in the human and the presence of αGal antigens on the tissue constituting the commercial bioprosthetic heart valves (BHVs, mainly bovine or porcine pericardium), lead to opsonization of the implanted BHV, leading to deterioration and calcification. Murine subcutaneous implantation of BHVs leaflets has been widely used for testing the efficacy of anti-calcification treatments. Unfortunately, commercial BHVs leaflets implanted into a murine model will not be able to elicit an αGal immune response because such antigen is expressed in the recipient and therefore immunologically tolerated.

Methods

This study evaluates the calcium deposition on commercial BHV using a new humanized murine αGal knockout (KO) animal model. Furtherly, the anti-calcification efficacy of a polyphenol-based treatment was deeply investigated. By using CRISPR/Cas9 approach an αGal KO mouse was created and adopted for the evaluation of the calcific propensity of original and polyphenols treated BHV by subcutaneous implantation. The calcium quantification was carried out by plasma analysis; the immune response evaluation was performed by histology and immunological assays. Anti-αGal antibodies level in KO mice increases at least double after 2 months of implantation of original commercial BHV compared to WT mice, conversely, the polyphenols-based treatment seems to effectively mask the antigen to the KO mice's immune system.

Results

Commercial leaflets explanted after 1 month from KO mice showed a four-time increased calcium deposition than what was observed on that explanted from WT. Polyphenol treatment prevents calcium deposition by over 99% in both KO and WT animals. The implantation of commercial BHV leaflets significantly stimulates the KO mouse immune system resulting in massive production of anti-Gal antibodies and the exacerbation of the αGal-related calcific effect if compared with the WT mouse.

Discussion

The polyphenol-based treatment applied in this investigation showed an unexpected ability to inhibit the recognition of BHV xenoantigens by circulating antibodies almost completely preventing calcific depositions compared to the untreated counterpart.

Risks and benefits of concurrent treatment with antiplatelet and anticoagulation therapy in post-op bioprosthetic aortic valve replacement patients

BACKGROUND AND AIM

Among patients receiving surgical bioprosthetic aortic valve replacement (bAVR), there is an elevated risk of thromboembolic events postoperatively. However, the risks and benefits of varying anticoagulation strategies remain controversial. The aim of this study is to compare the risks and benefits of aspirin monotherapy to aspirin plus warfarin ("concurrent therapy") in patients receiving bAVR.

METHODS

A retrospective cohort study was conducted using patients' data from Kaiser Permanente Northern California, including those who underwent bAVR with or without coronary artery bypass grafting between 2009 and 2018. Patients were identified as having been discharged with aspirin only or concurrent therapy. The outcomes were mortality, thromboembolic events, and clinically relevant bleeding during a 6-month follow-up. The event rates were compared using the Kaplan-Meier method. Multivariable survival analysis, incorporating propensity scores, was used to estimate adjusted hazard ratios (aHRs) for each outcome.

RESULTS

The cohort consisted of 3047 patients. Approximately 58% of patients received aspirin only and 42% received concurrent therapy. Patients who received concurrent therapy were more likely to be older, have hypertension, previous stroke, and longer hospital stays. After adjustment using multivariable analysis, concurrent therapy was associated with a higher risk of clinically relevant bleeding (aHR, 2.33; 95% confidence interval, 1.67-3.25). There was no significant difference in the risk of thromboembolic events or mortality between the two groups.

CONCLUSION

Patients who underwent bAVR and were discharged on concurrent therapy compared to aspirin only had a significantly increased risk of bleeding without a significant difference in thromboembolic events.

Anticoagulation and antiplatelet therapy in patients with prosthetic heart valves

BACKGROUND

The choice of antithrombotic therapy, anticoagulants or antiplatelets, after prosthetic heart valve replacement or repair, remains a disputed topic in the literature. Antithrombotic therapies are used after heart valve intervention to reduce the rates of thromboembolic events, therefore improving patient outcomes. Different interventions may require different therapeutic regimens to achieve the most efficacious clinical outcome for patients.

METHODS AND DISCUSSION

This review aims to summarize and critique the available literature concerning therapeutic agents used for bioprosthetic and mechanical valves as well as for valve repair, so as to assist clinicians and researchers in making decisions with regard to their patients and research endeavors.

Follow-up and management of valvular heart disease patients with prosthetic valve: a clinical practice guideline for Indian scenario

PURPOSE

Valvular heart disease (VHD) patients after prosthetic valve implantation are at risk of thromboembolic events. Follow-up care of patients with prosthetic valve has a paramount role in reducing the morbidity and mortality. Currently, in India, there is quintessential need to stream line the follow-up care of prosthetic valve patients. This mandates the development of a consensus guideline for the antithrombotic therapy in VHD patients post prosthetic valve implantation.

METHODS

A national level panel was constituted comprising 13 leading cardio care experts in India who thoroughly reviewed the up to date literature, formulated the recommendations, and developed the consensus document. Later on, extensive discussions were held on this draft and the recommendations in 8 regional meetings involving 79 additional experts from the cardio care in India, to arrive at a consensus. The final consensus document is developed relying on the available evidence and/or majority consensus from all the meetings.

RESULTS

The panel recommended vitamin K antagonist (VKA) therapy with individualized target international normalized ratio (INR) in VHD patients after prosthetic valve implantation. The panel opined that management of prosthetic valve complications should be personalized on the basis of type of complications. In addition, the panel recommends to distinguish individuals with various co-morbidities and attend them appropriately.

CONCLUSIONS

Anticoagulant therapy with VKA seems to be an effective option post prosthetic valve implantation in VHD patients. However, the role for non-VKA oral therapy in prosthetic valve patients and the safety and efficacy of novel oral anticoagulants in patients with bioprosthetic valve need to be studied extensively.

Antithrombotic Strategies After Bioprosthetic Aortic Valve Replacement: A Systematic Review

BACKGROUND

The optimal antithrombotic regimen after bioprosthetic aortic valve replacement (bAVR) is unclear. We conducted a systematic review of various anticoagulation strategies following surgical or transcatheter bAVR (TAVR).

METHODS

We searched Medline, PubMed, Embase, Evidence-Based Medicine Reviews, and gray literature through June 2017 for controlled clinical trials and cohort studies that directly compared different antithrombotic strategies in nonpregnant adults who had undergone bAVR. We assessed risk of bias and graded the strength of the evidence using established methods.

RESULTS

Of 4,554 titles reviewed, 6 clinical trials and 13 cohort studies met inclusion criteria. We found moderate-strength evidence that mortality, thromboembolic events, and bleeding rates are similar between aspirin and warfarin after surgical bAVR. Observational data suggest lower mortality and thromboembolic events with aspirin combined with warfarin compared with aspirin alone after surgical bAVR, but the effect size is small and the combination is associated with a substantial increase in bleeding risk. We found insufficient evidence for all other treatment comparisons in surgical bAVR. In TAVR patients, we found moderate-strength evidence that mortality, stroke, and major cardiac events are similar between dual antiplatelet therapy and aspirin alone, though a nonsignificantly lower rate of bleeding occurred with aspirin alone.

CONCLUSIONS

Treatment with warfarin or aspirin leads to similar outcomes after surgical bAVR. Combining aspirin with warfarin may lead to a small decrease in thromboembolism and mortality, but is accompanied by increased bleeding. For TAVR patients, aspirin is equivalent to dual antiplatelet therapy for reducing thromboembolism and mortality, with a possible decrease in bleeding.

Risk stratification of severe aortic stenosis according to new guidelines: long term outcomes

Background

Current ESC and ACC/AHA guidelines for the management of valvular heart disease assign a class Ia indication for aortic valve replacement (AVR) only to patients with symptomatic severe aortic valve stenosis and asymptomatic patients with depressed left ventricular ejection fraction (LVEF <50%) or positive exercise test. We examined the long-term outcomes for patients undergoing AVR for aortic stenosis over a 11-year period at our institution compared to current international guidelines for AVR.

Methods

Patients who had undergone isolated AVR for severe aortic valve stenosis between January 2001 and December 2012 were selected. The population was divided into subgroups based on preoperative LVEF (< or ≥50%) and on presence/absence of symptoms (NYHA =I or ≥II, respectively).

Results

We identified 607 patients with a median follow-up (FU) time of 5.75 years (IQR 3.24-8.00 years). The presence of symptoms did not have a significant impact on cardiovascular mortality (P=0.201). Patients with LVEF <50% displayed a higher long-term cardiovascular mortality rate (P=0.015). Multivariate analysis showed that preserved LVEF was a protective factor for asymptomatic patients (P=0.021), while preoperative LVEF did not affect the mortality rate in symptomatic patients (HR 0.88; 95% CI, 0.54-1.44). Correspondingly, asymptomatic patients with reduced LVEF were found to be at a higher risk of long-term mortality compared to the other groups (P=0.011). The only other independent risk factor for death was age (HR 6.46; 95% CI, 2.22-18.76).

Conclusions

According to our data, current international class I indications for symptomatic patients ensure good long-term survival, while class I indications for asymptomatic patients with reduced LVEF are associated with poor long-term survival. Our results suggest that early surgery should also be considered also for asymptomatic patients with preserved LVEF, particularly in cases of very low operative risk.

[Antiplatelet or anticoagulative strategies after surgical/interventional valve treatment]

At the end of August 2017 the European Society of Cardiology (ESC) and the European Association for Cardio-Thoracic Surgery (EACTS) published new joint guidelines for the treatment of valvular heart disease. These guidelines incorporate the scientific progress since the last version of the guidelines published in 2012. This article reviews current guideline recommendations for antiplatelet and anticoagulative therapy after surgical/interventional treatment of the aortic and mitral valves and discusses the underlying scientific evidence.

Safety and Use of Anticoagulation After Aortic Valve Replacement With Bioprostheses: A Meta-Analysis

BACKGROUND

The American College of Cardiology guidelines recommend 3 months of anticoagulation after replacement of the aortic valve with a bioprosthesis. However, there remains great variability in the current clinical practice and conflicting results from clinical studies. To assist clinical decision making, we pooled the existing evidence to assess whether anticoagulation in the setting of a new bioprosthesis was associated with improved outcomes or greater risk of bleeding.

METHODS AND RESULTS

We searched the PubMed database from the inception of these databases until April 2015 to identify original studies (observational studies or clinical trials) that assessed anticoagulation with warfarin in comparison with either aspirin or no antiplatelet or anticoagulant therapy. We included the studies if their outcomes included thromboembolism or stroke/transient ischemic attacks and bleeding events. Quality assessment was performed in accordance with the Newland Ottawa Scale, and random effects analysis was used to pool the data from the available studies. I(2) testing was done to assess the heterogeneity of the included studies. After screening through 170 articles, a total of 13 studies (cases=6431; controls=18210) were included in the final analyses. The use of warfarin was associated with a significantly increased risk of overall bleeding (odds ratio, 1.96; 95% confidence interval, 1.25-3.08; P<0.0001) or bleeding risk at 3 months (odds ratio, 1.92; 95% confidence interval, 1.10-3.34; P<0.0001) compared with aspirin or placebo. With regard to composite primary outcome variables (risk of venous thromboembolism, stroke, or transient ischemic attack) at 3 months, no significant difference was seen with warfarin (odds ratio, 1.13; 95% confidence interval, 0.82-1.56; P=0.67). Moreover, anticoagulation was also not shown to improve outcomes at time interval >3 months (odds ratio, 1.12; 95% confidence interval, 0.80-1.58; P=0.79).

CONCLUSIONS

Contrary to the current guidelines, a meta-analysis of previous studies suggests that anticoagulation in the setting of an aortic bioprosthesis significantly increases bleeding risk without a favorable effect on thromboembolic events. Larger, randomized controlled studies should be performed to further guide this clinical practice.

The TRIBECA study: (TRI)fecta (B)ioprosthesis (E)valuation versus (C)arpentier Magna-Ease in (A)ortic position

OBJECTIVE

To determine whether the Trifecta bioprosthetic aortic valve produces postoperative haemodynamic results comparable with or better than those of the Magna Ease aortic valve bioprosthesis.

METHODS

We retrospectively reviewed the medical records of patients who had undergone aortic valve replacement with Trifecta or Magna Ease prostheses at eight European institutions between January 2011 and May 2013, and analysed early postoperative haemodynamic performance by means of echocardiography.

RESULTS

A total of 791 patients underwent aortic valve replacement (469 Magna Ease, 322 Trifecta). Haemodynamic variables were evaluated on discharge and during the follow-up (minimum 6 months, maximum 12 months). The mean gradient and the indexed effective orifice area (IEOA) were as follows: 10 mmHg [interquartile range (IQR): 8-13] and 1.10 cm(2)/m(2) (IQR: 0.95-1.27) for Trifecta; 16 mmHg (IQR: 11-22) and 0.96 cm(2)/m(2) (IQR: 0.77-1.13) for Magna Ease (P < 0.001). These significant differences were maintained across all valve sizes. Similar statistically significant differences were found when patients were matched and/or stratified for preoperative characteristics: body-surface area, ejection fraction, mean gradients and valve size. Severe prosthesis-patient mismatch (IEOA: <0.65 cm(2)/m(2)) was detected in 2 patients (0.6%) with Trifecta and 40 patients (8.5%) with Magna Ease (P < 0.001).

CONCLUSIONS

The haemodynamic performance of the Trifecta bioprosthesis was superior to that of the Magna Ease valve across all conventional prosthesis sizes, with almost no incidence of severe patient-prosthesis mismatch. The long-term follow-up is needed to determine whether these significant haemodynamic differences will persist, and influence clinical outcomes.