Rationale and design of POPular-TAVI: antiPlatelet therapy fOr Patients undergoing Transcatheter Aortic Valve Implantation

Aspirin Versus Warfarin after Transcatheter Aortic Valve Replacement in Low-Risk Patients: 2-Year Follow-Up

Subclinical leaflet thrombosis occurs with transcatheter heart valves (THVs) and could be associated with structural valve deterioration. The current guidelines recommend the use of antiplatelet agents after transcatheter aortic valve replacement (TAVR) but not the routine use of oral anticoagulation. Our study examines the effects of short-term warfarin therapy on THV hemodynamics at 24 months after TAVR in low-risk patients. Low-risk patients who underwent TAVR were randomly allocated 1:1 to receive low-dose aspirin (n = 50) or low-dose aspirin plus warfarin (n = 44). After 30 days of treatment, ongoing medication regimens, including anticoagulation, were at the physicians' discretion. Follow-up after a period of 24 months was available for clinical and echocardiographic outcomes. At the 24-month mark, follow-up echocardiography of the randomly allocated patients revealed just 1 additional case of new structural valve deterioration in the aspirin group (compared with the occurrence within 30 days), based on the Valve Academic Research Consortium 3 definitions. There were also no differences in mean pressure gradients (11.5 ± 0.5 mm Hg vs 11.05 ± 4.0 mm Hg, p = 0.6) or peak velocity (2.2 ± 0.5 m/s vs 2.1 ± 0.4 m/s, p = 0.7) between the groups. A composite end point (mortality, stroke, and myocardial infarction) did not show any difference between the groups at long-term follow-up (p = 0.07). In conclusion, in low-risk patients who underwent TAVR, short-term anticoagulation with warfarin did not impact clinical outcomes or THV hemodynamics by echocardiography at 24 months.

Sex Differences in Outcomes After Transcatheter Aortic Valve Replacement: A POPular TAVI Subanalysis

BACKGROUND

Stroke and bleeding are complications after transcatheter aortic valve replacement (TAVR). A higher incidence of bleeding and stroke has been reported in women, but the role of antithrombotic management pre- and post-TAVR has not been studied.

OBJECTIVES

The study sought to compare bleeding and ischemic complications after TAVR between women and men stratified by antiplatelet and oral anticoagulant (OAC) regimen.

METHODS

The POPular TAVI (Antiplatelet Therapy for Patients Undergoing Transcatheter Aortic Valve Implantation) trial was a randomized clinical trial to test the hypothesis that monotherapy with aspirin or OAC after TAVR is safer than the addition of clopidogrel. The primary endpoints of interest of this post hoc subanalysis were: 1) all bleeding; and 2) a composite of ischemic events consisting of stroke and myocardial infarction. Secondary endpoints were: 1) nonprocedural bleeding; 2) major or life-threatening bleeding; 3) minor bleeding; 4) stroke; 5) myocardial infarction; and 6) all-cause death.

RESULTS

A total of 978 patients (466 [47.6%] women) were included in this study. All bleeding and the composite of myocardial infarction and stroke rates were similar between sexes (all bleeding: 106 [22.8%] women vs 121 [23.6%] men; P = 0.815; ischemic events: 26 [5.6%] vs 36 [7.0%]; P = 0.429). However, major or life-threatening bleeding occurred more often in women (58 [12.5%]) vs men (38 [7.4%]) (P = 0.011), most of which were access site bleedings. The use of aspirin pre- and post-TAVR increased major or life-threatening bleeding in women but not in men.

CONCLUSIONS

After TAVR, overall bleeding and ischemic outcomes were similar between women and men. However, women had more major or life-threatening bleedings, especially those receiving aspirin pre- and post-TAVR.

Evolving concepts in the management of antithrombotic therapy in patients undergoing transcatheter aortic valve implantation

Thromboembolic and bleeding complications negatively impact recovery and survival after transcatheter aortic valve implantation (TAVI). Particularly, there is a considerable risk of ischaemic stroke and vascular access related bleeding, as well as spontaneous gastro-intestinal bleeding. Therefore, benefit and harm of antithrombotic therapy should be carefully balanced. This review summarizes current evidence on peri- and post-procedural antithrombotic treatment. Indeed, in recent years, the management of antithrombotic therapy after TAVI has evolved from intensive, expert opinion-based strategies, towards a deescalated, evidence-based approach. Besides per procedural administration of unfractionated heparin, this encompasses single antiplatelet therapy in patients without a concomitant indication for oral anticoagulation (OAC); and OAC monotherapy in patients with such indication, mainly being atrial fibrillation. Combination therapy should generally be avoided to reduce bleeding risk, except after recent coronary stenting where a period of dual antiplatelet therapy (aspirin plus P2Y12-inhibitor) or P2Y12-inhibitor plus OAC (in patients with an independent indication for OAC) is recommended to prevent stent thrombosis. This new paradigm in which reduced antithrombotic intensity leads to improved patient safety, without a loss of efficacy, may be particularly suitable for elderly and fragile patients. Whether this holds in upcoming populations of younger and lower-risk patients and in specific populations as patients with subclinical valve thrombosis, is yet to be proven. Finally, whether less intensive or alternative approaches should be also applied for the periprocedural management of the antithrombotic therapy, has to be determined by ongoing and future studies.

Transcatheter aortic valve implantation induces transient drop in platelet reactivity

ABSTRACT

Although recent studies described platelet reactivity (PR) changes in days following transcatheter aortic valve implantation (TAVI), precise time course and duration of these changes have not been fully investigated. The aim of this study was to investigate PR pattern during and after TAVI in multiple time points. Study included 40 consecutive patients undergoing TAVI. All patients underwent the procedure on dual antiplatelet therapy. PR was measured in seven time points: before induction of anaesthesia (T1), after heparin administration (T2), 10 minutes after initial valve implantation (T3), at the end of procedure (T4), and on 3rd, 6th and 30th postoperative day (T 5-7). PR was measured using impedance aggregometer using three different platelet aggregation agonists (arachidonic acid in ASPItest, adenosine diphosphate in ADPtest and thrombin receptor activating peptide 6 in TRAPtest). All patients underwent successful TAVI procedure. Mean PR on T1 was 22.9±23.0 U for ASPItest, 40.5±23.7 U for ADPtest and 91.7±32.5 U for TRAPtest. There was no significant difference in PR on T2. On T3, significant reduction of PR in all three tests was observed (ASPI 10.4±11.6 U (p=0.001), ADP 24.2±14.1 U (p<0.001) and TRAP 69.3±26.6 U (p<0.001)). PR nadir for all tests was reached on T5, with subsequent PR incline. PR values in all tests returned to baseline levels on T7. Our results show that successful TAVI procedure induces transient decrease in PR regardless of the platelet activation pathway.

Randomized Trial of Aspirin Versus Warfarin After Transcatheter Aortic Valve Replacement in Low-Risk Patients

BACKGROUND

The optimal antithrombotic regimen after transcatheter aortic valve replacement remains unclear.

METHODS

In this randomized open-label study, low-risk patients undergoing transfemoral transcatheter aortic valve replacement at 7 centers in the United States were randomized 1:1 to low-dose aspirin or warfarin plus low-dose aspirin for 30 days. Patients who could not be randomized were enrolled in a separate registry. Computed tomography or transesophageal echocardiography was performed at 30 days. The primary effectiveness end point was a composite of the following at 30 days: hypoattenuated leaflet thickening, at least moderately reduced leaflet motion, hemodynamic dysfunction (mean aortic valve gradient ≥20 mm Hg, effective orifice area ≤1.0 cm², dimensionless valve index <0.35, or moderate or severe aortic regurgitation), stroke, or transient ischemic attack.

RESULTS

Between July 2018 and October 2019, 94 patients were randomly assigned, 50 to aspirin and 44 to warfarin plus aspirin, and 30 were enrolled into the registry. In the intention-to-treat analysis of the randomized cohort, the composite primary effectiveness end point was met in 26.5% for aspirin versus 7.0% for warfarin plus aspirin (P=0.014; odds ratio, 4.8 [95% CI, 1.3-18.3]). The rate of hypoattenuated leaflet thickening was 16.3% for aspirin versus 4.7% for warfarin plus aspirin (P=0.07; odds ratio, 4.0 [95% CI, 0.8-20.0]). There was no excess bleeding at 30 days with anticoagulation. In the as-treated analysis of pooled randomized and registry cohorts, the rate of hypoattenuated leaflet thickening was 16.7% for aspirin versus 3.1% for warfarin plus aspirin (P=0.011; odds ratio, 6.3 [95% CI, 1.3-30.6]).

CONCLUSIONS

In low-risk transcatheter aortic valve replacement patients, anticoagulation with warfarin may prevent transcatheter heart valve dysfunction in the short term without excess bleeding. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT03557242.

Antithrombotic selection in patients undergoing transcatheter aortic valve replacement

PURPOSE

Clinical controversy regarding the most appropriate antithrombotic regimen after transcatheter aortic valve replacement remains. Current evidence, guidelines, and recommendations are discussed.

SUMMARY

Antithrombotic selection following transcatheter aortic valve replacement depends on a variety of patient-specific factors. For patients without a preexisting indication for anticoagulation, initial trials employed dual antiplatelet therapy as the postprocedural therapy of choice. Newer studies in this patient population, however, suggest single antiplatelet therapy reduces bleeding events without sacrificing ischemic protection. In patients with a preexisting indication for anticoagulation, warfarin plus single antiplatelet therapy, as opposed to triple antithrombotic therapy, offered similar ischemic protection while reducing clinically significant bleeding. Warfarin monotherapy was associated with a further reduction in bleeding events. One trial demonstrated the safety and efficacy of using apixaban in patients with concomitant atrial fibrillation; however, routine use of rivaroxaban increased adverse cardiac and bleeding events, leaving the utility of direct-acting oral anticoagulants in question.

CONCLUSION

Available evidence and current guidelines point to a lack of consensus regarding antithrombotic selection after transcatheter aortic valve replacement. Patient-specific factors and comorbidities must be considered when tailoring therapy, with an emphasis on balancing thrombotic and bleeding risks.

Aspirin with or without Clopidogrel after Transcatheter Aortic-Valve Implantation

BACKGROUND

The effect of single as compared with dual antiplatelet treatment on bleeding and thromboembolic events after transcatheter aortic-valve implantation (TAVI) in patients who do not have an indication for long-term anticoagulation has not been well studied.

METHODS

In a randomized, controlled trial, we assigned a subgroup of patients who were undergoing TAVI and did not have an indication for long-term anticoagulation, in a 1:1 ratio, to receive aspirin alone or aspirin plus clopidogrel for 3 months. The two primary outcomes were all bleeding (including minor, major, and life-threatening or disabling bleeding) and non-procedure-related bleeding over a period of 12 months. Most bleeding at the TAVI puncture site was counted as non-procedure-related. The two secondary outcomes were a composite of death from cardiovascular causes, non-procedure-related bleeding, stroke, or myocardial infarction (secondary composite 1) and a composite of death from cardiovascular causes, ischemic stroke, or myocardial infarction (secondary composite 2) at 1 year, with both outcomes tested sequentially for noninferiority (noninferiority margin, 7.5 percentage points) and superiority.

RESULTS

A total of 331 patients were assigned to receive aspirin alone and 334 were assigned to receive aspirin plus clopidogrel. A bleeding event occurred in 50 patients (15.1%) receiving aspirin alone and in 89 (26.6%) receiving aspirin plus clopidogrel (risk ratio, 0.57; 95% confidence interval [CI], 0.42 to 0.77; P = 0.001). Non-procedure-related bleeding occurred in 50 patients (15.1%) and 83 patients (24.9%), respectively (risk ratio, 0.61; 95% CI, 0.44 to 0.83; P = 0.005). A secondary composite 1 event occurred in 76 patients (23.0%) receiving aspirin alone and in 104 (31.1%) receiving aspirin plus clopidogrel (difference, -8.2 percentage points; 95% CI for noninferiority, -14.9 to -1.5; P<0.001; risk ratio, 0.74; 95% CI for superiority, 0.57 to 0.95; P = 0.04). A secondary composite 2 event occurred in 32 patients (9.7%) and 33 patients (9.9%), respectively (difference, -0.2 percentage points; 95% CI for noninferiority, -4.7 to 4.3; P = 0.004; risk ratio, 0.98; 95% CI for superiority, 0.62 to 1.55; P = 0.93). A total of 44 patients (13.3%) and 32 (9.6%), respectively, received oral anticoagulation during the trial.

CONCLUSIONS

Among patients undergoing TAVI who did not have an indication for oral anticoagulation, the incidence of bleeding and the composite of bleeding or thromboembolic events at 1 year were significantly less frequent with aspirin than with aspirin plus clopidogrel administered for 3 months. (Funded by the Netherlands Organization for Health Research and Development; POPular TAVI EU Clinical Trials Register number, 2013-003125-28; ClinicalTrials.gov number, NCT02247128.).

Anticoagulation with or without Clopidogrel after Transcatheter Aortic-Valve Implantation

BACKGROUND

The roles of anticoagulation alone or with an antiplatelet agent after transcatheter aortic-valve implantation (TAVI) have not been well studied.

METHODS

We performed a randomized trial of clopidogrel in patients undergoing TAVI who were receiving oral anticoagulation for appropriate indications. Patients were assigned before TAVI in a 1:1 ratio not to receive clopidogrel or to receive clopidogrel for 3 months. The two primary outcomes were all bleeding and non-procedure-related bleeding over a period of 12 months. Procedure-related bleeding was defined as Bleeding Academic Research Consortium type 4 severe bleeding, and therefore most bleeding at the puncture site was counted as non-procedure-related. The two secondary outcomes were a composite of death from cardiovascular causes, non-procedure-related bleeding, stroke, or myocardial infarction at 12 months (secondary composite 1) and a composite of death from cardiovascular causes, ischemic stroke, or myocardial infarction (secondary composite 2), both tested for noninferiority (noninferiority margin, 7.5 percentage points) and superiority.

RESULTS

Bleeding occurred in 34 of the 157 patients (21.7%) receiving oral anticoagulation alone and in 54 of the 156 (34.6%) receiving oral anticoagulation plus clopidogrel (risk ratio, 0.63; 95% confidence interval [CI], 0.43 to 0.90; P = 0.01); most bleeding events were at the TAVI access site. Non-procedure-related bleeding occurred in 34 patients (21.7%) and in 53 (34.0%), respectively (risk ratio, 0.64; 95% CI, 0.44 to 0.92; P = 0.02). Most bleeding occurred in the first month and was minor. A secondary composite 1 event occurred in 49 patients (31.2%) receiving oral anticoagulation alone and in 71 (45.5%) receiving oral anticoagulation plus clopidogrel (difference, -14.3 percentage points; 95% CI for noninferiority, -25.0 to -3.6; risk ratio, 0.69; 95% CI for superiority, 0.51 to 0.92). A secondary composite 2 event occurred in 21 patients (13.4%) and in 27 (17.3%), respectively (difference, -3.9 percentage points; 95% CI for noninferiority, -11.9 to 4.0; risk ratio, 0.77; 95% CI for superiority, 0.46 to 1.31).

CONCLUSIONS

In patients undergoing TAVI who were receiving oral anticoagulation, the incidence of serious bleeding over a period of 1 month or 1 year was lower with oral anticoagulation alone than with oral anticoagulation plus clopidogrel. (Funded by the Netherlands Organization for Health Research and Development; POPular TAVI EU Clinical Trials Register number, 2013-003125-28; ClinicalTrials.gov number, NCT02247128.).

Anticoagulation after Transcatheter Aortic Valve Implantation: Current Status

Transcatheter aortic valve implantation (TAVI) is the standard of care for symptomatic severe aortic stenosis. Antithrombotic therapy is required after TAVI to prevent thrombotic complications but it increases the risk of bleeding events. Current clinical guidelines are mostly driven by expert opinion and therefore yield low-grade recommendations. The optimal antithrombotic regimen following TAVI has yet to be determined and several randomised controlled trials assessing this issue are ongoing. The purpose of this article is to critically explore the impact of antithrombotic drugs, especially anticoagulants, on long-term clinical outcomes following successful TAVI.

Participants' written informed consent in low-risk pragmatic clinical trials with medicines

Introduction: An important gap within modern medicine is the lack of enough comparative effectiveness research of marketed medicines. Low-risk pragmatic randomized controlled trials (pRCTs) are those conducted resembling usual clinical practice that poses no or minimal incremental risk compared with normal clinical practice.Areas covered: This review addresses one important hurdle in the conduct of low-risk pRCTs: the need to seek participants' written informed consent.Expert opinion: The CIOMS ethical guidelines consider that any research that (a) would not be feasible or practicable to carry out without the waiver or modification, (b) has important social value, and (c) poses no more than minimal risks to participants, and that is approved by the relevant research ethics committee, could be conducted without participants' consent. It is clear that these provisions are applicable to some low-risk RCTs. Recently a research on the EU-CTR registry showed that only 2% of all ongoing phase 4 RCTs could have fulfilled the CIOMS provisions following the investigators' assessment. The EU clinical trial regulation - and that of other jurisdictions - should be debated on the suitableness of the conduct with an alteration or waiver of participants' consent of those low-risk pRCTs that fulfill the three CIOMS provisions.

Between a Rock and a Hard Place: How to Use Antithrombotics in Patients Undergoing Transcatheter Aortic Valve Replacement

Transcatheter aortic valve replacement (TAVR) has become the preferred method for management of severe aortic stenosis in patients who are at high and intermediate surgical risk, and has recently gained approval from the Food and Drug Administration in the US for use in patients at low risk for surgery. Thrombocytopenia and thromboembolic events in patients undergoing TAVR is associated with increased morbidity and mortality, and yet there is insufficient evidence supporting the current guideline-mediated therapy for antithrombotics post-TAVR. In this article, the authors review current guidelines for antithrombotic therapy in patients undergoing TAVR, studies evaluating antiplatelet regimens, and studies evaluating the use of platelet function testing after TAVR. They also offer a potential link between thrombocytopenia and antiplatelet treatments in patients undergoing TAVR.

Antithrombotic Therapy After Transcatheter Aortic Valve Replacement

The performance of transcatheter aortic valve replacement has expanded considerably during the past decade. Technological advances and refinement in implantation techniques have resulted in improved procedural outcomes, whereas indications are progressively extending toward lower-risk patients. Ischemic/embolic complications and major bleeding remain important and strongly correlate to mortality. In this regard, the optimal antithrombotic regimen after successful transcatheter aortic valve replacement remains unclear, in the absence of randomized trials. For patients without an indication for oral anticoagulation, empirical treatment with dual antiplatelet therapy (aspirin plus clopidogrel) for 3 to 6 months is currently recommended. However, dual antiplatelet therapy has been preliminarily associated with increased risk of bleeding compared with single antiplatelet therapy without significant ischemic benefit. Non-vitamin K oral anticoagulants and warfarin have also entered clinical investigation, to address the issue of preexisting or new-onset of atrial fibrillation and potentially attenuate subclinical leaflet thrombosis. Clinical trials are necessary to systematically address the risks and benefits of these approaches. In this review, we present the pathophysiological mechanisms of post-transcatheter aortic valve replacement complications and provide updated insights on the rationale behind the various antithrombotic regimens being currently evaluated in large randomized trials.

Transcatheter Aortic Valve Implantation Current Indications and Future Directions

Degenerative heart valve disease is associated with significant morbidity and mortality and healthcare expenditures. Transcatheter heart valve repair and replacement has introduced a fundamental change in the therapeutic management and transcatheter aortic valve replacement (TAVR) has gained substantial popularity. Favorable results from randomized trials and large real world registries lead to TAVR being considered a standard procedure with high rates of procedural success and low rates of peri-procedural complications. This article aims to review the past evolution, summarize the available evidence, discuss current indications and limitations and venture a glimpse into the future of percutaneous interventions for aortic valve disease.

[What antithrombotic treatment should we prescribe after transvalvular aortic valve implantation?]

The performance and indications of transvalvular aortic valve implantation or TAVI has considerably expanded and is now the first therapeutic line option in the management of severe aortic stenosis. The targeted population shares both high risk of ischemic complications, particularly stroke or subclinical leaflet thrombosis of the bioprothesis, as well as hemorrhagic complications, strongly correlated to death. Based on previous experience with intracoronary stents, a dual antiplatelet therapy has been recommended by experts' consensus. This paradigm is now challenged by the observed increased risk of hemorrhagic complications without a reduction of ischemic events. Moreover, the role of non-vitamin K oral anticoagulant in patients undergoing TAVI remains to be determined. Several large ongoing randomized controlled trials will likely change our practice within the next coming year.

Adjunct Pharmacotherapy After Transcatheter Aortic Valve Replacement: Current Status and Future Directions

Transcatheter aortic valve replacement (TAVR) is a validated treatment option for severe aortic stenosis. Ischemic and thrombotic complications remain important and strongly correlate with mortality. The optimal postprocedural antithrombotic strategy for prevention of thrombotic events remains unclear. The international guidelines for medical management following TAVR are discordant, allowing for significant variance in prescribing habits. The optimal treatment strategy has yet to be delineated. Clinical trials are ongoing to assess the risks and benefits of various strategies. We discuss the pathobiology and rationale for antithrombotic therapy after TAVR, review current evidence and guidelines, and offer a concise evidence-based approach to this subject.

In-Hospital Outcomes After Transcatheter Aortic Valve Implantation in Patients With Versus Without Chronic Thrombocytopenia

Patients with chronic thrombocytopenia (cTCP) were excluded from the pivotal transcatheter aortic valve implantation (TAVI) trials. The National Inpatient Sample was queried and propensity score matching was performed to evaluate the prevalence and impact of cTCP on in-hospital clinical outcomes after TAVI. The main outcome was in-hospital mortality in patients with versus without cTCP. Among 38,855 TAVI hospitalizations, 7,105 had a diagnosis of cTCP (18.3%). In-hospital mortality was similar in both groups (OR_adjusted 0.79; 95% confidence interval [CI] 0.57 to 1.09); however, cTCP was associated with higher risk of acute kidney injury (OR_adjusted 1.29; 95% CI 1.08 to 1.54), vascular complications (OR_adjusted 1.99; 95% CI 1.22 to 3.25), perioperative blood product transfusion (OR_adjusted 1.69; 95% CI 1.42 to 2.01), cardiac tamponade (OR_adjusted 4.04; 95% CI 1.51 to 10.82), cardiogenic shock (OR_adjusted 1.52; 95% CI 1.07 to 2.15), and use of extracorporeal membrane oxygenation (OR_adjusted 2.32; 95% CI 1.1 to 4.9). In conclusion, cTCP is common in patients who underwent TAVI and is associated with worse postprocedure clinical outcomes, however, with similar in-hospital mortality.

Stroke After Surgical Versus Transfemoral Transcatheter Aortic Valve Replacement in the PARTNER Trial

BACKGROUND

Transfemoral-transcatheter aortic valve replacement (TF-TAVR) is increasingly used to treat aortic stenosis, but risk of post-procedure stroke is uncertain.

OBJECTIVES

The purpose of this study was to assess stroke risk and its association with quality of life after surgical aortic valve replacement (SAVR) versus TF-TAVR.

METHODS

The authors performed a propensity-matched study of 1,204 pairs of patients with severe aortic stenosis treated with SAVR versus TF-TAVR in the PARTNER (Placement of AoRTic TraNscathetER Valves) trials from April 2007 to October 2014. Outcomes were: 1) 30-day neurological events; 2) time-varying risk of neurological events early (≤7 days) and late (7 days to 48 months) post-procedure; and 3) association between stroke and quality of life 1 year post-procedure by the Kansas City Cardiomyopathy Questionnaire (KCCQ) overall summary score.

RESULTS

Thirty-day stroke (5.1% vs. 3.7%; p = 0.09) was similar, but 30-day major stroke (3.9% vs. 2.2%; p = 0.018) was lower after TF-TAVR than SAVR. In both groups, risk of stroke peaked in the first post-procedure day, followed by a near-constant low-level risk to 48 months. Major stroke was associated with a decline in quality of life at 1 year in both SAVR (KCCQ score median [15th, 85th percentile]: 79 [53, 94] without major stroke vs. 64 [30, 94] with major stroke; p = 0.03) and TF-TAVR (78 [49, 96] without major stroke vs. 60 [8, 99] with major stroke; p = 0.04).

CONCLUSIONS

Despite similar early-peaking (<1 day post-procedure) neurological risk profiles, SAVR is associated with a higher risk of early major stroke than TF-TAVR. Periprocedural strategies are needed to reduce stroke risk after aortic valve procedures. (Placement of AoRTic TraNscathetER Valve Trial [PARTNER]; NCT00530894).

Antithrombotic pharmacotherapy after transcatheter aortic valve implantation: an update

Introduction: Transcatheter aortic valve implantation (TAVI) is the treatment of choice for a large proportion of patients with severe aortic stenosis. Despite numerous technological and clinical advances, TAVI remains associated with thrombotic complications requiring antithrombotic pharmacotherapy, which exposes to the risk of bleeding, especially in elderly individuals. The optimal antithrombotic regimen following TAVI is uncertain and several investigations are ongoing. Areas covered: Clinical guidelines are mostly driven by observational trials and experts' opinions, thus resulting into low-grade level of evidence. The aim of the current review is to critically explore the epidemiology, pathophysiology and prognostic value of thrombotic and bleeding events after TAVI, and to review the current literature on antithrombotic strategies following the procedure. Expert opinion: Thrombotic and bleeding events remain major complications occurring in the frail population that is currently offered TAVI. Waiting for upcoming evidence from ongoing randomized clinical trials, tailoring antithrombotic therapies based on patients' characteristics, values and circumstances is a preferable approach.

A limited number of medicines pragmatic trials had potential for waived informed consent following the 2016 CIOMS ethical guidelines

OBJECTIVES

European regulations do not allow modification or waiver of informed consent for medicines randomized controlled trials (RCTs) where the three 2016 Council for International Organizations of Medical Sciences (CIOMS) provisions are met (consent would be impractical or unfeasible, yet the trial would have high social value and pose no or minimal risk to participants). We aimed to identify whether any such trials of medicines were being conducted in Europe.

STUDY DESIGN AND SETTING

This is a survey of all phase 4 "ongoing" RCTs on the EU clinical trial register between July 1, 2016 and June 30, 2018, to identify those with potentially high levels of pragmatism. Trials that were excluded were as follows: those conducted on rare diseases; conducted on healthy volunteers (except those assessing vaccines); masked (single-, double-blind) trials; single-center trials; those where one could expect to lead patients to prefer one intervention over the other; and miscellaneous reasons. The degree of pragmatism of the RCTs was self-assessed by trials' investigators by means of the PRECIS-2 tool. Investigators of those trials considered to be highly pragmatic assessed the fulfillment of the three CIOMS provisions. Seven patients assessed the social value of the RCTs. Finally, 33 members of 11 research ethics committees (RECs) assessed the social value of the trials and whether they posed no more than minimal risk to participants. Investigators, patients, and REC members assessed the fulfillment of the CIOMS provisions as "yes," "not sure" or "no."

RESULTS

Of the 638 phase 4 trials, 420 were RCTs, and 21 of these (5%) were candidates to be pragmatic. Investigators of 15 of these 21 RCTs self-assessed their trial's degree of pragmatism: 14 were highly pragmatic. Of these 14, eight fulfilled the three CIOMS provisions. Assessments by patients and RECs were inconsistent for several trials.

CONCLUSIONS

We found few low-risk participant-level pragmatic RCTs that could be suitable for modified or waived participants' informed consent. European regulators should consider amending the current regulation and encouraging the conduct of such trials.

Antithrombotic Therapy in Transcatheter Aortic Valve Replacement

Transcatheter aortic valve replacement (TAVR) has recently emerged as an effective alternative to medical treatment or surgical aortic valve replacement in all symptomatic patients with severe aortic stenosis and high or prohibitive risk and in intermediate risk when transfemoral access is feasible. Patients undergoing TAVR are often at high risk for either bleeding or cerebrovascular complications, or both, so adjuvant antithrombotic therapies are commonly used before, during and after the procedure. Today, there is no clear evidence on the best antithrombotic regimen in this context. In this review, we will try to go through the mechanisms involved in bleeding and embolic complications and we will discuss the current points of antithrombotic treatment in patients during and after TAVR, with or without oral anticoagulation (OAC) indication.

Usefulness of Clopidogrel Loading in Patients Who Underwent Transcatheter Aortic Valve Implantation (from the BRAVO-3 Randomized Trial)

P2Y₁₂-inhibitor initiation with clopidogrel using a loading dose (LD) versus no LD (NLD) provides more rapid inhibition of platelet activation and reduced risk of ischemic events after coronary stenting. Whether a similar beneficial effect is achieved in the setting of transcatheter aortic valve implantation (TAVI) is unknown. We evaluate the effects of preprocedural clopidogrel LD versus no NLD on 48-hour and 30-day clinical outcomes after TAVI. In the BRAVO-3 trial, 802 patients with severe aortic stenosis who underwent transfemoral TAVI were randomized to intraprocedural anticoagulation with bivalirudin or unfractionated heparin. Administration of clopidogrel LD was left to the discretion of the treating physician. For this analysis, patients were stratified according to receiving clopidogrel LD (n = 294, 36.6%) or NLD (n = 508, 63.4%) before TAVI. LD patients more often received a self-expandable prosthesis using larger sheaths. P2Y₁₂-inhibitor maintenance therapy pre-TAVI was similar in patients with LD versus NLD (28.2% vs 33.1%, p = 0.16). LD versus NLD was associated with similar incidences of major adverse cardiovascular events (i e., death, myocardial infarction, or stroke) (4.1% vs 4.1%, p = 0.97) and major bleeding (8.5% vs 7.7%, p = 0.68), but a higher rate of major vascular complications (11.9% vs 7.1%, p = 0.02). Multivariable adjustment showed that clopidogrel LD did not affect any of the studied clinical events, including major vascular complications (odds ratio 0.91, 95% confidence interval 0.60 to 1.39, p = 0.67). Also patients on clopidogrel maintenance therapy and thus considered in steady state were not at reduced risk of major adverse cardiovascular events compared with patients not on clopidogrel (3.7% vs 5.2%, p = 0.36). In conclusion, in patients who underwent TAVI, use of clopidogrel LD was associated with higher vascular complications and otherwise similar clinical events compared to NLD patients.

Incidence, Predictors, Management, and Clinical Significance of New-Onset Atrial Fibrillation After Transcatheter Aortic Valve Implantation

There is limited information on the incidence, management, and prognostic impact of new-onset atrial fibrillation (NOAF) following transcatheter aortic valve implantation (TAVI) for severe aortic valve stenosis. In the prospective ASAN-TAVI registry, we evaluated a total of 347 consecutive patients who underwent TAVI from March 2010 to August 2017. The primary end point was a composite of stroke or systemic embolism at 12 months. The study subjects were categorized into 3 groups; pre-existing AF (50 patients), NOAF (31 patients), and non-AF (266 patients) group. NOAF developed in 10.4% of patients without pre-existing AF after TAVI and most cases were paroxysmal type (93.6%). Pharmacologic and electrical cardioversion were tried in 13 (41.9%) and 6 (19.4%) patients and success rates were 61.5% and 33.3%, respectively. NOAF-associated case rate for primary end point was 22.6%. Transfemoral access and cardiac tamponade were independent predictors of NOAF. Patients with NOAF, as compared with those with pre-existing AF and those without AF, had an increased 1-year rate of primary end point (24.0% vs 9.9% vs 7.2%, respectively; p <0.001). By multivariable analysis, NOAF was an independent predictor of 1-year rate of primary end point (adjusted hazard ratio: 3.31; 95% CI: 1.34 to 8.20; p = 0.010). In conclusion, patients with severe aortic valve stenosis who underwent TAVI, NOAF occurred in 10% and 1 of 4 NOAF patients experienced stroke or systemic embolization. The presence of NOAF was associated with a substantially higher risk of stroke or systemic embolization.

Antithrombotic therapy in patients undergoing transcatheter aortic valve implantation

This review provides a comprehensive overview of the available data on antithrombotic therapy after transcatheter aortic valve implantation (TAVI). In the absence of large randomised clinical trials, clinical practice is leaning towards evidence reported in other populations. Due to the greater risk of major bleeding associated with oral anticoagulation using a vitamin-K antagonist (VKA), antiplatelet therapy (APT) may be considered as the first-line treatment of patients undergoing TAVI. Overall, single rather than dual APT is preferred. However, dual APT should be considered in patients with a recent acute coronary syndrome (ie, within 6 months), complex coronary stenting, large aortic arch atheromas or previous non-cardioembolic stroke. Monotherapy with VKA should be considered if concomitant atrial fibrillation or any other indication for long-term oral anticoagulation is present. APT on top of VKA seems only reasonable in patients with recent acute coronary syndrome, extensive or recent coronary stenting or large aortic arch atheromas. A direct-acting oral anticoagulant may be considered if oral anticoagulation is indicated in the absence of contraindications. Initiation of VKA is indicated in clinical valve thrombosis, for example, with high transvalvular gradient, whereas the role of VKA in the case of subclinical leaflet thrombosis is currently uncertain.

Thromboembolic and Bleeding Complications in Transcatheter Aortic Valve Implantation: Insights on Mechanisms, Prophylaxis and Therapy

Transcatheter aortic valve implantation (TAVI) has emerged as an important alternative to surgical aortic valve repair (SAVR) for patients with severe aortic stenosis. This rapidly advancing field has produced new-generation devices being delivered with small delivery sheaths, embolic protection devices and improved retrieval features. Despite efforts to reduce the rate of thrombotic complications associated with TAVI, valve thrombosis and cerebral ischaemic events post-TAVI continue to be a significant issue. However, the antithrombotic treatments utilised to prevent these dreaded complications are based on weak evidence and are associated with high rates of bleeding, which in itself is associated with adverse clinical outcomes. Recently, experimental data has shed light on the unique mechanisms, particularly the complex haemodynamic changes at sites of TAVI, that underpin the development of post-TAVI thrombosis. These new insights regarding the drivers of TAVI-associated thrombosis, coupled with the ongoing development of novel antithrombotics which do not cause bleeding, hold the potential to deliver newer, safer therapeutic paradigms to prevent post-TAVI thrombotic and bleeding complications. This review highlights the major challenge of post-TAVI thrombosis and bleeding, and the significant issues surrounding current antithrombotic approaches. Moreover, a detailed discussion regarding the mechanisms of post-TAVI thrombosis is provided, in addition to an appraisal of current antithrombotic guidelines, past and ongoing clinical trials, and how novel therapeutics offer the hope of optimizing antithrombotic strategies and ultimately improving patient outcomes.

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.

Antithrombotic management after transcatheter aortic valve implantation

Transcatheter aortic valve implantation (TAVI) is now the accepted standard of care for patients with symptomatic severe aortic stenosis at elevated risk for conventional surgical valve replacement. Currently, societal guidelines propose the use of dual antiplatelet therapy for the prevention of thromboembolic events after TAVI in patients without an indication for oral anticoagulation. This strategy is empiric and largely based on expert consensus extrapolated from the arena of percutaneous coronary intervention. In this review, we explore the rational for using antiplatelet and/or anticoagulant strategies after TAVI, review current guidelines and the evidence underpinning them, and detail the on-going randomized trials that will shape future recommendations on this important issue.

Variation in post-TAVR antiplatelet therapy utilization and associated outcomes: Insights from the STS/ACC TVT Registry

BACKGROUND

Dual antiplatelet therapy (DAPT) is recommended following transcatheter aortic valve replacement (TAVR); however, the optimal antiplatelet strategy is undefined, and little is known about practice patterns. We aimed to describe contemporary practice patterns of antiplatelet therapy and their relationship to outcomes post-TAVR.

METHODS

The population was derived from the National Cardiovascular Data Registry, Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapies Registry with Center for Medical Services linkage for 1-year outcomes from October 1, 2011 to June 30,2016. The primary outcome measured was DAPT use in patients without anticoagulation. Secondary outcomes included death, major bleeding, myocardial infarction (MI), and stroke at 1 year.

RESULTS

Overall, 16,694 patients underwent transfemoral TAVR at 444 hospitals and were discharged without anticoagulation. Among these, 13,546 (81.1%) patients were discharged on DAPT, whereas 3,148 patients (18.9%) were discharged on monotherapy. Patients discharged on DAPT versus monotherapy were similar in age, sex, and most comorbid illnesses but had higher rates of coronary artery disease (64.6% vs 52.3%; P < .01) and peripheral artery disease (25.2% vs 22.3%; P < .01). Hospital prescribing patterns varied significantly (median frequency of DAPT 85.7%, interquartile range 94.1%-74.2%). DAPT (vs monotherapy) patients had a similar mortality risk at 1 year (adjusted hazard ratio 0.92, 95% CI 0.81-1.05), significantly higher risk for major bleeding (1.48, 1.10-1.99), and similar hazard for stroke (1.04, 0.83-1.31) and MI (1.00, 0.72-1.39).

CONCLUSIONS

In the United States, most patients were discharged on DAPT following TAVR. Practice patterns varied significantly among hospitals. Patients discharged with DAPT had a similar adjusted risk of mortality, stroke, and MI compared to antiplatelet monotherapy, although risk for bleeding was significantly higher. Future investigation is needed to define the optimal antiplatelet therapy for patients undergoing TAVR.

Thrombo-embolic prevention after transcatheter aortic valve implantation

Transcatheter aortic valve implantation (TAVI) has emerged as a valuable treatment alternative to surgical aortic valve replacement among patients with symptomatic aortic stenosis at increased surgical risk. The rapid technological evolution from early to current-generation TAVI systems with low-profile delivery catheters, bioprosthetic valves with proven midterm durability, and improved positioning and retrieval features have made important contributions to the widespread clinical use of this minimal invasive therapy. Although peri-procedural and long-term thrombotic and bleeding events after TAVI remain a relevant concern, the optimal antithrombotic strategy and duration to mitigate these risks remain unclear. This review provides an overview of recent insights in this field, and highlights current and future antithrombotic trials focusing on optimizing outcomes in patients undergoing TAVI.

Oral anti-Xa anticoagulation after trans-aortic valve implantation for aortic stenosis: The randomized ATLANTIS trial

BACKGROUND

Antithrombotic treatment regimen following transcatheter aortic valve replacement (TAVR) is not evidence-based. Apixaban, a non-vitamin K direct anticoagulant (NOAC) was shown to be superior to VKA and superior to aspirin to prevent cardioembolic stroke in non-valvular atrial fibrillation. It may have the potential to reduce TAVR-related thrombotic complications including subclinical valve thrombosis along with a better safety than the standard of care.

DESIGN

ATLANTIS is a multicenter, randomized, phase IIIb, prospective, open-label, superiority study comparing standard of care (SOC Group) versus an apixaban-based strategy (Anti-Xa Group) after successful TAVR (ClinicalTrials.gov NCT 02664649). Randomization is stratified according to the need for chronic anticoagulation therapy for a reason other than the TAVR procedure. In the experimental arm, patients receive 5 mg bid of apixaban or a reduced dose of 2.5 mg bid according to the drug label or when apixaban is combined with antiplatelet therapy. In the control arm, patients receive VKA therapy if there is an indication for oral anticoagulation or antiplatelet therapy alone (single or dual) or the combination of both if needed. The primary study end point is the composite of all-cause death, TIA/stroke, myocardial infarction, symptomatic valve thrombosis, pulmonary embolism, deep venous thrombosis, systemic embolism, life-threatening, disabling or major bleeding, according to the Valve Academic Research Consortium definitions.

CONCLUSIONS

ATLANTIS tests the superiority of an apixaban-based strategy versus the recommended standard of care strategy to reduce the risk of post-TAVR thromboembolic and bleeding complications in an all comer population.

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.

Comparison of single versus dual antiplatelet therapy after TAVR: A systematic review and meta-analysis

OBJECTIVE

We aim to evaluate the efficacy of dual versus single anti-platelet therapy (SAPT) after TAVR through a systematic review and meta-analysis of published research.

BACKGROUND

Dual antiplatelet therapy (DAPT) with aspirin and clopidogrel is a commonly practiced strategy after transcatheter aortic valve replacement (TAVR). However, there is lack of sufficient evidence supporting this approach.

METHOD

We searched PubMed, EMBASE, the Cochrane Central Register of Controlled trials, and the clinical trial registry maintained at clinicaltrials.gov for randomized control trials (RCT) and observational studies comparing DAPT with SAPT post TAVR. Event rates were compared using a forest plot of relative risk with 95% confidence intervals using a random-effects model assuming inter-study heterogeneity.

RESULTS

A total of six studies (3 RCTs and 3 observational studies, n = 840) were included in the final analysis. Compared to SAPT, DAPT was associated with increased risk of significant bleeding (life threatening and major) [RR = 2.52 (95% CI 1.62-3.92, P < 0.0001)] with the number needed to harm for major or life-threatening bleeding calculated to be 10.4. There was no significant difference in the incidence of stroke [RR = 1.06 (95% CI, 0.43-2.60, P = 0.90)], spontaneous myocardial infarction [RR = 2.08 (95% CI, 0.56-7.70, P = 0.27)] and all-cause mortality [RR = 1.18 (95% CI, 0.68-2.05, P = 0.56] in the DAPT and SAPT groups.

CONCLUSION

In this small meta-analysis of DAPT versus SAPT after TAVR, DAPT did not prevent stroke, myocardial infarction or death while the risk of bleeding was higher. Results from ongoing trials are awaited to determine the best anti-thrombotic approach after TAVR.

Retinal embolic events: frequency and impact following transcatheter aortic valve implantation (TAVI) for aortic stenosis

Objectives

Transcatheter aortic valve implantation (TAVI) is an established treatment for patients with severe symptomatic aortic stenosis. It has a cerebrovascular accident rate of about 5% but the effect on retinal embolic events has not been previously reported. This study investigated the occurrence of retinal emboli following TAVI.

Methods and analysis

In this prospective observational study, 20 patients underwent full ophthalmic examination to assess retinal embolic events prior to TAVI and at 48 hours and 1 month post-TAVI.

Results

At 48 hours post-TAVI, one patient had a new cotton wool spot in the right eye. At 1 month, another two patients had new retinal emboli events in at least one eye and a fourth patient developed retinal splinter haemorrhages in the right eye.

Conclusion

Retinal embolic events and new retinal abnormalities following TAVI occurred in 15% and 20% of our cohort, respectively, without any associated retinal damage or significant visual problems. Retinal evaluation may be a useful surrogate test for cerebral embolisation in future studies assessing the utility of new valve prostheses and embolic protection devices

Usefulness of the CHA2DS2-VASc Score to Predict Outcome in Patients Who Underwent Transcatheter Aortic Valve Implantation

Risk assessment for transcatheter aortic valve implantation (TAVI) patients remains challenging, especially in elderly and high-risk candidates. Although several risk factors contribute to increased morbidity and mortality after TAVI, simple risk scores for routine use are lacking. Applying the CHA₂DS₂-VAS_C (congestive heart failure, hypertension, age ≥ 75 years, diabetes, prior stroke, vascular disease, age 65-74 years, sex [female] category) score as a novel risk stratification tool for conditions other than atrial fibrillation and stroke prevention has been previously examined; however, its usefulness in a population of patients with aortic stenosis after TAVI has not been established. Thus, we investigated 633 consecutive patients who underwent TAVI between November 2008 and May 2017, and calculated the CHA₂DS₂-VAS_C score. Patients were stratified according to their CHA₂DS₂-VAS_C score into 3 categories (0 to 3, 4 to 6, 7 to 9), and the association between CHA₂DS₂-VAS_C score and 1-year clinical outcomes (stroke, all-cause mortality, and combined outcome of stroke or mortality) was evaluated. We found that both stroke and mortality at 1 year were significantly more frequent with increasing CHA₂DS₂-VAS_C score (p = 0.012 and p = 0.025, respectively). Each single-point rise in CHA₂DS₂-VAS_C score was associated with a 38% increase in the 1-year combined outcome of mortality or stroke (p = 0.022; C index 0.615). In conclusion, CHA₂DS₂-VAS_C score can be used as a simple and effective tool to predict 1-year clinical outcomes including death and stroke in patients who underwent TAVI.

Adjuvant Antithrombotic Therapy in TAVR

PURPOSE OF REVIEW

Transcatheter aortic valve replacement (TAVR) has developed into an important alternative to surgical aortic valve replacement (SAVR) for patients with severe aortic stenosis (AS). Adjuvant antithrombotic therapies are commonly used during and after TAVR to decrease the risk of valve thrombosis and thromboembolic cerebrovascular events (CVEs) but consequently increase the risk of bleeding. This article reviews the past and current clinical data regarding adjuvant antithrombotic therapies in TAVR.

RECENT FINDINGS

Cerebrovascular and bleeding events during and after TAVR are associated with substantial morbidity and mortality. Bivalirudin, a direct thrombin inhibitor, has been shown to be safe alternative to unfractionated heparin (UFH) as procedural anticoagulation during TAVR; however, sparse evidence exists to guide use of antiplatelet and anticoagulant therapies in patients after TAVR. Multiple studies comparing different antithrombotic regimens in the post-TAVR setting are currently underway. Current guidelines recommend intra-procedural anticoagulation with UFH for during TAVR and with dual antiplatelet therapy (DAPT) after TAVR. There is a need to better understand the role of adjuvant antithrombotic therapies in TAVR. The results of ongoing studies are needed to develop evidence-based guidance for the use of adjuvant antithrombotic therapies after TAVR.

Transcatheter aortic valve implantation: where are we now?

Transcatheter aortic valve implantation (TAVI) was first used in clinical practice in 2002. Since 2002, there has been a rapid increase in TAVI activity in patients with symptomatic severe aortic stenosis. This has been supported by systematic randomized data comparing TAVI against the gold standard treatment for the last 50 years’ surgical aortic valve replacement. TAVI is now currently a recommended therapeutic intervention in the treatment of severe aortic stenosis patients who are deemed either high risk or inoperable. The indications for TAVI continue to expand. Within this review we will focus on the current guidelines for TAVI, the evidence for it, the complications of TAVI, postprocedure care, the technology available to clinicians now and finally the future perspectives for TAVI.

Antithrombotic Therapy After Transcatheter Aortic Valve Implantation

Current guidelines for patients who are undergoing transcatheter aortic valve implantation but who do not require anticoagulation recommend double antiplatelet therapy for 3-6 months after the procedure, followed by aspirin indefinitely. However, these guidelines are based on expert consensus rather than clinical trials. Several randomized trials are currently evaluating alternative antithrombotic strategies, and recommendations will likely change when their results become available.