Shear Forces Induced Platelet Clearance Is a New Mechanism of Thrombocytopenia.

BACKGROUND: Thrombocytopenia has been consistently described in patients with extracorporeal membrane oxygenation (ECMO) and associated with poor outcome. However, the prevalence and underlying mechanisms remain largely unknown, and a device-related role of ECMO in thrombocytopenia has been hypothesized. This study aims to investigate the mechanisms underlying thrombocytopenia in ECMO patients. METHODS: In a prospective cohort of 107 ECMO patients, we investigated platelet count, functions, and glycoprotein shedding. In an ex vivo mock circulatory ECMO loop, we assessed platelet responses and VWF (von Willebrand factor)-GP Ibα (glycoprotein Ibα) interactions at low- and high-flow rates, in the presence or absence of red blood cells. The clearance of human platelets subjected or not to ex vivo perfusion was studied using an in vivo transfusion model in NOD/SCID (nonobese diabetic/severe combined Immunodeficient) mice. RESULTS: In ECMO patients, we observed a time-dependent decrease in platelet count starting 1 hour after device onset, with a mean drop of 7%, 35%, and 41% at 1, 24, and 48 hours post-ECMO initiation (P=0.00013, P<0.0001, and P<0.0001, respectively), regardless of the type of ECMO. This drop in platelet count was associated with a decrease in platelet GP Ibα expression (before: 47.8±9.1 versus 24 hours post-ECMO: 42.3±8.9 mean fluorescence intensity; P=0.002) and an increase in soluble GP Ibα plasma levels (before: 5.6±3.3 versus 24 hours post-ECMO: 10.8±4.1 µg/mL; P<0.0001). GP Ibα shedding was also observed ex vivo and was unaffected by (1) red blood cells, (2) the coagulation potential, (3) an antibody blocking VWF-GP Ibα interaction, (4) an antibody limiting VWF degradation, and (5) supraphysiological VWF plasma concentrations. In contrast, GP Ibα shedding was dependent on rheological conditions, with a 2.8-fold increase at high- versus low-flow rates. Platelets perfused at high-flow rates before being transfused to immunodeficient mice were eliminated faster in vivo with an accelerated clearance of GP Ibα-negative versus GP Ibα-positive platelets. CONCLUSIONS: ECMO-associated shear forces induce GP Ibα shedding and thrombocytopenia due to faster clearance of GP Ibα-negative platelets. Inhibiting GP Ibα shedding could represent an approach to reduce thrombocytopenia during ECMO.

Cerebral Microbleeds During Transcatheter Aortic Valve Replacement: A Prospective Magnetic Resonance Imaging Cohort.

BACKGROUND: Cerebral microbleeds (CMBs) have been observed in healthy elderly people undergoing systematic brain magnetic resonance imaging. The potential role of acute triggers on the appearance of CMBs remains unknown. We aimed to describe the incidence of new CMBs after transcatheter aortic valve replacement (TAVR) and to identify clinical and procedural factors associated with new CMBs including hemostatic measures and anticoagulation management. METHODS: We evaluated a prospective cohort of patients with symptomatic aortic stenosis referred for TAVR for CMBs (METHYSTROKE [Identification of Epigenetic Risk Factors for Ischemic Complication During the TAVR Procedure in the Elderly]). Standardized neurologic assessment, brain magnetic resonance imaging, and analysis of hemostatic measures including von Willebrand factor were performed before and after TAVR. Numbers and location of microbleeds on preprocedural magnetic resonance imaging and of new microbleeds on postprocedural magnetic resonance imaging were reported by 2 independent neuroradiologists blinded to clinical data. Measures associated with new microbleeds and postprocedural outcome including neurologic functional outcome at 6 months were also examined. RESULTS: A total of 84 patients (47% men, 80.9±5.7 years of age) were included. On preprocedural magnetic resonance imaging, 22 patients (26% [95% CI, 17%-37%]) had at least 1 microbleed. After TAVR, new microbleeds were observed in 19 (23% [95% CI, 14%-33%]) patients. The occurrence of new microbleeds was independent of the presence of microbleeds at baseline and of diffusion-weighted imaging hypersignals. In univariable analysis, a previous history of bleeding (P=0.01), a higher total dose of heparin (P=0.02), a prolonged procedure (P=0.03), absence of protamine reversion (P=0.04), higher final activated partial thromboplastin time (P=0.05), lower final von Willebrand factor high-molecular-weight:multimer ratio (P=0.007), and lower final closure time with adenosine-diphosphate (P=0.02) were associated with the occurrence of new postprocedural microbleeds. In multivariable analysis, a prolonged procedure (odds ratio, 1.22 [95% CI, 1.03-1.73] for every 5 minutes of fluoroscopy time; P=0.02) and postprocedural acquired von Willebrand factor defect (odds ratio, 1.42 [95% CI, 1.08-1.89] for every lower 0.1 unit of high-molecular-weight:multimer ratio; P=0.004) were independently associated with the occurrence of new postprocedural microbleeds. New CMBs were not associated with changes in neurologic functional outcome or quality of life at 6 months. CONCLUSIONS: One out of 4 patients undergoing TAVR has CMBs before the procedure and 1 out of 4 patients develops new CMBs. Procedural or antithrombotic management and persistence of acquired von Willebrand factor defect were associated with the occurrence of new CMBs. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT02972008.

Balloon aortic valvuloplasty for severe aortic stenosis before urgent non-cardiac surgery.

BACKGROUND: Balloon aortic valvuloplasty (BAV) has been proposed as a therapeutic option in patients suffering from severe aortic stenosis (SAS) who need urgent non-cardiac surgery (NCS). Whether this strategy is better than medical therapy in this very specific population is unknown. AIMS: We aimed to evaluate the clinical benefit of an invasive strategy (IS) with preoperative BAV in patients with SAS requiring urgent NCS. METHODS: From 2011 to 2019, a registry conducted in two centres included 133 patients with SAS undergoing urgent NCS, of whom 93 underwent preoperative BAV (IS) and 40 a conservative strategy (CS) without BAV. All analyses were adjusted for confounding using inverse probability of treatment weighting (IPTW) (10 clinical and anatomical variables). RESULTS: The primary outcome was MACE at one-month follow-up after NCS including mortality, heart failure, and other cardiovascular outcomes. In patients managed conservatively, occurrence of MACE was 20.0% (n=8) and death was 10.0% (n=4) at 1 month. In patients undergoing BAV, the occurrence of MACE was 20.4% (n=19) and death was 5.4% (n=5) at 1 month. Among patients undergoing conservative management, all events were observed after NCS while, in patients undergoing BAV, 12.9% (n=12) had events between BAV and NCS including 3 deaths, and 7.5% (n=7) had events after NCS including 2 deaths. In IPTW propensity analyses, the incidence of the primary outcome (20.4% vs 20.0%; OR 0.93, 95% CI: 0.38-2.29) and three-month survival (89.2% vs 90.0%; IPTW-adjusted HR 0.90, 95% CI: 0.31-2.60) were similar in both groups. CONCLUSIONS: Patients with SAS managed conservatively before urgent NCS are at high risk of events. A systematic invasive strategy using BAV does not provide a significant improvement in clinical outcome.

Myocardial Infarction incidence during national lockdown in two French provinces unevenly affected by COVID-19 outbreak: An observational study.

BACKGROUND: A reduction of admission for MI has been reported in most countries affected by COVID-19. No clear explanation has been provided. METHODS: To report the incidence of myocardial infarction (MI) admission during COVID-19 pandemic and in particular during national lockdown in two unequally affected French provinces (10-million inhabitants) with a different media strategy, and to describe the magnitude of MI incidence changes relative to the incidence of COVID-19-related deaths. A longitudinal study to collect all MIs from January 1 until May 17, 2020 (study period) and from the identical time period in 2019 (control period) was conducted in all centers with PCI-facilities in northern "Hauts-de-France" province and western "Pays-de-la-Loire" Province. The incidence of COVID-19 fatalities was also collected. FINDINGS: In "Hauts-de-France", during lockdown (March 18-May 10), 1500 COVID-19-related deaths were observed. A 23% decrease in MI-IR (IRR=0.77;95%CI:0.71-0.84, p<0.001) was observed for a loss of 272 MIs (95%CI:-363,-181), representing 18% of COVID-19-related deaths. In "Pays-de-la-Loire", 382 COVID-19-related deaths were observed. A 19% decrease in MI-IR (IRR=0.81; 95%CI=0.73-0.90, p<0.001) was observed for a loss of 138 MIs (95%CI:-210,-66), representing 36% of COVID-19-related deaths. While in "Hauts-de-France" the MI decline started before lockdown and recovered 3 weeks before its end, in "Pays-de-la-Loire", it started after lockdown and recovered only by its end. In-hospital mortality of MI patients was increased during lockdown in both provinces (5.0% vs 3.4%, p=0.02). INTERPRETATION: It highlights one of the potential collateral damages of COVID-19 outbreak on cardiovascular health with a dramatic reduction of MI incidence. It advocates for a careful and weighted communication strategy in pandemic crises. FUNDING: The study was conducted without external funding.

Feasibility and safety of transfemoral transcatheter aortic valve implantation performed with a percutaneous coronary intervention-like approach.

BACKGROUND: Transfemoral percutaneous transcatheter aortic valve implantation (TF-TAVI) is a safe, reproducible and established procedure, mainly performed under local anaesthesia, which is mostly administered and monitored by a dedicated anaesthesia team (regular approach). Our centre has developed a standardized pathway of care, and eligible patients are selected for a minimalist TF-TAVI, entirely managed by operators without the presence of the anaesthesia team in the operating room, like most interventional coronary procedures ("percutaneous coronary intervention-like" approach [PCI approach]). AIM: To compare the safety and efficacy of TF-TAVI performed with the PCI approach versus the regular approach. METHODS: The analysis population comprised all patients who underwent TF-TAVI with the PCI or regular approach in our institution from November 2016 to July 2019. The two co-primary endpoints were early safety composite and early efficacy composite at 30days as defined by the Valve Academic Research Consortium-2. The PCI (n=137) and Regular (n=221) approaches were compared using the propensity score based method of inverse probability of treatment weighting. RESULTS: No differences were observed after comparison of TAVI performed with the PCI or regular approach regarding the composite safety endpoint (7.3% vs. 11.3%; odds ratio 0.63, 95% confidence interval 0.37 to 1.07; P=0.086) or the composite efficacy endpoint (4.4% vs. 6.3%; odds ratio 0.78, 95% confidence interval 0.41 to 1.49; P=0.45). CONCLUSIONS: This study suggests that the efficacy and safety of TF-TAVI entirely managed by a PCI approach for selected patients are not different to those when TF-TAVI is performed with the attendance of a full anaesthesia care team. The PCI approach appears to be a safe and efficient clinical pathway, providing an appropriate and rational utilization of anaesthesiology resources, and could be used for the majority of TF-TAVI procedures.

Transcatheter Aortic Valve Replacement in Bicuspid Aortic Valve Stenosis.

After 15 years of successive randomized, controlled trials, indications for transcatheter aortic valve replacement (TAVR) are rapidly expanding. In the coming years, this procedure could become the first line treatment for patients with a symptomatic severe aortic stenosis and a tricuspid aortic valve anatomy. However, randomized, controlled trials have excluded bicuspid aortic valve (BAV), which is the most frequent congenital heart disease occurring in 1% to 2% of the total population and representing at least 25% of patients 80 years of age or older referred for aortic valve replacement. The use of a less invasive transcatheter therapy in this elderly population became rapidly attractive, and approximately 10% of patients currently undergoing TAVR have a BAV. The U.S. Food and Drug Administration and the "European Conformity" have approved TAVR for low-risk patients regardless of the aortic valve anatomy whereas international guidelines recommend surgical replacement in BAV populations. Given this progressive expansion of TAVR toward younger and lower-risk patients, heart teams are encountering BAV patients more frequently, while the ability of this therapy to treat such a challenging anatomy remains uncertain. This review will address the singularity of BAV anatomy and associated technical challenges for the TAVR procedure. We will examine and summarize available clinical evidence and highlight critical knowledge gaps regarding TAVR utilization in BAV patients. We will provide a comprehensive overview of the role of computed tomography scans in the diagnosis, and classification of BAV and TAVR procedure planning. Overall, we will offer an integrated framework for understanding the current role of TAVR in the treatment of bicuspid aortic stenosis and for guiding physicians in clinical decision-making.

Ultrasound Guidance to Reduce Vascular and Bleeding Complications of Percutaneous Transfemoral Transcatheter Aortic Valve Replacement: A Propensity Score-Matched Comparison.

Background Ultrasound (US) guidance provides the unique opportunity to control the puncture zone of the artery during transfemoral transcatheter aortic valve replacement and may decrease major vascular complications (VC) and life-threatening or major bleeding complications. This study aimed to evaluate the clinical impact of US guidance using a propensity score-matched comparison. Methods and Results US guidance was implemented as the default approach for all transfemoral transcatheter aortic valve replacement cases in our institution in June 2013. We defined 3 groups of consecutive patients according to the method of puncture (fluoroscopic/US guidance) and the use of a transcatheter heart valve. Patients in the US-guided second-generation group (Sapien XT [Edwards Lifesciences, Irvine, CA], Corevalve [Medtronic, Dublin, Ireland]) were successfully 1:1 matched with patients in the fluoroscope-guided second-generation group (n=95) with propensity score matching. In a second analysis we described the consecutive patients of the US-guided third-generation group (Evolut-R [Medtronic], Sapien 3 [Edwards Lifesciences], n=308). All vascular and bleeding complications were reduced in the US-guided second-generation group compared with the fluoroscope-guided second-generation group: VC (16.8% versus 6.3%; P=0.023); life-threatening or major bleeding (22.1% versus 6%; P=0.004); and VC related to vascular access (12.6% versus 4.2%; P=0.052). In the US-guided third-generation group the rates of major VC and life-threatening or major bleeding were 3.2% (95% CI, 1.6% to 5.9%) and 3.6% (95% CI, 1.8% to 6.3%). In the overall population (n=546), life-threatening or major bleeding was associated with a 1.7-fold increased mortality risk (P=0.02). Conclusions We demonstrated that US guidance effectively reduced VC and bleeding complications for transfemoral transcatheter aortic valve replacement and should be considered the standard puncture method. Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT02628509.

Real-Time Monitoring of von Willebrand Factor in the Catheterization Laboratory: The Seatbelt of Mini-Invasive Transcatheter Aortic Valve Replacement?

Significant paravalvular regurgitation (PVR) remains a relatively frequent (4% to 9%) and deleterious complication of transcatheter aortic valve replacement (TAVR), even with the latest generation of bioprosthesis. Although mini-invasive TAVR without general anesthesia or transesophageal echocardiography (TEE) is progressively becoming the predominant approach, identification and grading of PVR in the catheterization laboratory remain an important and challenging clinical issue. The authors discuss how a recently reported blood biomarker reflecting the von Willebrand factor activity, that is, the closure time with adenosine diphosphate, can be successfully applied during the TAVR procedure to detect and monitor PVR in real time, with an excellent negative predictive value. This point-of-care testing performed directly in the catheterization laboratory may improve the diagnosis of PVR and rationalize the decision of whether or not to perform corrective measures. They further discuss how such a test could be a substitute for the multimodal approach combining TEE, hemodynamics, and cine-angiography, and help to secure the transition to the mini-invasive approach and facilitate the expanding indications of less invasive procedures to lower-risk patients without jeopardizing procedural and clinical outcomes.

Urgent balloon aortic valvuloplasty in patients with cardiogenic shock related to severe aortic stenosis: time matters.

AIMS: The aim of the study was to assess the outcomes of balloon aortic valvuloplasty (BAV) as a rescue therapy in patients with cardiogenic shock (CS) related to severe aortic stenosis (AS). METHODS AND RESULTS: Forty-four consecutive patients, n=31 with hypotensive CS (HCS) and n=13 with non-hypotensive CS (NHCS) due to acutely decompensated severe AS, from two centres were treated with urgent BAV. The composite primary endpoint was mortality or recurrent CS at one-year follow-up. These patients (77.3±8.1 years old; 75% male) had a mean EuroSCORE II of 41.6±13.7%. One-month mortality was 47%. Twelve patients (27%) had either a staged TAVR (n=10) or surgical aortic valve replacement (SAVR) (n=2) with a median delay of 79 days after BAV: n=6 (19%) in the HCS subgroup and n=6 (46%) in the NHCS population (p=0.06). At one year, the rate of composite all-cause death or recurrent CS was 75% and significantly higher in the HCS subgroup (83% vs. 53%; p=0.03). Overall one-year mortality was 70% (n=31) with a trend for a better prognosis in NHCS patients (54% vs. 77%; p=0.09). Univariate predictive factors of the primary endpoint included preoperative dose of dobutamine >5 microg/kg/min (100% vs. 57%; p=0.001) and delayed BAV >48 hrs (90% vs. 59%; p=0.01). CONCLUSIONS: Despite the initial success of urgent BAV, morbidity and mortality of CS related to severe AS remain high and directly related to the time of the valvuloplasty. Performing BAV before or within 48 hours of starting inotropic agents appears to be key to survival.

Arterial Pulsatility and Circulating von Willebrand Factor in Patients on Mechanical Circulatory Support.

BACKGROUND: The main risk factor for bleeding in patients with continuous-flow mechanical circulatory support (CF-MCS) is the acquired von Willebrand factor (VWF) defect related to the high shear-stress forces developed by these devices. Although a higher bleeding rate has been reported in CF-MCS recipients who had reduced pulsatility, the relation between pulsatility and the VWF defect has never been studied. OBJECTIVES: The purpose of this study was to investigate the relation between pulsatility and VWF under CF-MCS. METHODS: We assessed the effect of 2 CF-MCS on VWF multimer degradation in a mock circulatory loop (model 1). Using these devices, we investigated in a dose-effect model (model 2) 3 levels of pulsatility in 3 groups of swine. In a cross-over model (model 3), we studied the effects of sequential changes of pulsatility on VWF. We reported the evolution of VWF multimerization in a patient undergoing serial CF-MCS and/or pulsatile-MCS. RESULTS: We demonstrated the proteolytic degradation of VWF multimers by high shear CF-MCS in a circulatory loop without pulsatility. We observed both in swine models and in a patient that the magnitude of the VWF degradation is modulated by the pulsatility level in the high shear-stress level condition, and that the restoration of pulsatility is a trigger for the endothelial release of VWF. CONCLUSIONS: We demonstrated that the VWF defect reflects the balance between degradation induced by the shear stress and the endothelial release of new VWF triggered by the pulsatility. This modulation of VWF levels could explain the relationship between pulsatility and bleeding observed in CF-MCS recipients. Preservation of pulsatility may be a new target to improve clinical outcomes of patients.