Thrombin Generation Is Associated With Extracellular Vesicle and Leukocyte Lipid Membranes in Atherosclerotic Cardiovascular Disease.

BACKGROUND: Clotting, leading to thrombosis, requires interactions of coagulation factors with the membrane aminophospholipids (aPLs) phosphatidylserine and phosphatidylethanolamine. Atherosclerotic cardiovascular disease (ASCVD) is associated with elevated thrombotic risk, which is not fully preventable using current therapies. Currently, the contribution of aPL to thrombotic risk in ASCVD is not known. Here, the aPL composition of circulating membranes in ASCVD of varying severity will be characterized along with the contribution of external facing aPL to plasma thrombin generation in patient samples. METHODS: Thrombin generation was measured using a purified factor assay on platelet, leukocyte, and extracellular vesicles (EVs) from patients with acute coronary syndrome (n=24), stable coronary artery disease (n=18), and positive risk factor (n=23) and compared with healthy controls (n=24). aPL composition of resting/activated platelet and leukocytes and EV membranes was determined using lipidomics. RESULTS: External facing aPLs were detected on EVs, platelets, and leukocytes, elevating significantly following cell activation. Thrombin generation was higher on the surface of EVs from patients with acute coronary syndrome than healthy controls, along with increased circulating EV counts. Thrombin generation correlated significantly with externalized EV phosphatidylserine, plasma EV counts, and total EV membrane surface area. In contrast, aPL levels and thrombin generation from leukocytes and platelets were not impacted by disease, although circulating leukocyte counts were higher in patients. CONCLUSIONS: The aPL membrane of EV supports an elevated level of thrombin generation in patient plasma in ASCVD. Leukocytes may also play a role although the platelet membrane did not seem to contribute. Targeting EV formation/clearance and developing strategies to prevent the aPL surface of EV interacting with coagulation factors represents a novel antithrombotic target in ASCVD.

Phosphatidylthreonine is a procoagulant lipid detected in human blood and elevated in coronary artery disease.

Aminophospholipids (aPL) such as phosphatidylserine are essential for supporting the activity of coagulation factors, circulating platelets, and blood cells. Phosphatidylthreonine (PT) is an aminophospholipid previously reported in eukaryotic parasites and animal cell cultures, but not yet in human tissues. Here, we evaluated whether PT is present in blood cells and characterized its ability to support coagulation. Several PT molecular species were detected in human blood, washed platelets, extracellular vesicles, and isolated leukocytes from healthy volunteers using liquid chromatography-tandem mass spectrometry. The ability of PT to support coagulation was demonstrated in vitro using biochemical and biophysical assays. In liposomes, PT supported prothrombinase activity in the presence and absence of phosphatidylserine. PT nanodiscs strongly bound FVa and lactadherin (nM affinity) but poorly bound prothrombin and FX, suggesting that PT supports prothrombinase through recruitment of FVa. PT liposomes bearing tissue factor poorly generated thrombin in platelet poor plasma, indicating that PT poorly supports extrinsic tenase activity. On platelet activation, PT is externalized and partially metabolized. Last, PT was significantly higher in platelets and extracellular vesicle from patients with coronary artery disease than in healthy controls. In summary, PT is present in human blood, binds FVa and lactadherin, supports coagulation in vitro through FVa binding, and is elevated in atherosclerotic vascular disease. Our studies reveal a new phospholipid subclass, that contributes to the procoagulant membrane, and may support thrombosis in patients at elevated risk.

Wearables in Wales: Entering clinical practice through the backdoor?

The number of people using wearable technology such as smartwatches and fitness trackers is increasing. Many of these devices can alert the user to a potential arrhythmia such as atrial fibrillation. We aimed to assess potential changes to cardiology practice resulting from their use. An online questionnaire consisting of 12 questions was created and distributed to all consultant cardiologists in Wales. 25 of 102 participants replied, with 92% of these using consumer wearable technology to diagnose atrial fibrillation either 'often' or 'sometimes'. One in four cardiologists received new referrals relating to wearable technology at least weekly. The results demonstrate that cardiologists across Wales are using data from wearable technology in the diagnosis and management of cardiac conditions in the absence of formal guidance. Standardisation of guidelines and pathways is needed to support patients and clinicians and avoid the introduction of wearables through the unregulated backdoor.

Optimizing heart failure pathways to enhance patient care: the Program to Optimize Heart Failure Patient Pathways (PRO-HF).

AIMS: Many European healthcare providers struggle to adopt multidisciplinary, integrated care pathways for people with heart failure (HF) as recommended by the European Society of Cardiology. PRO-HF (Program to Optimize Heart Failure Patient Pathways) was developed to help clinicians identify strengths, gaps, and shortcomings in their HF pathways and support tailored interventions to optimize pathways and enhance patient care. We report initial findings from baseline assessments of HF pathway characteristics and challenges from 10 hospitals in six European countries (France, Ireland, Portugal, Spain, The Netherlands, and United Kingdom). METHODS AND RESULTS: Baseline assessments were holistic appraisals of full HF services to calibrate current status and development needs and assist management teams in prioritizing improvement projects. Assessments were performed using a comprehensive checklist of measures covering the HF patient journey from diagnosis to ongoing follow-up. These included a digital survey sent to full HF care teams and one-to-one interviews. The digital survey focused on four key areas (HF outpatient clinic; remote patient management; efficient device implantation and inpatient pathways; and network maximization) and 16 dimensions of excellence. Priority areas and themes for action identified in baseline assessments were (i) provision of HF specialist care; (ii) data capture and analysis; (iii) institutional care protocols; (iv) hospital-wide strategies; and (v) multidisciplinary teams (MDTs). Suboptimal specialist care of emergency inpatients was an issue at all hospitals and prioritized at 8/10. Availability and accessibility of data on patients, activities, and outcomes was an issue at all hospitals and prioritized by 4/10. A lack of clear protocols, templates, and tools for some HF activities created variability in patient care (e.g., HF specialist consultations, diagnostic testing, follow-up appointments, medications, and device eligibility) and inefficient use of clinician time. This made it difficult to initiate new technologies (e.g., remote patient monitoring) due to the risk of overburdening staff. MDTs were frequently understaffed. Multiple interventions were identified to address gaps and shortcomings that could be tailored to specific needs of individual hospitals (e.g., inpatient pathway optimization, creation/optimization of HF outpatient clinics, development of an HF performance dashboard, enhancement of protocol adherence, streamlining cardiac resynchronisation therapy pathways, and MDT coordination). CONCLUSIONS: PRO-HF provides a valuable opportunity to identify gaps and significant shortcomings in HF pathways in European hospitals. Preliminary findings from hospitals that have initiated suggested changes to address these challenges are encouraging, though longer-term follow-up from more hospitals is needed to confirm the impact of PRO-HF on HF pathway optimization and patient care.