Pragmatic observations from a post-COVID-19 cardiac evaluation register: prevalence of cardiological alterations from a basic diagnostic sequence and contribution of the clinical hystory

Introduction

The prevalence of cardiological sequelae in patients recovered from COVID-19 varies in different reports. This may be due to the population diversity studied or to the complementary methods on which the diagnosis was based.

Objective

1) To determine the prevalence of “de novo” cardiological alterations (DN) in the population recovered from COVID-19 using a basic cardiological evaluation sequence. 2) To evaluate the contribution of the clinical history (CH) in the detection of DN.

Methods

Patients (pts) with COVID-19, PCR (+) were included. The pts attended an ambulatory consultation office at least 30 days after discharge from COVID-19. The evaluation was performed in a stepwise manner: first Interview: CH, physical examination (PE), and EKG; second Interview: routine laboratory test, C-reactive protein, echocardiogram and cardiac biomarkers. Other complementary studies (Holter, RMI, CCG) were requested according to previous findings. The diagnosis of DN (by PE, EKG or echocardiogram, alone or with the addition of other methods) was defined as the appearance of cardiological alterations in patients with no pre-existing known heart disease or the progression of a known cardiac disease. The prevalence of DN is described. Sensitivity, specificity and predictive value of CH for DN are reported.

Results

A total of 246 pts were evaluated with the first interview (age: 52±13 years; women: 47.8%; caucasian: 60.6%; overweight: 79%; some pathological history: 71.5%; previous heart disease: 15.4%; hospitalization during the acute phase of COVID: 78.8%; mild Covid: 37%, moderate: 39%, severe: 24%; time between discharge and post-COVID evaluation: 68±42 days). DN were detected in 62 pts: rhythm disturbances: 41 (sinus tachycardia: 23 (18 isolated), sinus bradycardia: 3, supraventricular arrhythmia: 6, ventricular arrhythmia: 14); conduction disturbance: 10, ventricular dysfunction: 20 (12 de novo, 8 progression). Specific diagnoses: myocarditis: 6, coronary artery disease: 5, acute mitral insufficiency: 1. In 16 pts (6.5%) DN had clinical relevance. Six of them (2.4%) required hospitalization. In previously healthy pts with mild COVID, only rhythm disorders were detected in 3 pts. Se, Sp and PV of the CH is shown in Table 1. Eighteen Holter monitoring tests (5 +), 9 MRIs (5 +), 4 CCGs (2 +) were performed.

Conclusions

1) Using a basic cardiac diagnostic sequence, at least 30 days after discharge, a quarter of post-COVID patients had “de novo” cardiological findings. However, a small percentage became clinically relevant. The causal relationship of DN with COVID-19 cannot be unequivocally asserted. Previously healthy patients have low prevalence of cardiac findings detected with a basic diagnostic sequence.

2) The data obtained from the clinical history have a low positive predictive value.

Funding Acknowledgement

Type of funding sources: None.

The Serine/Threonine Protein Phosphatase 2A (PP2A) Regulates Syk Activity in Human Platelets

Distinct membrane receptors activate platelets by Src-family-kinase (SFK)-, immunoreceptor-tyrosine-based-activation-motif (ITAM)-dependent stimulation of spleen tyrosine kinase (Syk). Recently, we reported that platelet activation via glycoprotein (GP) VI or GPIbα stimulated the well-established Syk tyrosine (Y)-phosphorylation, but also stoichiometric, transient protein kinase C (PKC)-mediated Syk serine(S)297 phosphorylation in the regulatory interdomain-B, suggesting possible feedback inhibition. The transient nature of Syk S297 phosphorylation indicated the presence of an unknown Syk pS297 protein phosphatase. In this study, we hypothesize that the S-protein phosphatase 2A (PP2A) is responsible for Syk pS297 dephosphorylation, thereby affecting Syk Y-phosphorylation and activity in human washed platelets. Using immunoblotting, we show that specific inhibition of PP2A by okadaic acid (OA) alone leads to stoichiometric Syk S297 phosphorylation, as analyzed by Zn²⁺-Phos-tag gels, without affecting Syk Y-phosphorylation. Pharmacological inhibition of Syk by PRT060318 or PKC by GF109203X only minimally reduced OA-induced Syk S297 phosphorylation. PP2A inhibition by OA preceding GPVI-mediated platelet activation induced by convulxin extended Syk S297 phosphorylation but inhibited Syk Y-phosphorylation. Our data demonstrate a novel biochemical and functional link between the S-protein phosphatase PP2A and the Y-protein kinase Syk in human platelets, and suggest that PP2A represents a potential enhancer of GPVI-mediated Syk activity caused by Syk pS297 dephosphorylation.

CD36-fibrin interaction propagates FXI-dependent thrombin generation of human platelets

Thrombin converts fibrinogen to fibrin and activates blood and vascular cells in thrombo-inflammatory diseases. Platelets are amplifiers of thrombin formation when activated by leukocyte- and vascular cell-derived thrombin. CD36 on platelets acts as sensitizer for molecules with damage-associated molecular patterns, thereby increasing platelet reactivity. Here, we investigated the role of CD36 in thrombin-generation on human platelets, including selected patients with advanced chronic kidney disease (CKD). Platelets deficient in CD36 or blocked by anti-CD36 antibody FA6.152 showed impaired thrombin generation triggered by thrombin in calibrated automated thrombography. Using platelets with congenital function defects, blocking antibodies, pharmacological inhibitors, and factor-depleted plasma, CD36-sensitive thrombin generation was dependent on FXI, fibrin, and platelet signaling via GPIbα and SFKs. CD36-deficiency or blocking suppressed thrombin-induced platelet αIIbβ3 activation, granule exocytosis, binding of adhesion proteins and FV, FVIII, FIX, FX, but not anionic phospholipid exposure determined by flow cytometry. CD36 ligated specifically soluble fibrin, which recruited distinct coagulation factors via thiols. Selected patients with CKD showed elevated soluble fibrin plasma levels and enhanced thrombin-induced thrombin generation, which was normalized by CD36 blocking. Thus, CD36 is an important amplifier of platelet-dependent thrombin generation when exposure of anionic phospholipids is limited. This pathway might contribute to hypercoagulability in CKD.

P2788First argentine national registry of echocardiograpphic aortic dimensions: body surface area, age and ethnicity are determinants of aortic dimensions

Background

Transthoracic echocardiography (TTE) remains the screening tool of choice for thoracic aorta (TA) dilatation. Differences in TA diameters (TAD) according to gender (G), age (A) and body surface area (BSA) have been previously reported. However, these reports are limited by a small sample size, different measurement sites or heterogeneous cohorts. There is scarce data on the influence of ethnicitiy on TAD. Moreover, surgery indication for TA aneurysms is still based mainly on absolute TAD with no reference to G, A or BSA.

Purpose

We designed a prospective nationwide multicenter registry to determine the normal range of TAD at all TA segments in healthy adults of both G and their correlations with A, ethnicity and BSA.

Methods

Healthy adult individuals without cardiovascular risk factors, TA aneurysm, aortic valve disease, cardiac surgery or genetic aortopathies were recruited from 53 centers in Argentina. TTEs were acquired and measured following standard protocols based on EACVI/ASE Guidelines. TAD were measured at six levels: annulus, sinuses of Valsalva, sinotubular junction, tubular ascending aorta, aortic arch and proximal descending aorta. Annulus was measured at mid-systole (inner to inner edge method) and all other at end-diastole (leading to leading edge).

Multiple linear regression models were conducted to obtain coefficients of determination (R2) and 95% prediction intervals. We defined upper normal limits (95th percentile) for 4 age categories, both G and analyzed differences according to ethnicity.

Results

The MATEAR registry included 905 healthy adult patients (mean age: 38.3±13 years, 508 women, BSA: 1.8±0.2 m2). 529 (58.4%) were caucasian and 332 (36.6%) native-american, representative of the ethnic composition of Argentine population.

Pooled data showed a positive correlation between all TAD and A or BSA (p<0.001), similar in both G. Women had smaller absolute TAD due to their lower BSA. Nomograms were obtained for 4 age categories to predict TAD from BSA with no need of G distinction. Native americans showed significatly lower absolute and indexed TAD than caucasian (p<0.01) from annulus to isthmus.

TAD differences according to ethnicity

Conclusions

While age and BSA were significant determinants of aortic dimensions at six levels, we have also detected differences in TAD according to ethnicity, suggesting normative values should also be defined for each ethnic group. We propose nomograms of indexed TAD for different age and ethnic groups without G distinction.

cAMP- and cGMP-elevating agents inhibit GPIbα-mediated aggregation but not GPIbα-stimulated Syk activation in human platelets

Background

The glycoprotein (GP) Ib-IX-V complex is a unique platelet plasma membrane receptor, which is essential for platelet adhesion and thrombus formation. GPIbα, part of the GPIb-IX-V complex, has several physiological ligands such as von Willebrand factor (vWF), thrombospondin and distinct coagulation factors, which trigger platelet activation. Despite having an important role, intracellular GPIb-IX-V signaling and its regulation by other pathways are not well defined. Our aim was to establish the intracellular signaling response of selective GPIbα activation in human platelets, in particular the role of the tyrosine kinase Syk and its regulation by cAMP/PKA and cGMP/PKG pathways, respectively. We addressed this using echicetin beads (EB), which selectively bind to GPIbα and induce platelet aggregation.

Methods

Purified echicetin from snake Echis carinatus venom was validated by mass spectrometry. Washed human platelets were incubated with EB, in the presence or absence of echicetin monomers (EM), Src family kinase (SFK) inhibitors, Syk inhibitors and the cAMP- and cGMP-elevating agents iloprost and riociguat, respectively. Platelet aggregation was analyzed by light transmission aggregometry, protein phosphorylation by immunoblotting. Intracellular messengers inositolmonophosphate (InsP1) and Ca²⁺_i were measured by ELISA and Fluo-3 AM/FACS, respectively.

Results

EB-induced platelet aggregation was dependent on integrin α_IIbβ₃ and secondary mediators ADP and TxA₂, and was antagonized by EM. EB stimulated Syk tyrosine phosphorylation at Y352, which was SFK-dependent and Syk-independent, whereas Y525/526 phosphorylation was SFK-dependent and partially Syk-dependent. Furthermore, phosphorylation of both Syk Y352 and Y525/526 was completely integrin α_IIbβ₃-independent but, in the case of Y525/526, was partially ADP/TxA₂-dependent. Syk activation, observed as Y352/ Y525/Y526 phosphorylation, led to the phosphorylation of direct substrates (LAT Y191, PLCγ2 Y759) and additional targets (Akt S473). PKA/PKG pathways inhibited EB-induced platelet aggregation and Akt phosphorylation but, surprisingly, enhanced Syk and LAT/PLCγ2 tyrosine phosphorylation. A similar PKA/PKG effect was confirmed with convulxin−/GPVI-stimulated platelets. EB-induced InsP1 accumulation/InsP3 production and Ca²⁺-release were Syk-dependent, but only partially inhibited by PKA/PKG pathways.

Conclusion

EB and EM are specific agonists and antagonists, respectively, of GPIbα-mediated Syk activation leading to platelet aggregation. The cAMP/PKA and cGMP/PKG pathways do not inhibit but enhance GPIbα−/GPVI-initiated, SFK-dependent Syk activation, but strongly inhibit further downstream responses including aggregation. These data establish an important intracellular regulatory network induced by GPIbα.

Graphical abstract

Electronic supplementary material

The online version of this article (10.1186/s12964-019-0428-1) contains supplementary material, which is available to authorized users.

The Direct Thrombin Inhibitors Dabigatran and Lepirudin Inhibit GPIbα-Mediated Platelet Aggregation

The direct thrombin inhibitor (DTI) dabigatran is a non-vitamin K antagonist oral anticoagulant for the prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation. In addition to its anti-thrombotic efficacy, dabigatran has been suggested to exert some pro-thrombotic effect due to fostering the ligation of thrombin to its high affinity platelet receptor glycoprotein (GP) Ibα in patients with atrial fibrillation. On the other hand, we provided evidence that a member of another class of DTIs, lepirudin, stimulates the inhibitory cyclic guanosine monophosphate (cGMP)/soluble guanylate cyclase pathway in human platelets. Here, we investigated the effect of lepirudin and dabigatran spiked to platelets from healthy volunteers on GPIbα-mediated platelet aggregation and agglutination. Ristocetin/von Willebrand factor (vWF)-induced aggregation of platelets in the presence or absence of plasma was significantly inhibited by lepirudin, dabigatran and D-phenylalanyl-L-prolyl-L-arginine chloromethyl ketone (PPACK). However, ristocetin/vWF-mediated platelet agglutination and binding of vWF to platelets were not affected by the DTIs. The anti-aggregatory effect was confirmed by using the GPIbα-specific agonist echicetin beads for human and murine platelets. DTIs diminished echicetin beads-induced Syk Y352 phosphorylation (used here as readout for an early signal occurring during echicetin-induced platelet aggregation), but did not inhibit adenosine diphosphate- or thromboxane A2-induced platelet aggregation. Thrombin was not generated in response to ristocetin/vWF or echicetin beads and therefore did not explain the inhibitory effect of the DTIs. Therapeutic concentration of lepirudin and dabigatran did not affect significantly platelet vasodilator-stimulated phosphoprotein S239 phosphorylation or cGMP and cyclic adenosine monophosphate levels. These data suggest that the DTIs, lepirudin and dabigatran, impair platelet activation measured during platelet aggregation induced by ristocetin/vWF or echicetin beads.

Effects of the NO/soluble guanylate cyclase/cGMP system on the functions of human platelets

Platelets are circulating sentinels of vascular integrity and are activated, inhibited, or modulated by multiple hormones, vasoactive substances or drugs. Endothelium- or drug-derived NO strongly inhibits platelet activation via activation of the soluble guanylate cyclase (sGC) and cGMP elevation, often in synergy with cAMP-elevation by prostacyclin. However, the molecular mechanisms and diversity of cGMP effects in platelets are poorly understood and sometimes controversial. Recently, we established the quantitative human platelet proteome, the iloprost/prostacyclin/cAMP/protein kinase A (PKA)-regulated phosphoproteome, and the interactions of the ADP- and iloprost/prostacyclin-affected phosphoproteome. We also showed that the sGC stimulator riociguat is in vitro a highly specific inhibitor, via cGMP, of various functions of human platelets. Here, we review the regulatory role of the cGMP/protein kinase G (PKG) system in human platelet function, and our current approaches to establish and analyze the phosphoproteome after selective stimulation of the sGC/cGMP pathway by NO donors and riociguat. Present data indicate an extensive and diverse NO/riociguat/cGMP phosphoproteome, which has to be compared with the cAMP phosphoproteome. In particular, sGC/cGMP-regulated phosphorylation of many membrane proteins, G-proteins and their regulators, signaling molecules, protein kinases, and proteins involved in Ca²⁺ regulation, suggests that the sGC/cGMP system targets multiple signaling networks rather than a limited number of PKG substrate proteins.

Prompts to encourage appointment attendance for people with serious mental illness

BACKGROUND

Prompts to encourage attendance at clinics are often used in day-to-day practice by diligent carers of people with mental health problems. These may take the form of telephone prompting, financial incentives or issuing a copy of the referral letter to the appointee.

OBJECTIVES

To estimate the effects of simple prompting by professional carers to encourage attendance at clinics for those with serious mental illness.

SEARCH STRATEGY

Methodical searches of Biological Abstracts (1985-2000), CINAHL (1982-2000), Cochrane Schizophrenia Group's Register (June 2000), Cochrane Library (Issue 2, 2000), EMBASE (1980-2000), MEDLINE (1966-2000) and PsycLIT (1887-2000) were undertaken. These were supplemented by searching of reference lists, personal contact and hand searching of high yield journals.

SELECTION CRITERIA

All relevant randomised (or quasi-randomised) studies comparing the addition of 'prompts' to standard care for those with serious mental illnesses such as schizophrenia. Prompts had the stated purpose of encouraging attendance or contact with mental health teams and could be text-based, electronic, by telephone call, by personal visit, or could employ financial or other rewards.

DATA COLLECTION AND ANALYSIS

Studies and data were independently selected and extracted. For homogeneous dichotomous data the random effects relative risk (RR), the 95% confidence intervals (CI) and, where appropriate, the number needed to treat (NNT) were calculated on an intention-to-treat basis. For continuous data the reviewers calculated weighted mean differences.

MAIN RESULTS

Only three relevant trials were identified (total n=597). It is not clear whether there is any real difference between attendance of those prompted by telephone one or two days before the appointment, and those given the standard appointment management system (2 trials, n=457, RR missed appointment 0.84 CI 0.7 to 1.1). Text-based prompts, a few days before the appointment day, did increase clinic attendance when compared with no prompt (2 trials, n=200, RR missed appointment 0.6 CI 0.4 to 0.9, NNT 6 CI 2 to 14). Only one small study (n=61) reported data on the combination of telephone and text-based prompts versus no prompt (RR missed appointments 0.7 CI 0.4 to 1.2). When telephone prompts were compared with text-based prompts (1 trial, n=75), the latter, in the form of an 'orientation statement' (a short paragraph, taking about 30 seconds to read, explaining the programme of care, the fee system, and providing gentle encouragement) may be somewhat more effective than the telephone prompt (RR missed appointments 1.9 CI 0.98 to 3.8). One last study (n=120) compared a standard letter prompt with a letter 'orientation statement'. Overall, results tended to favour the orientation statement approach rather than the simple letter prompting attendance but the results did not reach conventional levels of statistical significance (RR missed appointments 1.6 CI 0.9 to 2.9).

REVIEWER'S CONCLUSIONS

There is evidence that a simple prompt to attend clinic, very close to the time of the appointment may encourage attendance, and a simple orientation-type letter, 24 hours before the clinic appointment, may be more effective than a telephone prompt. This simple intervention could be a more cost effective means of encouraging compliance at first attendance, but supplementing these data with the results of large, well designed, conducted and reported randomised studies would be desirable.