Proneness to Formation of Tight and Rigid Fibrin Gel Structures in Men with Myocardial Infarction at a Young Age

The native fibrin gel structure formed in vitro from plasma samples was examined by liquid permeation of hydrated fibrin gel networks in 38 unselected men who had suffered a myocardial infarction before the age of 45 years and in 88 age-matched population-based control men. Both the fibrin gel porosity (permeability coefficient, Ks) and the calculated fiber mass-length ratio varied considerably within the two groups, but were generally lower in the patients. Ks was 8.3 ± 5.2 cm2 × 109 (mean ± SD) in the patient group and 12.5 ± 5.7cm2 × 109 among controls (p <0.001). The corresponding figures for fiber mass-length ratio were 13.1 ± 7.7 and 16.5 ± 7.5 Dalton/ cm × 10−13, respectively (p <0.01). Around 50% of the patients had Ks values below the 10th percentile of the control group. A strong inverse correlation was seen between plasma plasminogen activator inhibitor-1 (PAI-1) activity and Ks (r = -0.603, p <0.001) or fiber mass-length ratio (r = -0.565, p <0.001) in the patient group. Corresponding weaker associations of PAI-1 with fibrin gel properties were also present in the control group. In addition, inverse relationships of very low density lipoprotein (VLDL) triglyceride concentrations to Ks (r = -0.362, p <0.001) and fiber mass-length ratio (r = -0.283, p <0.01) were found among the controls. Proneness to formation of tight and rigid fibrin gel networks with abnormal architecture in vitro is in vivo associated with myocardial infarction at a young age. Impaired fibrinolytic function secondary to a raised plasma PAI-1 activity level is associated with abnormal fibrin gel structure.

Prognosis in relation to high-sensitivity cardiac troponin T levels in patients with myocardial infarction and non-obstructive coronary arteries

BACKGROUND

Myocardial infarction (MI) with non-obstructive coronary arteries (MINOCA) is a recently recognized condition where biomarkers and prognosis are less well studied than in MI with obstructive coronary artery disease (MI-CAD). We therefore aimed to investigate the one-year prognostic value of high-sensitivity cardiac troponin T (hs-cTnT) levels in MINOCA in comparison to MI-CAD.

METHODS

In this registry-based cohort study, we used data from patients with a discharge diagnosis of MI, admitted between 2009 and 2013 to Swedish hospitals using the hs-cTnT assay. Only patients without previously known coronary artery disease were considered. Patients with and without coronary stenosis >50% were regarded to have MI-CAD and MINOCA, respectively. Assessed outcomes included all-cause mortality, cardiovascular (CV) mortality and major CV events (MACE), defined as the composite of CV death or admissions for non-fatal MI, heart failure (HF) or ischemic stroke.

RESULTS

The study cohort consisted of 1639 MINOCA and 17,304 MI-CAD patients. In adjusted analyses, hs-cTnT (ln) in MINOCA patients predicted all-cause mortality (HR 1.32 [95% CI 1.11-1.56]), CV mortality (HR 2.11 [95% CI 1.51-2.96]) and MACE (HR 1.44 [95% CI 1.20-1.72]). Hs-cTnT (ln) also predicted readmissions for HF (HR 1.51 [95% CI 1.51-2.96]) but not non-fatal MI or stroke. Interaction analyses suggested that hs-cTnT (ln) was at least as prognostic in patients with MINOCA compared to MI-CAD.

CONCLUSIONS

Hs-cTnT levels in MINOCA patients are strong and independent predictors of adverse outcome. Consideration of hs-cTnT levels is important for risk assessment of MINOCA patients.

Abstract 652: MicroRNA-29b Mediates the Chronic Inflammatory Response in Radiotherapy-induced Vascular Disease

Radiotherapy is an established therapeutic method in many different cancer types. Its success raises a new problem, namely radiotherapy-induced vascular disease (vRTx), which typically manifests as coronary disease, heart failure or carotid stenosis. A chronic inflammatory response likely underlies vRTx, involving complex processes, such as vascular smooth muscle cell de-differentiation, oxidative stress, and ECM remodeling. These processes are tightly regulated and thus far difficult to influence therapeutically. In other diseases, a set of microRNAs (miRs) is known to orchestrate these processes. We hypothesized that they similarly could play a role in vRTx and be targets for treatment or prevention of the disease.

We performed qRT-PCR screening of 11 pre-selected miRs, which identified miR-29b as significantly decreased in irradiated arteries collected from patients undergoing free tissue transfer reconstruction, compared with non-irradiated arteries from the same patient (n=15). In a vascular biology context, miR-29b is known as inhibitor of collagen- and ECM associated mRNA targets, and has been shown to play a detrimental role in aneurysm disease and advanced atherosclerotic lesions.

Consistent with human tissue data, vascular smooth muscle and endothelial cells in vitro receiving two radiation doses of 2 Gy, showed decreased miR-29b upon 24 hours after exposure. In these irradiated SMCs, miR-29b induction reduced soluble collagen levels, while inhibition further increased them.

Array-based tissue gene expression analysis showed that Pentraxin-3 (PTX) and dipeptidyl-peptidase 4 (DPP4), both targets of miR-29b and pivotal in inflammation and adverse wound healing, were downregulated in the same patient cohort. Carotid arteries of Apoe -/- mice treated with miR-29b mimic, 24h before and 24h after irradiation (14 Gy to the upper chest and neck), displayed a downward trend (non-significant) in Ptx3 and Dpp4 gene expression.

Our results suggest that miR-29b overexpression therapy could have a place in the prevention of vRTx. To further strengthen this conclusion, additional Apoe -/- mice irradiation experiments are currently ongoing, to further establish PTX3 and DPP4 as mediators of anti-inflammatory and anti-fibrotic strategies.

Supplemental oxygen therapy does not affect the systemic inflammatory response to acute myocardial infarction

BACKGROUND

Oxygen therapy has been used routinely in normoxemic patients with suspected acute myocardial infarction (AMI) despite limited evidence supporting a beneficial effect. AMI is associated with a systemic inflammation. Here, we hypothesized that the inflammatory response to AMI is potentiated by oxygen therapy.

METHODS

The DETermination of the role of Oxygen in suspected Acute Myocardial Infarction (DETO2X-AMI) multicentre trial randomized patients with suspected AMI to receive oxygen at 6 L min^-1 for 6-12 h or ambient air. For this prespecified subgroup analysis, we recruited patients with confirmed AMI from two sites for evaluation of inflammatory biomarkers at randomization and 5-7 h later. Ninety-two inflammatory biomarkers were analysed using proximity extension assay technology, to evaluate the effect of oxygen on the systemic inflammatory response to AMI.

RESULTS

Plasma from 144 AMI patients was analysed whereof 76 (53%) were randomized to oxygen and 68 (47%) to air. Eight biomarkers showed a significant increase, whereas 13 were decreased 5-7 h after randomization. The inflammatory response did not differ between the two treatment groups neither did plasma troponin T levels. After adjustment for increase in troponin T over time, age and sex, the release of inflammation-related biomarkers was still similar in the groups.

CONCLUSIONS

In a randomized controlled setting of normoxemic patients with AMI, the use of supplemental oxygen did not have any significant impact on the early release of systemic inflammatory markers.

Lack of genetic susceptibility in takotsubo cardiomyopathy: a case-control study

BACKGROUND

Takotsubo cardiomyopathy (TCM), also known as "broken heart syndrome", is a type of heart failure characterized by transient ventricular dysfunction in the absence of obstructive coronary lesions. Although associated with increased levels of catecholamines, pathophysiological mechanisms are unknown. Relapses and family heritability indicate a genetic predisposition. Several small studies have investigated associations between three different loci; the β1-adrenic receptor (ADRB1), G-protein-coupled receptor kinase 5 (GRK5), Bcl-associated athanogene 3 (BAG3) and TCM but no consensus has been reached.

METHODS

Participants were recruited using the Swedish Coronary Angiography and Angioplasty Register (SCAAR). TCM patients without coronary artery disease (CAD)(n = 258) were identified and age- and sex-matched subjects with (n = 164) and without (n = 243) CAD were selected as controls. DNA was isolated from saliva and genotyped for candidate single nucleotide polymorphisms in the ADRB1, GRK5 and BAG3 genes. Allele frequencies and Odds Ratios (OR) with 95% Confidence Intervals (CI) for the investigated polymorphisms were compared, respectively calculated for TCM patients and controls.

RESULTS

There were no differences in allele frequencies between TCM patients and controls. OR (CI) for TCM patients having at least one minor allele using controls as reference were 1.07 (0.75-1.55) for ADRB1, 0.45 (0.11-1.85) for GRK5 and 1.27 (0.74-2.19) for BAG3.

CONCLUSION

By genotyping a large takotsubo cohort, we demonstrate a lack of association between candidate SNPs in the ADRB1, GRK5 and BAG3 genes, earlier suggested to contribute to TCM. Our result indicates a need to expand the search for new genetic candidates contributing to TCM.

Contribution of haplotypes across the fibrinogen gene cluster to variation in risk of myocardial infarction

Fibrinogen has consistently been recognized as an independent predictor of myocardial infarction (MI). Multiple mechanisms link fibrinogen to MI; therefore disentangling the factors underlying variation in plasma fibrinogen concentration is essential. Candidate regions in the fibrinogen gamma (FGG), alpha (FGA) and beta (FGB) genes were screened for single nucleotide polymorphisms (SNPs). Several novel SNPs were detected in the FGG and FGA genes in addition to the previously known SNPs in the fibrinogen genes. Tight linkage disequilibrium extending over various physical distances was observed between most SNPs. Consequently, eight SNPs were chosen and determined in 377 postinfarction patients and 387 healthy individuals. None of the SNPs were associated with plasma fibrinogen concentration or MI. Haplotype analyses revealed a consistent pattern of hap-lotypes associated with variation in risk of MI. Of the four haplo-types inferred using the FGA –58G> A and FGG 1299+79T> C SNPs, the most frequent haplotype, FGG-FGA*1 (prevalence 46.6%), was associated with increased risk of MI (OR 1.51; 95%CI 1.18, 1.93), whereas the least frequent haplotype, FGGFGA*4 (11.8%), was associated with lower risk of MI (OR 0.79 95%CI 0.64, 0.98). In conclusion, fibrinogen haplotypes, but not SNPs in isolation, are associated with variation in risk of MI.

Coagulation Factor V (Arg506 → Gln) Mutation and Early Saphenous Vein Graft Occlusion after Coronary Artery Bypass Grafting

The factor V (Arg506→Gln) mutation confers an increased risk of deep vein thrombosis, whereas its role in saphenous vein graft closure after coronary artery bypass grafting (CABG) remains unclear. This study examined the anticoagulant response to activated protein C (APC ratio) in relation to the surgical trauma and the significance of the factor V Leiden mutation in determining postoperative thrombin generation and fibrin formation and the risk of early vein graft occlusion. A total of 108 men undergoing elective CABG for exertional angina pectoris (mean age 61.1 ± 8.7 years) were examined. The patency of saphenous vein grafts was studied at routine reangiography three months after CABG.

Of 100 patients who underwent reangiography, 23 had one or more occluded vein grafts at reangiography. Heterozygosity for the factor V (Arg506→Gln) mutation tended to be associated with early saphenous vein graft occlusion (5/11 carriers vs. 18/89 non-carriers with graft occlusion, व2 = 3.52, p = 0.06), whereas pre- and postoperative APC ratios did not. Pre- and postoperative determinations of prothrombin fragment 1+2, thrombin-antithrombin complexes and soluble fibrin levels did not differ between patients with and without the mutation.

Early saphenous vein graft occlusion after CABG could tentatively be added to deep vein thrombosis as a vascular complication that can be attributed to the factor V (Arg506→Gln) mutation.

Effect of Interleukin-6 promoter polymorphisms in survivors of myocardial infarction and matched controls in the North and South of Europe

Elevated plasma IL-6 levels have been implicated in the pathogenesis of coronary heart disease. We have investigated the association of two polymorphisms in the promoter of IL-6 (-572G>C and -174G>C) with levels of inflammatory markers and risk of myocardial infarction (MI) in a European study of MI survivors and age-matched controls from two high-risk centres in the North of Europe, and two low risk centres in the South. IL-6 and CRP levels were similar in controls in both regions, but were higher in cases. For the -174G>C polymorphism the rare -174C allele showed a regional difference in allele frequency, being more common in the North European group (0.43 vs 0.28; p < 0.0005), where -174C allele carriers showed an apparent reduced risk of MI compared to -174GG homozygotes (OR 0.53, 95%CI 0.32, 0.86). No such effect was observed in the South or with the -572G>C in either group. Neither genotype was associated with a significant effect on plasma IL-6 levels in either cases or controls. Furthermore, no regional difference was observed in the frequency of the -572G>C SNP, suggesting that these polymorphisms are unlikely to be contributing to the observed increased risk of cardiovascular disease in Northern Europe.

Epidemiology, pathogenesis, and management of takotsubo syndrome

Takotsubo syndrome is a recently recognized acute cardiac disease entity with a clinical presentation resembling that of an acute coronary syndrome. The typical takotsubo syndrome patient has a unique circumferential left (bi-) ventricular contraction abnormality profile that extends beyond a coronary artery supply territory and appears to follow the anatomical cardiac sympathetic innervation. The syndrome predominantly affects postmenopausal women and is often preceded by emotional or physical stress. Patients with predisposing factors such as malignancy and other chronic comorbidities are more prone to suffer from takotsubo syndrome. The pathogenesis of takotsubo syndrome is elusive. Several pathophysiological mechanisms involving myocardial ischemia (multivessel coronary artery spasm, microvascular dysfunction, aborted myocardial infarction), left ventricular outlet tract obstruction, blood-borne catecholamine myocardial toxicity, epinephrine-induced switch in signal trafficking, and autonomic nervous system dysfunction have been proposed. The syndrome is usually reversible; nevertheless, during the acute stage, a substantial number of patients develop severe complications such as arrhythmias, heart failure including pulmonary edema and cardiogenic shock, thromboembolism, cardiac arrest, and rupture. Treatment of precipitating factors, predisposing diseases, and complications is fundamental during the acute stage of the disease. The epidemiology, pathogenesis, and management of takotsubo syndrome are reviewed in this paper.

Effect of Myocardial Infarction With Nonobstructive Coronary Arteries on Physical Capacity and Quality-of-Life

Patients with myocardial infarction with nonobstructive coronary arteries (MINOCA), including Takotsubo syndrome (TS), are considered to have a better survival compared with those with coronary heart disease (CHD). Studies of patients with MINOCA measuring physical and mental function including matched control groups are lacking. The aim of this study was to determine the physical capacity and quality of life in patients with MINOCA. One-hundred patients with MINOCA along with TS (25%) were investigated from 2007 to 2011. A bicycle exercise stress test was performed 6 weeks after hospitalization and QoL was investigated by the Short Form Survey 36 at 3 months' follow-up. Both a healthy and a CHD group that were age and gender matched were used as controls. The MINOCA group had a lower physical capacity (139 ± 42 W) compared with the healthy control group (167 ± 53 W, p <0.001) but better than the CHD control group (124 ± 39 W, p = 0.023). Patients with MINOCA had lower physical and mental component summary scores compared with the healthy controls (p <0.001) and lower mental component summary (p = 0.012), mental health (p = 0.016), and vitality (p = 0.008) scores compared with the CHD controls. In conclusion, the findings of this first study on exercise capacity and QoL in patients with MINOCA showed both physical and mental distress from 6 weeks to 3 months after the acute event similar to CHD controls and in some perspectives even lower scores especially in the mental component of QoL.

The value of a new cardiac magnetic resonance imaging protocol in Myocardial Infarction with Non-obstructive Coronary Arteries (MINOCA) - a case-control study using historical controls from a previous study with similar inclusion criteria

Background

Myocardial Infarction with Non-Obstructive Coronary Arteries (MINOCA) is common with a prevalence of 6% of all patients fulfilling the diagnosis of myocardial infarction. MINOCA should be considered a working diagnosis. Cardiac Magnetic Resonance (CMR) imaging has recently been suggested to be of great value to determine the cause behind MINOCA. The objectives of this paper are to describe the rationale behind the second Stockholm Myocardial Infarction with Normal Coronaries (SMINC-2) study and to discuss the protocol for investigation of MINOCA patients in the light of the recently published position paper from the European Society of Cardiology.

Methods

The SMINC-2 study is an open non-randomised study using historical controls for comparison. The primary aim is to prove that MINOCA patients investigated with the latest CMR imaging technique can achieve a diagnosis in 70% of all cases entirely by imaging. By including 150 patients we will have >80% chance to prove that the diagnostic accuracy can be improved by 20 absolute % with a p-value of less than 0.05 when compared with CMR imaging in the SMINC-1 study. Furthermore, in addition to invasive coronary angiography, coronary arteries are evaluated by computed tomography angiography to investigate coronary causes and questionnaires are used to describe Quality-of-Life (QoL). By January 1st 2017, 75 patients have been included.

Discussion

Whether CMR imaging can provide a diagnosis to an adequate proportion of MINOCA patients is unknown. Well-defined inclusion and exclusion criteria will be used to compare a MINOCA cohort from the population with an appropriate control group. Positive results are likely to influence future guidelines of the management of MINOCA. Furthermore, the study will give mechanistic insights into MINOCA in particular in patients with “true” myocardial infarction and describe QoL in this vulnerable group of patients.

Trial registration

Clinical Trials NCT02318498.

Outcome after percutaneous coronary intervention for different indications: long-term results from the Swedish Coronary Angiography and Angioplasty Registry (SCAAR)

AIMS

The aim of this study was to evaluate clinical outcome for different indications for PCI in an unselected, nationwide PCI population at short- and long-term follow-up.

METHODS AND RESULTS

We evaluated clinical outcome up to six years after PCI in all patients undergoing a PCI procedure for different indications in Sweden between 2006 and 2010. A total of 70,479 patients were treated for stable coronary artery disease (CAD) (21.0%), unstable angina (11.0%), non-ST-elevation myocardial infarction (NSTEMI) (36.6%) and ST-elevation myocardial infarction (STEMI) (31.4%). Mortality was higher in STEMI patients at one year after PCI (9.6%) compared to NSTEMI (4.7%), unstable angina (2.2%) and stable CAD (2.0%). At one year after PCI until the end of follow-up, the adjusted mortality risk (one to six years after PCI) and the risk of myocardial infarction were comparable between NSTEMI and STEMI patients and lower in patients with unstable angina and stable CAD. The adjusted risk of stent thrombosis and heart failure was highest in STEMI patients.

CONCLUSIONS

The risk of short-term mortality, heart failure and stent thrombosis is highest for STEMI patients after PCI. Therapies to reduce stent thrombosis and heart failure appear to be most important in decreasing mortality in patients with STEMI or NSTEMI undergoing PCI.

Plasma biomarker levels and non-obstructive coronary artery disease determined by coronary computed tomography angiography

PURPOSE

Coronary computed tomography angiography (CTA) and several circulating biomarkers have prognostic value regarding cardiovascular disease (CVD) events, but their association is incompletely studied. We aimed to investigate whether markers of lipid metabolism, inflammation and kidney function could predict non-obstructive coronary artery disease (CAD) determined by coronary CTA, in a low-to-intermediate-risk group.

METHODS

Coronary CTA and laboratory testing were performed for 115 subjects (45-70 years), with low prevalence of CVD risk factors, predominantly low-to-intermediate Framingham risk and normal or mildly reduced kidney function.

RESULTS

Forty-nine (43%) had no CAD at coronary CTA, and 66 (57%) had CAD in ≥1 segment (stenosis < 50%). Adiponectin was inversely associated with CAD, and lipoprotein(a) and cystatin C were associated with CAD at coronary CTA. In multivariable logistic regression, cystatin C remained an independent predictor of CAD (OR: 2·50, 95% CI: 1·12-5·59). Cystatin C also correlated to the number of diseased segments (r_s  = 0·25, P<0·01).

CONCLUSION

Higher plasma levels of cystatin C were associated with non-obstructive CAD at coronary CTA in subjects with low-to-intermediate CVD risk and normal to mildly reduced kidney function.

Ticagrelor pharmacokinetics and pharmacodynamics in patients with NSTEMI after a 180-mg loading dose

The pharmacokinetics after a 180-mg loading dose (LD) of ticagrelor has not been thoroughly investigated in NSTEMI patients. We aimed to compare the ticagrelor uptake and on-treatment platelet reactivity between non-ST-segment elevation myocardial infarction (NSTEMI) patients and a control group of patients with stable coronary artery disease (SCAD) undergoing elective percutaneous coronary intervention. We performed an observational, prospective, single-center study including 40 NSTEMI patients and 20 SCAD controls. Key exclusion criteria included ongoing opioid treatment. Both groups received a 180-mg ticagrelor LD, and blood samples were taken pre-dose and 1, 2, 3, 4, 5, and 6 hours post-LD. Plasma concentrations of ticagrelor and its active metabolite AR-C124910XX were determined by validated methods. Platelet aggregation was tested using ADP-induced multiple electrode aggregometry. The primary endpoint was the time to maximal ticagrelor concentration (T_max). Clinical trial registration identifier number: NCT02292277. None of the pharmacokinetic variables differed significantly between the groups, including the T_max of ticagrelor (2.0h [1.0-3.0] versus 2.0h [2.0-3.0], p = 0.393) and the active metabolite AR-C124910XX (3.0 [2.0-4.0] versus 3.0 [2.5-4.0], p = 0.289). High on-treatment platelet reactivity (HPR) was defined as > 46 aggregation units and was at one hour seen in 15% of the NSTEMI patients versus 10% of the controls (p = 1.0). At two hours post the 180-mg ticagrelor LD, 3% of the NSTEMI patients had HPR compared with none of the controls (p = 1.0). In conclusion, the uptake of ticagrelor was not significantly slower in NSTEMI patients not receiving opioids compared with the SCAD controls, leading to adequate onset of platelet inhibition in both groups.