Biomarkers associated with vulnerable plaques

Background

Cardiovascular heart disease is the leading cause of mortality worldwide, with the rupture or thrombosis of an atherosclerotic plaque being the main reason behind an acute coronary syndrome. It has already been established that the morphology of atherosclerotic plaques determine their stability. A lipid rich lesion with a thin fibrous cap is more prone to rupture compared to solid fibrous lesions. In the PROSPECTII study we used Near infrared spectroscopy (NIRS) and Intravascular ultrasound (IVUS) to identify atherosclerotic plaques in the coronary arteries; NIRS-derived lipid core burden index (LCBI) and IVUS-derived plaque burden (PB) identified plaques that caused adverse cardiovascular events.

Purpose

Our aim is to find biomarkers associated with LCBI or PB, to understand the development of vulnerable plaques.

Methods

902 patients were enrolled in this study after successful percutaneous coronary intervention (PCI). A combined NIRS-IVUS catheter was then used to analyze approximately 200m of coronary arteries. Blood samples for biomarker analysis were taken before the PCI procedure and plasma levels of 182 proteins associated with cardiovascular disease were assessed using a novel method for measuring proximity extension assay. Adjusted linear regression models were calculated between the biomarkers and the outcomes of interest, followed by a false discovery rate (FDR) correction.

Results

We found 24 proteins associated with plaque burden and 28 proteins associated with LCBI after using a cut off of two tailed P value <0.05. An overlap of 8 biomarkers could be seen between the two groups. After adjusting the P values with FDR, Angiopoeitin like 3 (ANGPTL3) retained its association to LCBI, and Interleukin 18 receptor 1 (IL18R1) and colony stimulating factor 1 (CSF-1) to plaque burden.

Conclusion

We were able to identify different biomarker patterns associated with plaque burden compared to lipid rich vulnerable plaques. ANGPTL3 was shown to only have an association with lipid rich plaques and not with solid fibrous lesions which further supports its role in vulnerable plaques.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Abbott Vascular, Infraredx, and The Medicines Company

Temporal changes of biomarkers in myocardial infarction patients with non-obstructive compared to obstructive coronary arteries

Background

About 5–10% of all myocardial infarction (MI) patients have non-obstructive coronary arteries (MINOCA). The pathobiology of MINOCA is largely unknown compared to myocardial infarction with obstructive coronaries (MI-CAD).

Purpose

To investigate whether baseline concentrations and temporal changes of circulating biomarkers may offer insights into the activation of pathophysiological pathways in MINOCA compared to MI-CAD.

Methods

From the PLATelet inhibition and patient Outcomes (PLATO) trial, we retrospectively identified 114 patients with MINOCA (adjudicated MI, coronary stenoses <50% and excluding patients with previous coronary revascularization) and 2750 patients with MI-CAD (adjucated MI and stenoses ≥50%) with available biomarker data. Concentrations of high sensitivity cardiac troponin T (hs-cTnT), C-reactive protein (CRP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) were centrally measured by immunoassays in plasma samples obtained at randomization/baseline (median 15 hours from index event) and after one month. Differences in biomarker concentrations and their changes were evaluated by Wilcoxon-Mann-Whitney tests and data at one month were also analysed with adjusted linear regression models.

Results

In MINOCA patients, median concentrations decreased during one month from 238 to 9 ng/L for hs-cTnT, from 3.5 to 1.6 mg/L for CRP and from 507 to 228 pmol/L for NT-proBNP (Figure 1 and 2). In MI-CAD patients, median concentrations decreased from 198 to 13 ng/L for hs-cTnT, from 3.2 to 2.3 mg/L for CRP and increased from 372 to 566 pmol/L for NT-proBNP. Compared to MI-CAD, the baseline concentrations were higher in MINOCA for NT-proBNP (p=0.011), but similar for hs-cTnT (p=0.555) and CRP (p=0.834). However, patients with MINOCA had statistically larger reductions of concentrations from baseline to one month for hs-cTnT (p=0.002), CRP (p=0.005) and NT-proBNP (p<0.001) as compared to patients with MI-CAD. At one month, concentrations were lower in MINOCA than MI-CAD patients for all three biomarkers, which remained significant after adjustment for the baseline biomarker concentration, clinical characteristics and medications (p<0.001).

Conclusions

In MINOCA compared to MI-CAD patients, higher concentrations of NT-proBNP and similar concentrations of hs-cTnT and CRP at baseline indicate a higher degree of acute myocardial dysfunction but similar degree of acute myocardial injury and inflammation. Furthermore, concentrations of these biomarkers were lower at one month in MINOCA, suggesting other or less remaining underlying disease processes after MI in MINOCA than MI-CAD.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): The present study was supported by Swedish Foundation for Strategic Research/Swedish Association of Local Authorities and Regions. The PLATO study and the biomarker analyses were sponsored by AstraZeneca.

Poor long-term prognosis in patients admitted with strong suspicion of acute myocardial infarction but discharged with another diagnosis

BACKGROUND

Characteristics and prognosis of patients admitted with strong suspicion of myocardial infarction (MI) but discharged without an MI diagnosis are not well-described.

OBJECTIVES

To compare background characteristics and cardiovascular outcomes in patients discharged with or without MI diagnosis.

METHODS

The DETermination of the role of Oxygen in suspected Acute Myocardial Infarction (DETO2X-AMI) trial compared 6629 patients with strong suspicion of MI randomized to oxygen or ambient air. The main composite end-point of this subgroup analysis was the incidence of all-cause death, rehospitalization with MI, heart failure (HF) or stroke during a follow-up of 2.1 years (median; range: 1-3.7 years) irrespective of randomized treatment.

RESULTS

1619 (24%) received a non-MI discharge diagnosis, and 5010 patients (76%) were diagnosed with MI. Groups were similar in age, but non-MI patients were more commonly female and had more comorbidities. At thirty days, the incidence of the composite end-point was 2.8% (45 of 1619) in non-MI patients, compared to 5.0% (250 of 5010) in MI patients with lower incidences in all individual end-points. However, for the long-term follow-up, the incidence of the composite end-point increased in the non-MI patients to 17.7% (286 of 1619) as compared to 16.0% (804 of 5010) in MI patients, mainly driven by a higher incidence of all-cause death, stroke and HF.

CONCLUSIONS

Patients admitted with a strong suspicion of MI but discharged with another diagnosis had more favourable outcomes in the short-term perspective, but from one year onwards, cardiovascular outcomes and death deteriorated to a worse long-term prognosis.

2209Oxygen therapy in suspected acute myocardial infarction and concurrent chronic obstructive pulmonary disease: a prespecified subgroup analysis from the DETO2X-AMI trial

Background

The DETermination of the role of Oxygen in suspected Acute Myocardial Infarction (DETO2X-AMI) trial did not find any benefit of oxygen therapy compared to ambient air in normoxemic patients with suspected acute myocardial infarction (AMI). Patients with chronic obstructive pulmonary disease (COPD) may both benefit and be harmed by supplemental oxygen. Thus, we evaluated the effect of routine oxygen therapy compared to ambient air in normoxemic COPD patients with suspected AMI.

Methods and results

A total of 6629 patients with suspected AMI were randomized in the DETO2X-AMI trial to oxygen or ambient air. In the oxygen group (n=3311) and the ambient air group (n=3318), 155 and 141 patients, respectively, had COPD (prevalence of 4.5%). Patients with COPD were older, had more comorbid conditions and experienced a two-fold higher risk of death at one year (COPD: 32/296 [10.8%] vs. non-COPD 302/6333 [4.8%]). Oxygen therapy compared to ambient air was not associated with improved outcomes at 365 days (COPD: all-cause mortality HR 0.99 [95% CI 0.50–1.99, interaction-p=0.96]; cardiovascular death HR 0.80 [0.32–2.04, interaction-p=0.59]; rehospitalization with AMI or death HR 1.27 [0.71–2.28, interaction-p=0.46]; hospitalization for heart failure or death HR 1.08 [0.61–1.91, interaction-p=0.77]); there were no significant treatment-by-COPD interactions.

Outcome

Conclusions

Although COPD patients had twice the mortality rate compared to non-COPD patients, this prespecified subgroup analysis from the DETO2X-AMI trial on oxygen therapy versus ambient air in normoxemic COPD patients with suspected AMI revealed no evidence for benefit of routine oxygen therapy consistent with the main trial's findings.

88Oxygen therapy in myocardial infarction patients with or without diabetes mellitus - A predefined subgroup analysis from the DETO2X-AMI trial

Background

In diabetes, there is an interaction between hyperglycaemia and cellular hypoxia, which may induce oxidative stress. Oxygen therapy in patients with diabetes and myocardial infarction (MI) has not been studied.

Purpose

Our aim was to determine the effects of supplemental oxygen in MI patients with or without diabetes.

Methods

The DETermination of the role of Oxygen in suspected Acute Myocardial Infarction (DETO2X-AMI) trial randomised 6629 patients with suspected myocardial infarction (MI) to receive oxygen at 6 L/min for 6–12 hours or ambient air. In this prespecified analysis involving 5010 patients with confirmed MI, 934 had known diabetes (19%). The main composite endpoint was the effect of supplemental oxygen on all-cause death, rehospitalisation with MI, or heart failure at one year in patients with diabetes. Key secondary endpoint was the comparison between patients with or without diabetes.

Results

In patients with diabetes, the main composite endpoint occurred in 16.2% (72 of 445) of patients allocated to oxygen compared to 16.6% (81 of 489) allocated to ambient air (hazard ratio [HR] 0.93; 95% confidence interval [CI], 0.67–1.27, P=0.81) at one year (figure). There was no statistically significant difference for the individual components of the main composite endpoint, or the rate of cardiovascular death up to one year. In comparison, corresponding endpoints in patients without diabetes were similar between the treatment groups.

However, when comparing patients according to diabetes status, event rates were significantly higher in the diabetic population (main composite endpoint: HR 1.60; 95% CI, 1.32–1.93, P<0.01).

Kaplan-Meier curves for main endpoint

Conclusions

Oxygen therapy in normoxemic MI patients did not significantly affect 1-year all-cause death, cardiovascular death, rehospitalisation with MI or heart failure, irrespective of underlying diabetes. Noteworthy, despite that the incidence of cardiovascular outcomes has declined substantially in patients with diabetes over the last decades, we still observed markedly increased event rates in patients with diabetes.

Acknowledgement/Funding

Swedish Heart-Lung Foundation; Swedish Research Council; Stockholm County Council

Collaborative meta-analysis of individual participant data from observational studies of Lp-PLA2 and cardiovascular diseases

BACKGROUND

A large number of observational epidemiological studies have reported generally positive associations between circulating mass and activity levels of lipoprotein-associated phospholipase A2 (Lp-PLA2) and the risk of cardiovascular diseases. Few studies have been large enough to provide reliable estimates in different circumstances, such as in different subgroups (e.g., by age group, sex, or smoking status) or at different Lp-PLA2 levels. Moreover, most published studies have related disease risk only to baseline values of Lp-PLA2 markers (which can lead to substantial underestimation of any risk relationships because of within-person variability over time) and have used different approaches to adjustment for possible confounding factors.

OBJECTIVES

By combination of data from individual participants from all relevant observational studies in a systematic 'meta-analysis', with correction for regression dilution (using available data on serial measurements of Lp-PLA2), the Lp-PLA2 Studies Collaboration will aim to characterize more precisely than has previously been possible the strength and shape of the age and sex-specific associations of plasma Lp-PLA2 with coronary heart disease (and, where data are sufficient, with other vascular diseases, such as ischaemic stroke). It will also help to determine to what extent such associations are independent of possible confounding factors and to explore potential sources of heterogeneity among studies, such as those related to assay methods and study design. It is anticipated that the present collaboration will serve as a framework to investigate related questions on Lp-PLA2 and cardiovascular outcomes.

METHODS

A central database is being established containing data on circulating Lp-PLA2 values, sex and other potential confounding factors, age at baseline Lp-PLA2 measurement, age at event or at last follow-up, major vascular morbidity and cause-specific mortality. Information about any repeat measurements of Lp-PLA2 and potential confounding factors has been sought to allow adjustment for possible confounding and correction for regression dilution. The analyses will involve age-specific regression models. Synthesis of the available observational studies of Lp-PLA2 will yield information on a total of about 15 000 cardiovascular disease endpoints.

Assessment of a simple colorimetric procedure to determine smoking status in diabetic subjects

The performance of a colorimetric assay for nicotine metabolites to validate self-reported smoking classification (nonsmoker, ex-smoker, and smoker) was assessed in a group of diabetic patients (n = 201). Comparison of the results with those of cotinine immunoassay (ELISA), by comparing respective areas under receiver operating characteristic curves, established the superiority of the cotinine immunoassay method. Adjusting the urinary concentrations of nicotine metabolites for creatinine excretion significantly lowered test performance. The sensitivity and specificity for the assay of nicotine metabolites to discriminate smoking classification within the diabetic patients at a threshold of &gt; or = 28 mumol/L "cotinine carboxylic acid equivalents" were 68.4% and 98.6%, respectively; the corresponding sensitivity and specificity for urinary cotinine at a cutoff of &gt; or = 0.5 mumol/L were 94.7% and 100%. The low sensitivity of the colorimetric urinary nicotine metabolites assay precludes its application as an objective assessment of smoking status in our patient population.

Enzymatic quantification of 1,5-anhydro-D-glucitol: evaluation and clinical application

We investigated an enzymatic colorimetric procedure for quantification of plasma 1,5-anhydro-D-glucitol (AG) with respect to its reproducibility and application for evaluation of diabetes mellitus. Assay specificity is critically dependent on the two-layer ion-exchange column chromatography procedure to remove glucose from the sample. For female nondiabetic subjects (n = 110, ages 22-36 years) the median plasma AG concentration was 143 mumol/L (range 70-209 mumol/L); there was no relation to body mass index (BMI), fasting plasma glucose, or insulin, but an inverse association was noted for age. For a group of older subjects (n = 69, 70-85 years), no association between AG concentrations and sex, age, BMI, or various medical conditions was found. In diabetic subjects (n = 170) a significant inverse nonlinear relation existed between plasma AG and glycohemoglobin (GHb) such that at GHb &gt; 8.5%, AG concentrations were typically &lt; 50 mumol/L. The findings confirm that plasma AG, in the presence of normal renal function, is a reliable marker for hyperglycemia.

Assessment of a simple colorimetric procedure to determine smoking status in diabetic subjects

The performance of a colorimetric assay for nicotine metabolites to validate self-reported smoking classification (nonsmoker, ex-smoker, and smoker) was assessed in a group of diabetic patients (n = 201). Comparison of the results with those of cotinine immunoassay (ELISA), by comparing respective areas under receiver operating characteristic curves, established the superiority of the cotinine immunoassay method. Adjusting the urinary concentrations of nicotine metabolites for creatinine excretion significantly lowered test performance. The sensitivity and specificity for the assay of nicotine metabolites to discriminate smoking classification within the diabetic patients at a threshold of > or = 28 mumol/L "cotinine carboxylic acid equivalents" were 68.4% and 98.6%, respectively; the corresponding sensitivity and specificity for urinary cotinine at a cutoff of > or = 0.5 mumol/L were 94.7% and 100%. The low sensitivity of the colorimetric urinary nicotine metabolites assay precludes its application as an objective assessment of smoking status in our patient population.

Enzymatic quantification of 1,5-anhydro-D-glucitol: evaluation and clinical application

We investigated an enzymatic colorimetric procedure for quantification of plasma 1,5-anhydro-D-glucitol (AG) with respect to its reproducibility and application for evaluation of diabetes mellitus. Assay specificity is critically dependent on the two-layer ion-exchange column chromatography procedure to remove glucose from the sample. For female nondiabetic subjects (n = 110, ages 22-36 years) the median plasma AG concentration was 143 mumol/L (range 70-209 mumol/L); there was no relation to body mass index (BMI), fasting plasma glucose, or insulin, but an inverse association was noted for age. For a group of older subjects (n = 69, 70-85 years), no association between AG concentrations and sex, age, BMI, or various medical conditions was found. In diabetic subjects (n = 170) a significant inverse nonlinear relation existed between plasma AG and glycohemoglobin (GHb) such that at GHb > 8.5%, AG concentrations were typically < 50 mumol/L. The findings confirm that plasma AG, in the presence of normal renal function, is a reliable marker for hyperglycemia.

Screening for microalbuminuria by use of a rapid, low-cost colorimetric assay

We evaluated the pyrogallol red-molybdate(IV) method for quantification of urinary protein as a screening procedure for microalbuminuria by determining the assay's sensitivity and specificity at different concentrations of urinary albumin as measured by a comparison laser-nephelometric immunoassay. The pyrogallol red-molybdate(IV) method has sensitivity and specificity similar to that for other semiquantitative assays, but it is less expensive and sample throughput can be high if microtiter plate techniques are used.

Screening for microalbuminuria by use of a rapid, low-cost colorimetric assay

We evaluated the pyrogallol red-molybdate(IV) method for quantification of urinary protein as a screening procedure for microalbuminuria by determining the assay's sensitivity and specificity at different concentrations of urinary albumin as measured by a comparison laser-nephelometric immunoassay. The pyrogallol red-molybdate(IV) method has sensitivity and specificity similar to that for other semiquantitative assays, but it is less expensive and sample throughput can be high if microtiter plate techniques are used.

Capillary gas chromatographic measurement of neutral urinary steroids: evaluation and comparison with alternative methodology

The major neutral urinary steroids have been quantitated by capillary gas chromatography and the reproducibility and accuracy of the method have been fully evaluated. Typical intra- and inter-assay coefficients of variation for individual steroids ranged from 4.9 to 10.1% and from 15.6 to 21.5%, respectively. Comparison of steroid values with alternate and commonly employed procedures for measuring urinary 17-oxosteroids, total 17-oxogenic steroids, and cortisol and plasma dehydroepiandrosterone-sulphate yielded correlation coefficients between 0.71 and 0.79. A definite relationship between serum cortisol and urinary trihydroxy-pregnanedione was also shown. Urinary androstenedione metabolites, however, could not be significantly (P greater than 0.05) correlated with the normalised androgen ratio in plasma.