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

P1966Impact of coronary artery calcification on long-term outcomes after implantation of first and second-generation drug-eluting stents: a patient-level analysis of 18 randomized trials

Background

Available data on the long-term impact of coronary artery calcification (CAC) after percutaneous coronary intervention (PCI) with drug-eluting stents (DES) are limited.

Purpose

We evaluated the long-term impact of CAC on outcomes after PCI and the respective performance of first- and second-generation DES.

Methods

We pooled patient-level data from 18 randomized trials evaluating DES categorized according to the presence of angiographic core lab-confirmed moderate or severe CAC in any target lesion. Outcome measures of interest were the patient-oriented composite endpoint (POCE; death, myocardial infarction [MI], or any revascularization), the device-oriented composite endpoint of target lesion failure (TLF; cardiac death, target vessel MI or ischemia-driven target lesion revascularization), and definite or probable stent thrombosis (ST). Multivariable Cox proportional regression with study as a random effect was used to assess 5-year outcomes.

Results

A total of 19,833 patients were included. Moderate or severe CAC was present in 6211 (31.3%) patients and associated with increased 5-year risk of the POCE (adjHR 1.12, 95% CI 1.05–1.20, p<0.001), TLF (adjHR 1.21, 95% CI 1.09–1.35, p<0.001), and a trend for greater ST (adjHR 1.24, 95% CI 0.99–1.54, p=0.06). In patients with CAC, second-generation DES were associated with a reduction in the 5-year risk of TLF and ST, and a trend for reduced POCE compared with first-generation DES (Table).

Conclusion

In this large-scale study, target lesion moderate or severe CAC was associated with adverse patient- and device-related outcomes at 5 years, risks that were reduced but not eliminated with second-generation DES.

Acknowledgement/Funding

This investigator-sponsored study was funded by Abbott Vascular.

Regulation of myocardial contractility: Insights from transgenic mice

Myocardial contraction occurs when calcium (Ca(2+)) is released from the sarcoplasmic reticulum, binding troponin C and allowing actin and myosin to cross link. Ca(2+) release and uptake is closely regulated by G protein-coupled β-adrenergic receptors through the action of the second messenger cAMP. An increase in cAMP level leads to phosphorylation of key regulatory proteins affecting intracellular Ca(2+) homeostasis. The β-adrenergic receptors themselves are regulated by a set of specific kinases, termed the G-protein-coupled receptor kinases (GRKs). The study of this complex system in vivo has recently been advanced by the development of transgenic and gene-targeted (knockout) mouse models. Combining transgenic technology with sophisticated physiological measurements of cardiac hemodynamics is an extremely powerful approach to the study of myocardial contractility and its regulation. This review focuses on several recent transgenic mouse models that have increased our understanding of the regulation of cardiac contractility.

Improvement of coronary artery endothelial dysfunction with lipid-lowering therapy: heterogeneity of segmental response and correlation with plasma-oxidized low density lipoprotein

OBJECTIVES

This study assessed coronary artery endothelial function in patients with hypercholesterolemia before and after lipid lowering, using quantitative angiography to examine the acetylcholine (Ach) response along the entire analyzable vessel.

BACKGROUND

Lipid lowering reverses endothelial dysfunction, but whether improvement occurs only in some segments and not others has not been established. Statistical correlation of improvement with specific lipid moieties remains undefined.

METHODS

Quantitative angiography was performed after Ach (10(-6), 10(-5), 10(-4) M) in 29 patients with coronary atherosclerosis before and 18 +/- 5.2 months after lipid-lowering treatment (statins, bile sequestrant resins). Standard lipid moieties and markers of oxidized low density lipoprotein (LDL) (immunoglobulin G and M autoantibody titers to malondialdehyde-LDL, E06 epitope) were measured serially.

RESULTS

Pre-treatment of the vessel diameters at control and with 10(-6)M, 10(-5) M and 10(-4) M Ach were 2.108 +/- 0.085, 2.086 +/- 0.087, 2.069 +/- 0.084 and 1.963 +/- 0.097 mm (M +/- SE), respectively, and increased at follow-up to 2.139 +/- 0.094, 2.119 +/- 0.086, 2.127 +/- 0.084 and 2.080 +/- 0.085 mm (p < 0.0001). Improvement in the most constricted and modest declination in the more dilated segments were observed. Change in the E06 and Apolipoprotein A-1 titers correlated with improved vasomotion (p = 0.027 and 0.005, respectively). The pre- and post-treatment levels of the E06 epitope, as well as the post-treatment IgM autoantibody titer to MDA-low density lipoprotein, also correlated (p < 0.028, < 0.001 and p < 0.004, respectively).

CONCLUSIONS

Drug treatment reverses endothelial dysfunction, but the effect is heterogeneous. Most coronary segments show enhancement, while others show declination of dilation, underscoring the importance of assessing the entire analyzable artery. Improvement in vasomotion correlates most significantly with markers of plasma-oxidized low-density lipoprotein.

Doxycycline prophylaxis for shigellosis

The efficacy of oral doxycycline, 100 mg/d for 14 days, in reducing the incidence of shigellosis in newcomers to an area hyperendemic for the disease was examined in a double-blind, placebo-controlled trial. Of 107 entrants, 100 completed the study; 50 received the drug and 50 received a placebo. Diarrheal disease and associated symptoms were monitored for 8 weeks. Starting on the 3rd day of the trial, an outbreak was observed, and Shigella flexneri type 2a was isolated from 6 subjects. Eight of the subjects in the treatment group had diarrhea (16%) compared with 37 in the placebo group (74%), providing a 79% protection rate. There was no significant difference in the occurrence of accompanying symptoms between the subjects suffering from diarrhea in both groups, but the duration of disease was shorter in the treatment group. Serologic study of the outbreak showed no significant difference in antibody response to S flexneri between the treatment (14 of 43) and placebo (18 of 39) groups. Doxycycline prophylaxis apparently is effective and probably does not prevent subclinical infection.

Autoimmune diseases other than lupus share common anti-DNA idiotypes

We examined the sera of 170 patients with various autoimmune diseases other than systemic lupus erythematosus (SLE) for the presence of an anti-DNA antibody idiotype termed 16/6 and known to occur with high frequency in sera of patients with SLE. The idiotype was found in 6/15 sera from patients with polymyositis (49%), 3/18 with multiple sclerosis (17%), 3/18 with primary Sjögren's syndrome (18%), 9/40 with autoimmune thyroid diseases (23%), 2/35 with myasthenia gravis (6%), and 3/42 patients with rheumatoid arthritis (7%). The idiotype was not detected among 12 patients with scleroderma or 77 normal controls. The presence of the 16/6 idiotype was associated with the presence of another anti-DNA idiotype termed 134-Id. Serum samples were also tested for activity against DNA, various synthetic polynucleotides, and cardiolipin. The serum activity against these antigens was found to be polyspecific, though overlap in reaction against the various polynucleotides was not absolute. The 16/6 idiotype is thought to be coded by a germline gene. The presence of this idiotype in various autoimmune diseases points to a pathophysiologic link between the diseases.

Detection of anti-histone activity in sera of patients with monoclonal gammopathies

Sera from 249 patients with monoclonal gammopathies (85 multiple myeloma, 92 benign monoclonal gammopathies, 53 cryoglobulinemia, 19 Waldenström's macroglobulinemia) were examined for the presence of anti-histone activity. Thirty-four sera were found positive. In 12 of these cases the serum monoclonal immunoglobulins were purified and in all, the anti-histone activity appeared to reside in the monoclonal component. None of the patients had symptomatology of lupus despite high titers of anti-histone activity. This study demonstrates an anti-histone activity of monoclonal components of patients with monoclonal gammopathies.

The detection of a common idiotype of anti-DNA antibodies in the sera of patients with monoclonal gammopathies

The sera of 265 patients with monoclonal gammopathies were examined for the presence of a dominant idiotype of the anti-DNA antibody [16/6 idiotype (Id)] and for anti-DNA activity. An enzyme-linked immunosorbent assay (ELISA) with a rabbit anti-16/6 antibody revealed 23 (8.7%) sera that contained increased concentrations of the idiotype. Seven of the patients had benign monoclonal gammopathy, three multiple myeloma, three Waldenström macroglobulinemia, five essential mixed cryoglobulinemia, and five monoclonal cryoglobulinemia. In 5 of the 23 sera, antinuclear activity was also noted. In 11 of the 16/6 Id-positive sera the anti-nucleic acid antibody reactions were found to be polyspecific, reacting with polydeoxythymidilic acid and polyinosinic acid, in addition to single-stranded DNA and double-stranded DNA. Similar results were achieved with the purified serum monoclonal components. The specificity of the idiotype analysis was demonstrated with an unrelated dominant idiotype of anti-HBsAg antibody. In none of the patients, except one (with essential mixed cryoglobulinemia), was lupus symptomatology noted.