Giovanni Cimmino

Early Metoprolol Administration Before Coronary Reperfusion Results in Increased Myocardial Salvage Analysis of Ischemic Myocardium at Risk Using Cardiac Magnetic Resonance

Background— &bgr;-Blockers improve clinical outcome when administered early after acute myocardial infarction. However, whether &bgr;-blockers actually reduce the myocardial infarction size is still in dispute. Cardiac magnetic resonance imaging can accurately depict the left ventricular (LV) ischemic myocardium at risk (T2-weighted hyperintense region) early after myocardial infarction, as well as the extent of necrosis (delayed gadolinium enhancement). The aim of this study was to determine whether early administration of metoprolol could increase myocardial salvage, measured as the difference between the extent of myocardium at risk and myocardial necrosis. Methods and Results— Twelve Yorkshire pigs underwent a 90-minute left anterior descending coronary occlusion, followed by reperfusion. They were randomized to metoprolol (7.5 mg during myocardial infarction) or placebo. Global and regional LV function, extent of myocardium at risk, and myocardial necrosis were quantified by cardiac magnetic resonance imaging studies performed 4 and 22 days after reperfusion in 10 survivors. Despite similar extent of myocardium at risk in metoprolol- and placebo-treated pigs (30.9% of LV versus 30.6%; P=NS), metoprolol resulted in 5-fold-larger salvaged myocardium (32.4% versus 6.2% of myocardium at risk; P=0.015). The LV ejection fraction significantly improved in metoprolol-treated pigs between days 4 and 22 (37.2% versus 43.0%; P=0.037), whereas it remained unchanged in pigs treated with placebo (35.1% versus 35.0%; P=NS). The extent of myocardial salvage was related directly to LV ejection fraction improvement (P=0.031) and regional LV wall motion recovery (P=0.039) at day 22. Conclusions— Early metoprolol administration during acute coronary occlusion increases myocardial salvage. The extent of myocardial salvage, measured as the difference between myocardium at risk and myocardial necrosis, was associated with regional and global LV motion improvement.

Rapid change in plaque size, composition, and molecular footprint after recombinant apolipoprotein A-I Milano (ETC-216) administration: magnetic resonance imaging study in an experimental model of atherosclerosis

OBJECTIVES This study sought to assess the effect of short-term apolipoprotein (apo) A-I(Milano) administration on plaque size and on suspected markers of plaque vulnerability. BACKGROUND Long-term lipid-lowering interventions can regress and stabilize atherosclerotic plaques. However, the majority of recurrent events occur early after the first episode. Interventions able to acutely induce plaque regression and stabilization are lacking. Regression of human coronary lesions after 5 weeks of treatment with apoA-I(Milano) administration has been shown. However, there are no data regarding its effect on plaque vulnerability. METHODS Advanced aortic lesions were induced in New Zealand White rabbits (n = 40). Plaque size was assessed by magnetic resonance imaging (MRI) at the end of atherosclerosis induction. Animals were randomized to placebo or apoA-I(Milano) phospholipids (ETC-216), 2 infusions 4 days apart. After the last dose, another MRI study was performed and aortas were processed for cellular composition and gene protein expression of markers associated with plaque instability. RESULTS Pre-treatment MRI showed similar plaque size in both groups, whereas post-treatment MRI showed 6% smaller plaques in apoA-I(Milano)-treated animals compared with placebo (p = 0.026). The apoA-I(Milano) treatment induced a 5% plaque regression (p = 0.003 vs. pre-treatment), whereas the placebo showed no significant effect. Plaque regression by apoA-I(Milano) was associated with a reduction in plaque macrophage density and a significant down-regulation in gene and protein expression of tissue factor, monocyte chemoattractant protein-1, and cyclooxygenase-2, as well as marked decrease in gelatinolytic activity. Conversely, cyclooxygenase-1 was significantly up-regulated. CONCLUSIONS Acute plaque regression observed after short-term apoA-I(Milano) administration was associated with a significant reduction in suspected makers of plaque vulnerability in an experimental model of atherosclerosis.

Patients With Acute Coronary Syndrome Show Oligoclonal T-Cell Recruitment Within Unstable Plaque Evidence for a Local, Intracoronary Immunologic Mechanism

Background— Recent studies indicate that T-cell activation may play an important role in the pathophysiology of acute coronary syndromes (ACS). However, although those studies detected T-cell expansion in peripheral blood cells, demonstration of specific T-cell expansion within the plaque of patients with ACS is lacking. The present study aims to address whether a specific, immune-driven T-lymphocyte recruitment occurs within the unstable plaque of patients with ACS. Methods and Results— We simultaneously examined the T-cell repertoire using CDR3 size analysis both in coronary plaques (obtained by directional atherectomy) and in peripheral blood of patients with either ACS (n=11) or chronic stable angina (n=10). Unstable plaques showed a 10-fold increase in T-cell content by quantitative PCR. Using spectratyping analysis, we found several specific T-cell clonotype expansions only in unstable plaque from each patient with ACS, indicating a specific, antigen-driven recruitment of T cells within unstable lesions. Conclusions— For the first time, T-cell repertoire was investigated directly into coronary plaques; using this approach, we demonstrate that coronary plaque instability in the setting of ACS is associated with immune-driven T-cell recruitment, specifically within the plaque.

Recombinant HDLMilano exerts greater anti-inflammatory and plaque stabilizing properties than HDLwild-type

OBJECTIVE The aim of this study was to compare the effects of HDL(Milano) and HDL(wild-type), on regression and stabilization of atherosclerosis. METHODS Atherosclerotic New Zealand White rabbits received 2 infusions, 4 days apart, of HDL(Milano) (75mg/kg of apoA-I(Milano)), HDL(wild-type) (75mg/kg apoA-I(wild-type)) or placebo. Pre- and post-treatment plaque volume was assessed by MRI. Markers of plaque vulnerability and inflammation were evaluated. Liver and aortic cholesterol content, aortic ABCA-1 and liver SR-BI were quantified. The effect of apoA-I Milano and wild-type proteins on MCP-1 and COX-2 expression by macrophages was evaluated in vitro. RESULTS Both forms of HDL induced aortic plaque regression (-4.1% and -2.6% vs. pre-treatment in HDL(Milano) and HDL(wild-type) respectively, p<0.001 and p=0.009). A similar reduction in cholesterol content of aorta and liver was observed with both treatments vs. placebo. The expression of aortic ABCA-1 and hepatic SR-BI was significantly higher in both treated groups vs. placebo. A significantly reduced plaque macrophage density was observed in the HDL(Milano) vs. both HDL(wild-type) and placebo groups. Plaque levels of COX-2, MCP-1, Caspase-3 antigen and MMP-2 activity were significantly reduced in the HDL(Milano) vs. both HDL(wild-type) and placebo groups. In vitro studies showed that apoA-I(Milano) protein significantly reduced expression of COX-2 and MCP-1 in oxLDL loaded macrophages vs. apoA-I(wild-type). CONCLUSIONS Despite a similar effect on acute plaque regression, the infusion of HDL(Milano) exerts superior anti-inflammatory and plaque stabilizing effects than HDL(wild-type) in the short term.

Recombinant apolipoprotein A-I Milano rapidly reverses aortic valve stenosis and decreases leaflet inflammation in an experimental rabbit model

AIMS Aortic stenosis (AS) is associated with significant morbidity and mortality. Recombinant apolipoprotein A-I Milano (rApoA-I(M)) induces atherosclerotic plaque regression. The aims of this study were to determine the effects of rApoA-I(M) on experimental aortic valve degeneration and its mechanisms of action. METHODS AND RESULTS New Zealand White rabbits (n = 20) were fed an atherogenic diet for 9 months and then randomized to either placebo or rApoA-I(M). Echocardiography was used to assess the effect of the treatments on AS. Porcine aortic valve myofibroblasts (PAVMF) treated with oxidized low-density lipoprotein served to define the effects of rApoA-I(M) on the expression of monocyte chemoattractant protein-1 (MCP-1), nuclear factor (NF)-kappaB, and alkaline phosphatase (AP). Recombinant apolipoprotein A-I Milano increased aortic valve area (AVA) by 32% (0.25 +/- 0.05 to 0.34 +/- 0.07 cm(2), P < 0.01); whereas AVA remained unchanged in the placebo group (0.24 +/- 0.05 to 0.26 +/- 0.04 cm(2), P = 0.58). Histopathological examination of aortic valves in the rApoA-I(M) animals showed significantly less leaflet thickening, inflammation, and calcification vs. the placebo group. In vitro, rApoA-I(M) significantly inhibited MCP-1, AP, and NF-kappaB and decreased intracellular cholesterol content in PAVMF. CONCLUSION Recombinant apolipoprotein A-I Milano treatment reverses AS in this experimental rabbit model. The beneficial effects seem to be mediated by enhanced cholesterol removal and by reduced inflammation and calcification.

Platelets release matrix metalloproteinase-2 in the coronary circulation of patients with acute coronary syndromes: possible role in sustained platelet activation

AIMS To investigate whether selected matrix metalloproteinases (MMPs) are released in the coronary circulation of patients with acute coronary syndrome (ACS), whether this release is related to platelet activation, and whether it contributes to sustained platelet activation. METHODS AND RESULTS Blood from the aorta (Ao) and the coronary sinus (Cs) was obtained from 21 controls (non-cardiac chest pain), 24 stable angina (SA), and 30 ACS patients, before performing percutaneous transluminal coronary angioplasty. Selected MMPs, some platelet activation- and atheroma-related markers, and the platelet activation-potentiating activity of plasma were measured. Total MMP-2, active MMP-2, and MMP-9 were released in the coronary circulation of patients with ACS, but not of those with SA or controls. Similarly, transcoronary gradients of β-thromboglobulin (β-TG) and platelet factor 4, two platelet-specific proteins, and of soluble CD40L and secretory phospholipase A₂ (sPLA₂), markers of inflammation and platelet activation, were higher in ACS patients than in the other groups. In contrast, plasma monocyte chemoattractant protein-1, a platelet-unrelated marker of atherogenesis, was not increased in the Cs compared with Ao in any of the groups. Transcoronary gradients of both β-TG and sPLA₂ correlated with those of total and active MMP-2 in ACS, but not in controls or SA. Plasma from the Cs of ACS patients potentiated platelet activation, an effect suppressed by the specific MMP-2-inhibitor, tissue inhibitor of MMP-2 (TIMP-2). CONCLUSION Matrix metalloproteinase-2 is released in the coronary circulation of ACS patients, derives in part from activated platelets, and may contribute to sustained intracoronary platelet activation.

Genesis and dynamics of atherosclerotic lesions: implications for early detection.

Atherosclerosis is a diffuse pathological process characterized by the deposition of lipid and other blood-borne material within the arterial wall of almost all vascular territories. Cholesterol accumulation plays a central role in atherogenesis. It is the result of an imbalance between cholesterol influx and efflux. The disease progresses silently with focal clinical manifestation due to plaque rupture with superimposed thrombus: atherothrombosis. It has been shown that the atherosclerotic plaque composition rather than the degree of arterial stenosis can be the determinant of rupture. This has led to the search for new imaging techniques that can provide information about plaque composition. Ultrasound measurements of carotid and aortic wall thickness are an accurate ‘noninvasive’ technique that permits correlation with clinical events. Magnetic resonance imaging can evaluate in detail the arterial anatomy of almost all vascular territories. Multidetector computed tomography recently emerged for measuring luminal stenosis, coronary calcium, and even the extent of non-calcified coronary plaque volume. Next future is the molecular imaging based on the knowledge of molecular mechanisms involved in the genesis and progression of atherosclerotic lesions and the contrast agent able to identify different molecules and/or cells in the target zone.

The cardioprotection granted by metoprolol is restricted to its administration prior to coronary reperfusion

BACKGROUND Myocardial infarct size is a strong predictor of cardiovascular events. Intravenous metoprolol before coronary reperfusion has been shown to reduce infarct size; however, it is unknown whether oral metoprolol initiated early after reperfusion, as clinical guidelines recommend, is similarly cardioprotective. We compared the extent of myocardial salvage associated with intravenous pre-reperfusion-metoprolol administration in comparison with oral post-reperfusion-metoprolol or placebo. We also studied the effect on suspected markers of reperfusion injury. METHODS Thirty Yorkshire-pigs underwent a reperfused myocardial infarction, being randomized to pre-reperfusion-metoprolol, post-reperfusion-metoprolol or placebo. Cardiac magnetic resonance imaging was performed in eighteen pigs at day 3 for the quantification of salvaged myocardium. The amounts of at-risk and infarcted myocardium were quantified using T2-weighted and post-contrast delayed enhancement imaging, respectively. Twelve animals were sacrificed after 24h for reperfusion injury analysis. RESULTS The pre-reperfusion-metoprolol group had significantly larger salvaged myocardium than the post-reperfusion-metoprolol or the placebo groups (31 ± 4%, 13 ± 6%, and 7 ± 3% of myocardium at-risk respectively). Post-mortem analyses suggest lesser myocardial reperfusion injury in the pre-reperfusion-metoprolol in comparison with the other 2 groups (lower neutrophil infiltration, decreased myocardial apoptosis, and higher activation of the salvage-kinase phospho-Akt). Salvaged myocardium and reperfusion injury pair wise comparisons proved there were significant differences between the pre-reperfusion-metoprolol and the other 2 groups, but not among the latter two. CONCLUSIONS The intravenous administration of metoprolol before coronary reperfusion results in larger myocardial salvage than its oral administration initiated early after reperfusion. If confirmed in the clinical setting, the timing and route of β-blocker initiation could be revisited.

Up‐regulation of reverse cholesterol transport key players and rescue from global inflammation by ApoA‐IMilano

Recombinant‐ApoA‐IM (rApoA‐IM) administration has been shown to regress and stabilize atherosclerotic plaques. However, the mechanisms responsible for these beneficial effects are not fully understood. The aims of the present study were to define whether the benefits of rApoA‐IM treatment were mediated via an enhanced reverse cholesterol transport (RCT) and/or anti‐inflammation‐related mechanisms. Advanced aortic lesions were induced in New Zealand White rabbits (n= 16). Animals were randomized to placebo or rApoA‐IM (rApoA‐IM/phospholipids; ETC‐216), two infusions 4 days apart. Four days after last dose, aortas and livers were processed for cholesterol content, expression of RCT‐related receptors (ATP‐binding cassette A‐1 [ABCA‐1] and scavenger receptor BI [SR‐BI]), and inflammation‐related markers (inducible nitric oxide synthase [iNOS] and capase‐3). Oxidative stress was assessed in the vessel wall and in plasma. rApoA‐IM administration resulted in a significant reduction in the hepatic and aortic cholesterol content without differences in plasma levels. This effect was associated with an up‐regulation of vessel wall ABCA‐1, as well as a hepatic and arterial‐wall SR‐BI up‐regulation. Systemic and atherosclerotic‐plaque inflammation markers were significantly reduced by the rApoA‐IM administration, as demonstrated by a reduction in circulating oxidative stress markers and prostaglandin F1‐α levels, and the down‐regulation of the iNOS and caspase 3 in the aortic lesions. rApoA‐IM up‐regulated the ABCA‐1 and SR‐BI levels to a greater extent than the wild‐type form of apoA‐I in in vitro studies done with lipid‐rich macrophages. Our data suggest that rApoA‐IM administration enhances RCT and induces a ‘rescue’ from the global inflammatory status associated with atherosclerotic disease. The Milano form of apoA‐I seems to be more efficient in RCT than the apoA‐I wild‐type.

Assessment of plasma tissue factor activity in patients presenting with coronary artery disease: limitations of a commercial assay

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