Real-time catheter molecular sensing of inflammation in proteolytically active atherosclerosis.

BACKGROUND: To enable intravascular detection of inflammation in atherosclerosis, we developed a near-infrared fluorescence (NIRF) catheter-based strategy to sense cysteine protease activity during vascular catheterization. METHODS AND RESULTS: The NIRF catheter design was based on a clinical coronary artery guidewire. In phantom studies of NIRF plaques, blood produced only a mild (<30%) attenuation of the fluorescence signal compared with saline, affirming the favorable optical properties of the NIR window. Catheter evaluation in vivo used atherosclerotic rabbits (n=11). Rabbits received an injection of a cysteine protease-activatable NIRF imaging agent (Prosense750; excitation/emission, 750/770 nm) or saline. Catheter pullbacks through the blood-filled iliac artery detected NIRF signals 24 hours after injection of the probe. In the protease agent group, the in vivo peak plaque target-to- BACKGROUND: <0.05). Ex vivo fluorescence reflectance imaging corroborated these results (target-to- BACKGROUND: <0.01). In the protease group only, saline flush-modulated NIRF signal profiles further distinguished atheromata from normal segments in vivo (P<0.01). Good correlation between the in vivo and ex vivo plaque target-to- BACKGROUND: =0.82, P<0.01). Histopathological analyses demonstrated strong NIRF signal in plaques only from the protease agent group. NIRF signals colocalized with immunoreactive macrophages and the cysteine protease cathepsin B. CONCLUSIONS: An intravascular fluorescence catheter can detect cysteine protease activity in vessels the size of human coronary arteries in real time with an activatable NIRF agent. This strategy could aid in the detection of inflammation and high-risk plaques in small arteries.

Delayed arterial healing and increased late stent thrombosis at culprit sites after drug-eluting stent placement for acute myocardial infarction patients: an autopsy study.

BACKGROUND: The long-term safety of drug-eluting stents (DES) for acute myocardial infarction (AMI) remains uncertain. Using autopsy data, we evaluated the pathological responses of the stented segment in patients treated with DES for AMI and compared with patients with stable angina. METHODS AND RESULTS: From the CVPath Registry of 138 DES autopsies, we identified 25 patients who presented with AMI and had an underlying necrotic core with a ruptured fibrous cap. Twenty-six patients who had stable angina with thick-cap fibroatheroma treated by DES were selected as controls. Histomorphometric analysis was performed in patients with >30-day stent duration. We compared the response to stenting at the culprit site in these 2 groups and to nonculprit sites within each stent. Late stent thrombosis was significantly less frequent in stable (11%) than in AMI (41%; P=0.04) patients. Although neointimal thickness in the AMI culprit site was significantly less (median, 0.04 mm; interquartile range [IQR], 0.02 to 0.09 mm), the prevalence of uncovered struts (49%; IQR, 16% to 96%), fibrin deposition (63+/-28%), and inflammation (35%; IQR, 27% to 49%) were significantly greater compared with the culprit site in stable patients (neointimal thickness: 0.11 mm [IQR, 0.07 to 0.21 mm], P=0.008; uncovered struts: 9% [IQR, 0% to 39%], P=0.01; fibrin: 36+/-27%, P=0.008; inflammation, 17% [IQR, 7% to 25%], P=0.003) and the nonculprit site within each stent. CONCLUSIONS: Vessel healing at the culprit site in AMI patients treated with DES is substantially delayed compared with the culprit site in patients receiving DES for stable angina, emphasizing the importance of underlying plaque morphology in the arterial response to DES. Our data suggest an increased risk of thrombotic complications in patients treated with DES for AMI.

Predictive factors for in-stent late loss and coronary lesion progression in patients with type 2 diabetes mellitus randomized to rosiglitazone or placebo.

BACKGROUND: Type 2 diabetics (DM2) are at increased risk for restenosis as well as nonculprit coronary artery lesion (NCCL) progression. Rosiglitazone (RSG) favorably modifies many of the altered biologic processes in DM2, although recent reports have questioned its safety. We conducted a double-blind randomized trial to assess the effects of RSG versus placebo on in-stent late lumen loss (LL) and angiographic progression of NCCL. METHODS: A total of 65 DM2 were randomized to RSG (4 mg/d) (n = 32) or placebo (n = 33) at the time of stenting and underwent clinical and laboratory analysis at 1 and 4 months and 8-month angiography (n = 46 patients). Rapid angiographic progression (RAP) was defined as > or =20% diameter reduction of preexisting NCCL by quantitative coronary angiography, or a new narrowing > or =30%. RESULTS: Mean LL in RSG (n = 33 lesions) was not different from that of placebo (0.62 +/- 0.59 vs 0.70 +/- 0.67, P = NS). Seven (13.5%) of 52 NCCLs have RAP in RSG versus 9 (16.1%) of 56 in placebo (P = NS). High-sensitivity C-reactive protein (hs-CRP) was the only predictor of RAP. Patients with a 120-day hs-CRP > or =75th percentile had an OR of 7.35 (95% CI 2.35-23) for RAP versus those below. Although RSG treatment also lowered log (hs-CRP) at 4 months (RSG 0.10 +/- 0.37 vs placebo 0.26 +/- 0.49, P = .06), it did not decrease the likelihood of plaque progression while also raising LDL and N-terminal brain naturetic peptide. CONCLUSIONS: Rosiglitazone appears not to lower LL or reduce angiographic progression of NCCL in DM2 and had complex effects on markers of cardiac risk.

Site-specific targeting of nanoparticle prednisolone reduces in-stent restenosis in a rabbit model of established atheroma.

OBJECTIVE: TRM-484 is a novel drug consisting of nanoparticles of prednisolone with high affinity to chondroitin sulfate proteoglycans (CSPGs). This may allow for neointimal suppression via directed targeting to areas of injury at systemic concentrations low enough to avoid adverse side effects known to occur with oral delivery of steroids. METHODS AND RESULTS: Atherosclerotic New Zealand white Rabbits were implanted with bare metal stents and randomized to receive intravenous TRM-484 at doses of 1 mg/kg or 0.32 mg/kg starting at the day of stenting and continuing 3 times a week for the duration of the study. Control animals received empty liposomes (placebo) or saline infusion. Stented arterial segments were harvested at 42 days and processed for histomorphometry and immunohistochemistry. Tissue and plasma levels were determined along with confocal microscopic analysis to determine distribution of rhodamine-labeled TRM-484 at various time points. TRM-484 was exclusively observed at sites of stent-induced injury, with absence of drug in contralateral nonstented arteries. Tissue concentration of stented arteries exceeded that of contralateral nonstented arteries by 100-fold 24 hours after administration of 1 mg/kg TRM-484 and resulted in significant reduction of percent stenosis compared to saline and placebo treated rabbits (22.5+/-4.4 versus 31.0+/-8.4 and 29.5+/-8.1%, P<0.03). CONCLUSIONS: TRM-484 at doses of 1 mg/kg resulted in significant suppression of in-stent neointimal growth in atherosclerotic rabbits. Site-specific targeting by this nanoparticle steroid in injured atherosclerotic areas might be a valuable and cost-effective approach for the prevention of in-stent restenosis.

Pathological correlates of late drug-eluting stent thrombosis: strut coverage as a marker of endothelialization.

BACKGROUND: Late stent thrombosis (LST) after Cypher and Taxus drug-eluting stent placement has emerged as a major concern. Although the clinical predictors of LST have been reported, specific morphological and histological correlates of LST remain unknown. METHODS AND RESULTS: From a registry totaling 81 human autopsies of drug-eluting stents, 46 (62 lesions) had a drug-eluting stent implanted >30 days. We identified 28 lesions with thrombus and compared those with 34 of similar duration without thrombosis using computer-guided morphometric and histological analyses. LST was defined as an acute thrombus within a coronary artery stent in place >30 days. Multiple logistic generalized estimating equations modeling demonstrated that endothelialization was the best predictor of thrombosis. The morphometric parameter that best correlated with endothelialization was the ratio of uncovered to total stent struts per section. A univariable logistic generalized estimating equations model of occurrence of thrombus in a stent section versus ratio of uncovered to total stent struts per section demonstrated a marked increase in risk for LST as the number of uncovered struts increased. The odds ratio for thrombus in a stent with a ratio of uncovered to total stent struts per section >30% is 9.0 (95% CI, 3.5 to 22). CONCLUSIONS: The most powerful histological predictor of stent thrombosis was endothelial coverage. The best morphometric predictor of LST was the ratio of uncovered to total stent struts. Heterogeneity of healing is a common finding in drug-eluting stents with evidence of LST and demonstrates the importance of incomplete healing of the stented segment in the pathophysiology of LST.

Reperfused myocardial infarction: contrast-enhanced 64-Section CT in comparison to MR imaging.

PURPOSE: To prospectively compare 64-section multidetector computed tomography (CT) and cardiac magnetic resonance (MR) imaging for the early assessment of myocardial enhancement and infarct size after acute reperfused myocardial infarction (MI). MATERIALS AND METHODS: The study was HIPAA compliant and was approved by the institutional review board. All participants gave written informed consent. Twenty-one patients (18 men; mean age, 60 years +/- 13 [standard deviation]) were examined with 64-section multidetector CT and cardiac MR imaging 5 days or fewer after a first reperfused MI. Multidetector CT was performed during the first pass of contrast material to assess myocardial perfusion and detect microvascular obstruction (no reflow). In 15 patients, a second scan was performed 7 minutes later to assess total infarct size by using delayed hyperenhancement. Early hypoenhancement and delayed hyperenhancement were compared between multidetector CT and cardiac MR imaging with Pearson correlation coefficient and Bland-Altman analysis. RESULTS: Early hypoenhancement was recognized on all multidetector CT and cardiac MR images. Delayed hyperenhancement was observed with cardiac MR imaging at all examinations and with multidetector CT at 11 of 15 examinations. While signal intensity differences between hypoperfused and normal myocardium were comparable for first-pass multidetector CT and cardiac MR imaging, cardiac MR imaging had a far better contrast-to-noise ratio (CNR) for delayed acquisitions than did CT (P < .001). Hypoenhanced areas (as a percentage of left ventricular mass) at first-pass multidetector CT (11% +/- 6) correlated well with those at first-pass cardiac MR imaging (7% +/- 4, R(2) = 0.72). Delayed-enhancement multidetector CT (13% +/- 9) correlated well with delayed-enhancement cardiac MR imaging (15% +/- 7, R(2) = 0.55). Quantification of delayed hypoenhancement (n = 12) had very good correlation between multidetector CT (4% +/- 4) and cardiac MR imaging (3% +/- 2) (R(2) = 0.85). CONCLUSION: Early and late hypoenhancement showed good CNR and correlated well between multidetector CT and cardiac MR imaging.

Comprehensive assessment of myocardial perfusion defects, regional wall motion, and left ventricular function by using 64-section multidetector CT.

PURPOSE: To evaluate the accuracy of 64-section multidetector computed tomography (CT) for the assessment of perfusion defects (PDs), regional wall motion (RWM), and global left ventricular (LV) function. MATERIALS AND METHODS: All myocardial infarction (MI) patients signed informed consent. The IRB approved the study and it was HIPAA-compliant. Cardiac multidetector CT was performed in 102 patients (34 with recent acute MI and 68 without). Multidetector CT images were analyzed for myocardial PD, RWM abnormalities, and LV function. Global LV function and RWM were compared with transthoracic echocardiography (TTE) by using multidetector CT. PD was detected by using multidetector CT and was correlated with cardiac biomarkers and single photon emission CT (SPECT) myocardial perfusion imaging. Multidetector CT diagnosis of acute MI was made on the basis of matching the presence of PD with RWM abnormalities compared with clinical evaluation. RESULTS: Correlation between multidetector CT and TTE for global function (r = 0.68) and RWM (kappa = 0.79) was good. The size of PD on multidetector CT had a moderate correlation against SPECT (r = 0.48, -7% +/- 9). There was good to excellent correlation between cardiac biomarkers and the percentage infarct size by using multidetector CT (r = 0.82 for creatinine phosphokinase, r = 0.76 for creatinine phosphokinase of the muscle band, and r = 0.75 for troponin). For detection of acute MI in patients, multidetector CT sensitivity was 94% (32 of 34) and specificity was 97% (66 of 68). Multidetector CT had an excellent interobserver reliability for ejection fraction quantification (r = 0.83), as compared with TTE (r = 0.68). CONCLUSION: Patients with acute MI can be identified by using multidetector CT on the basis of RWM abnormalities and PD.

Vascular responses to drug eluting stents: importance of delayed healing.

Polymer-based sirolimus- (Cypher) and paclitaxel-eluting (Taxus) drug eluting stents have become the treatment of choice for patients with symptomatic coronary artery disease undergoing percutaneous coronary intervention (PCI). Although these stents reduce rates of restenosis compared with bare metal stents (BMS), late thrombosis, a life threatening complication, has emerged as a major safety concern. Our understanding of the pathophysiology of late DES thrombosis is derived from animal and human pathologic samples taken after implantation of these devices. These data indicate that both DES cause substantial impairment in arterial healing characterized by lack of complete reendothelialization and persistence of fibrin when compared with BMS. This delayed healing is the primary substrate underlying all cases of late DES thrombosis at autopsy. Several additional risk factors for late stent thrombosis such as penetration of necrotic core, malapposition, overlapping stent placement, excessive stent length, and bifurcation lesions represent additional barriers to healing and should be avoided if DES are to be used to minimize the risk of late thrombosis. Because the time course of complete healing with DES in man is unknown, the optimal duration of antiplatelet treatment remains to be determined.

Pioglitazone inhibits in-stent restenosis in atherosclerotic rabbits by targeting transforming growth factor-beta and MCP-1.

OBJECTIVE: Although emerging data from preclinical and clinical studies suggests a reduction of in-stent restenosis with peroxisome proliferator-activated receptor (PPAR)-gamma agonists, the reduction of neointimal growth via anti-inflammatory mechanisms has not been explored. METHODS AND RESULTS: Hypercholesterolemic New Zealand White rabbits (n=45) received bilateral balloon-expandable stents implanted into atherosclerotic iliac arteries. Animals were randomized to oral pioglitazone 3 (low dose) or 10 mg/kg per day (high dose) started on the day of stent implantation; control rabbits received placebo. Tissue harvest was performed 28 days after stenting, and stented segments underwent histology, morphometry, immunostaining for macrophages, and scanning electron microscopy. In selected animals, stented arterial segments were placed in organoid culture for 48 hours, and the conditioned media was assayed for 23 different cytokines. There was a 21% reduction in neointimal area for high-dose pioglitazone treated versus placebo rabbits (P<0.005), which was associated with a significant reduction of neointimal macrophages. Analysis of conditioned media revealed an 82% and 74% reduction in the release of monocyte chemoattractant protein-1 (MCP-1) (P<0.007) and transforming growth factor (TGF)-beta1 (P<0.01), respectively, in stented segments from animals treated with 10 mg/kg per day pioglitazone versus placebo. CONCLUSIONS: Oral pioglitazone suppresses in-stent neointimal growth by limiting local inflammatory pathways and may be useful as an adjunctive therapy in patients undergoing percutaneous interventions.

Intraplaque hemorrhage and progression of coronary atheroma.

BACKGROUND: Intraplaque hemorrhage is common in advanced coronary atherosclerotic lesions. The relation between hemorrhage and the vulnerability of plaque to disruption may involve the accumulation of free cholesterol from erythrocyte membranes. METHODS: We stained multiple coronary lesions from 24 randomly selected patients who had died suddenly of coronary causes with an antibody against glycophorin A (a protein specific to erythrocytes that facilitates anion exchange) and Mallory's stain for iron (hemosiderin), markers of previous intraplaque hemorrhage. Coronary lesions were classified as lesions with pathologic intimal thickening, fibrous-cap atheromas with cores in an early or late stage of necrosis, or thin-cap fibrous atheromas (vulnerable plaques). The arterial response to plaque hemorrhage was further defined in a rabbit model of atherosclerosis. RESULTS: Only traces of glycophorin A and iron were found in lesions with pathologic intimal thickening or fibrous-cap atheromas with cores in an early stage of necrosis. In contrast, fibroatheromas with cores in a late stage of necrosis or thin caps had a marked increase in glycophorin A in regions of cholesterol clefts surrounded by iron deposits. Larger amounts of both glycophorin A and iron were associated with larger necrotic cores and greater macrophage infiltration. Rabbit lesions with induced intramural hemorrhage consistently showed cholesterol crystals with erythrocyte fragments, foam cells, and iron deposits. In contrast, control lesions from the same animals had a marked reduction in macrophages and lipid content. CONCLUSIONS: By contributing to the deposition of free cholesterol, macrophage infiltration, and enlargement of the necrotic core, the accumulation of erythrocyte membranes within an atherosclerotic plaque may represent a potent atherogenic stimulus. These factors may increase the risk of plaque destabilization.

Utility of cardiovascular magnetic resonance to predict left ventricular recovery after primary percutaneous coronary intervention for patients presenting with acute ST-segment elevation myocardial infarction.

Cardiac magnetic resonance (CMR) has been shown to predict left ventricular (LV) recovery in patients after acute ST-segment elevation myocardial infarction. The purpose of this investigation was to determine the relative values of infarct transmurality and microvascular obstruction (MVO) using delayed enhancement CMR to predict LV recovery. We studied 17 patients (mean age 60 +/- 10 years, 14 men) presenting with first acute ST-segment elevation myocardial infarction treated with primary percutaneous coronary intervention who underwent CMR within 6 days after presentation and again at 6 months. In total 680 myocardial segments were evaluated, of which 267 (39%) demonstrated delayed hyperenhancement (DHE) and 116 (18%) demonstrated MVO. Unadjusted odds ratio (OR) for any improvement in regional LV function with increasing DHE category (<50%, 51% to 75%, >75% transmurality) was 0.20 (95% confidence interval [CI] 0.13 to 0.30, p <0.0001), whereas it was 0.40 (95% CO 0.28 to 0.55, p <0.0001) with increasing MVO category (0, <50th, >50th percentile). However, when coadjusted together, the relation remained robust with regard to degree of transmurality of DHE (OR 0.21, 95% CI 0.13 to 0.36, p <0.0001), but the relation was lost for MVO (OR 0.90, 95% CI 0.58 to 1.40, p = 0.64). In conclusion, when using the delayed enhancement technique for assessment of DHE and MVO, degree of infarct transmurality appears to be a more powerful predictor of LV recovery by CMR.

Differential response of delayed healing and persistent inflammation at sites of overlapping sirolimus- or paclitaxel-eluting stents.

BACKGROUND: Although effective coverage of challenging coronary lesions has warranted the use of overlapping drug-eluting stents, the histopathological response to stent overlap is unknown. METHODS AND RESULTS: The arterial reaction to overlapping Cypher or Taxus drug-eluting stents was examined in rabbits with bare metal stents, BxVelocity or Express, serving as controls. Single iliac artery balloon injury was followed by placement of 2 overlapping 3.0-mm-diameter drug-eluting stents or bare metal stents in 60 animals (mean length of overlap, 9.8+/-3.6 mm). Stented arteries were harvested at 28 and 90 days for histology. Overlapped segments exhibited delayed healing compared with proximal and distal nonoverlapping sites at 28 days. Overlapped segments in Taxus stents induced significantly more luminal heterophils/eosinophils and fibrin deposition than Cypher; peristrut giant cell infiltration, however, was more frequent in the latter. Overlapping bare metal stents also showed mild delayed healing compared with nonoverlapped segments, but not to the same extent as drug-eluting stents. Although neointimal thickness within the overlap was similar in 28- and 90-day Cypher stents, there was a significant increase with Taxus (P=0.03). CONCLUSIONS: Compared with bare metal stents, drug-eluting stents further delay arterial healing and promote inflammation at sites of overlap. Taxus stents induced greater fibrin deposition, medial cell loss, heterophils/eosinophils, and late neointimal hyperplasia. Patients receiving overlapping drug-eluting stents need more frequent follow-up than patients with nonoverlapping stents.

Drug-eluting stents for diabetes mellitus: a rush to judgment?

The two pivotal U.S. trials of drug-eluting stents do not establish the principle that these stents are superior to thin-strut bare-metal stents for preventing repeat revascularization in patients with diabetes. Neither study was adequately powered to make this determination. Moreover, both studies used thick-strut stents known to have high restenosis rates as controls. Low angiographic follow-up underestimates the true target lesion revascularization rate in the Polymer-Based Paclitaxel-Eluting Stent in Patients with Coronary Artery Disease (TAXUS-IV) trial because of the high incidence of silent ischemia in patients with diabetes. Optimal therapy for diabetic coronary disease should include a comprehensive approach directed toward metabolic normalization in addition to local stent-based therapy.

Differentiation of recent and chronic myocardial infarction by cardiac computed tomography.

Clinical use of cardiac computed tomography is rapidly expanding, and its purpose may reach beyond noninvasive coronary angiography. We investigated the ability of 64-slice multidetector computed tomography to differentiate between recent and long-standing myocardial infarction (MI). Contrast-enhanced coronary computed tomographic (CT) scans (Siemens Sensation 64) of patients with a recent MI (< 7 days, n = 16), long-standing MI (> 12 months, n = 13), and no MI (n = 13) were retrospectively evaluated. To anticipate transmural variation of myocardial perfusion and to neutralize image noise, a series of thin, overlapping slices was created in parallel alignment to the myocardial wall. Within each of these slices, a small region of interest was placed at a constant in-plane position to measure the CT attenuation (Hounsfield units [HU]) at consecutive transmural locations of injured and normal remote myocardium. In addition, wall thickness and the myocardial cavity were measured. Significantly lower CT attenuation values were found in patients with long-standing MI (-13 +/- 37 HU) than in those with acute MI (26 +/- 26 HU) and normal controls (73 +/- 14 HU, p < 0.001). The attenuation difference between infarcted and remote myocardia was larger in patients with long-standing MI than in patients with recent MI (89 +/- 41 and 55 +/- 33 HU, respectively, p < 0.001). In addition, long-standing MI was associated with wall thinning (p < 0.01), and ventricular dilation (p < 0.05), whereas recent MI was not (p > 0.05). In conclusion, recent and long-standing MIs may be differentiated by computed tomography based on myocardial CT attenuation values and ventricular dimensions.

Atherosclerotic plaque progression and vulnerability to rupture: angiogenesis as a source of intraplaque hemorrhage.

Observational studies of necrotic core progression identify intraplaque hemorrhage as a critical factor in atherosclerotic plaque growth and destabilization. The rapid accumulation of erythrocyte membranes causes an abrupt change in plaque substrate characterized by increased free cholesterol within the lipid core and excessive macrophage infiltration. Neoangiogenesis is associated closely with plaque progression, and microvascular incompetence is a likely source of intraplaque hemorrhage. Intimal neovascularization is predominantly thought to arise from the adventitia, where there are a plethora of pre-existing vasa vasorum. In lesions that have early necrotic cores, the majority of vessels invading from the adventitia occur at specific sites of medial wall disruption. A breech in the medial wall likely facilitates the rapid in-growth of microvessels from the adventitia, and exposure to an atherosclerotic environment stimulates abnormal vascular development characterized by disorganized branching and immature endothelial tubes with "leaky" imperfect linings. This network of immature blood vessels is a viable source of intraplaque hemorrhage providing erythrocyte-derived phospholipids and free cholesterol. The rapid change in plaque substrate caused by the excessive accumulation of erythrocytes may promote the transition from a stable to an unstable lesion. This review discusses the potential role of intraplaque vasa vasorum in lesion instability as it relates to plaque rupture.

Cardiopulmonary bypass induces release of soluble CD40 ligand.

BACKGROUND: Cardiopulmonary bypass (CPB) is known to induce platelet activation, thrombosis, thrombocytopenia, and a systemic inflammatory response. It is known that CD40 ligand (CD40L) exists in platelets, that a soluble form of this protein (sCD40L) is released on platelet activation, that platelets are the primary source of sCD40L in blood, and that sCD40L is involved in thrombosis and inflammation. The present study was designed to determine whether sCD40L is released during CPB. Methods and Results- Blood was obtained from patients undergoing CPB-requiring surgery and analyzed for sCD40L, interleukin-6, and platelet factor 4 and beta-thromboglobulin (markers of platelet activation). Platelets were also isolated and analyzed for their levels of CD40L. Plasma levels of sCD40L increased >1.7-fold (from 0.29 to 0.51 ng/mL, P=0.001) within 1 hour on CPB and increased further to 3.7-fold (to 1.08 ng/mL, P=0.03) 2 hours after the procedure. Half of the released sCD40L was cleared in 2 hours, which allowed the sCD40L to return to approximately baseline levels 8 hours after the procedure. The platelet content of CD40L was decreased by 40% (2.675 to 1.64 ng/10(8) platelets, P=0.001) 1 hour after initiation of CPB and was similar to that observed for platelet factor 4 and beta-thromboglobulin. Interleukin-6, a marker of inflammation, also increased during CPB. CONCLUSIONS: The present study demonstrates that CPB causes an increase in the concentration of plasma sCD40L. The corresponding decrease in platelet CD40L suggests that this prothrombotic and proinflammatory protein was derived primarily from platelets and may contribute to the thrombotic and inflammatory complications associated with CPB.

Targeting of apoptotic macrophages and experimental atheroma with radiolabeled annexin V: a technique with potential for noninvasive imaging of vulnerable plaque.

BACKGROUND: Apoptosis is common in advanced human atheroma and contributes to plaque instability. Because annexin V has a high affinity for exposed phosphatidylserine on apoptotic cells, radiolabeled annexin V may be used for noninvasive detection of apoptosis in atherosclerotic lesions. METHODS AND RESULTS: Atherosclerotic plaques were produced in 5 rabbits by deendothelialization of the infradiaphragmatic aorta followed by 12 weeks of cholesterol diet; 5 controls were studied without manipulation. Animals were injected with human recombinant annexin V labeled with technetium-99m before imaging. Aortas were explanted for ex vivo imaging, macroautoradiography, and histological characterization of plaque. Radiolabeled annexin V cleared rapidly from the circulation (T1/2, alpha 9 and beta 46 minutes). There was intense uptake of radiolabel within lesions by 2 hours; no uptake was seen in controls. The results were confirmed in the ex vivo imaging of the explanted aorta. Quantitative annexin uptake was 9.3-fold higher in lesion versus nonlesion areas; the lesion-to-blood ratio was 3.0+/-0.37. Annexin uptake paralleled lesion severity and macrophage burden; no correlation was observed with smooth muscle cells. DNA fragmentation staining of apoptotic nuclei was increased in advanced lesions with evolving necrotic cores, predominantly in macrophages; the uptake of radiolabel correlated with the apoptotic index. CONCLUSIONS: Because annexin V clears rapidly from blood and targets apoptotic macrophage population, it should constitute an attractive imaging agent for the noninvasive detection of unstable atherosclerotic plaques.

Major depression is associated with significant diurnal elevations in plasma interleukin-6 levels, a shift of its circadian rhythm, and loss of physiological complexity in its secretion: clinical implications.

BACKGROUND: Major depressive disorder (MDD) is associated with increased risk for premature coronary heart disease and bone loss. Single time measurements of plasma IL-6, a good predictor of future risk for both cardiovascular disease and osteoporosis, revealed significant elevations in depressed patients. The objective of this study was to rigorously compare plasma IL-6 levels, measured over 24 h, in MDD patients and healthy controls. Given the activating role of IL-6 on the hypothalamic-pituitary-adrenal (HPA) axis, and the relevance of its dysregulation in MDD, we also analyzed the relations between IL-6 and cortisol levels. METHODS: We studied nine patients and nine controls, individually matched by gender, age (+/-5 yr), body mass index (+/-2 kg/m2), and menstrual cycle phase. Diagnosis of MDD was confirmed by structured clinical interview based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Axis I diagnostic criteria. Self-reported mood ratings were assessed by multiple visual analog scales. The rhythmicity and complexity of IL-6 and cortisol secretion were tested by cosinor analyses, approximate entropy (ApEn) and cross-ApEn algorithms. RESULTS: MDD patients had significant mean IL-6 elevations from 1000-1200 h and at 1500 h (P ranging from <0.05 to <0.01) vs. controls. In addition, in MDD, the circadian rhythm of IL-6 was shifted by 12 h, and its physiological complexity was reduced, with no difference in the cross-ApEn of IL-6 and cortisol between the two groups, and significant time-lagged correlations only in the controls. IL-6 levels correlated significantly with mood ratings. CONCLUSIONS: We report profound morning elevations of plasma IL-6 and a reversal of its circadian rhythm in MDD patients, in the absence of hypercortisolism. These findings may be relevant to the increased risk for coronary heart disease and bone loss in MDD.

Enhanced extracellular matrix accumulation in restenosis of coronary arteries after stent deployment.

OBJECTIVES: The goal of this study was to evaluate the cellular and extracellular composition of human coronary arterial in-stent restenosis after various periods of time following stent deployment. BACKGROUND: Neointimal in-growth rather than stent recoil is thought to be important for coronary arterial in-stent restenosis. There is only limited data on the cellular and extracellular composition changes with time after stent deployment. METHODS: We analyzed 29 coronary arterial in-stent restenotic tissue samples (14 left anterior descending coronary artery, 10 right coronary artery, and 5 left circumflex artery) retrieved by using directional coronary atherectomy from 25 patients at 0.5 to 23 (mean, 5.7) months after deployment of Palmaz-Schatz stents employing histochemical and immunocytochemical techniques. RESULTS: Cell proliferation was low (0% to 4%). Myxoid tissue containing extracellular matrix (ECM) enriched with proteoglycans was found in 69% of cases and decreased over time after stenting. Cell-depleted areas were found in 57% of cases and increased with time after stenting. Versican, biglycan, perlecan, and hyaluronan were present with varying individual distributions in all samples. Positive transforming growth factor-beta1 staining was found in 80% of cases. Immunostaining with alpha-smooth muscle actin identified the majority of cells as smooth muscle cells with occasional macrophages present (< or =12 cells per section). CONCLUSIONS: These data suggest that enhanced ECM accumulation rather than cell proliferation contribute to later stages of in-stent restenosis. Balloon angioplasty of in-stent restenosis may, therefore, fail due to ECM changes during: 1) additional stent expansion, 2) tissue extrusion out of the stent, or 3) tissue compression.

Short-term intravenous eptifibatide infusion combined with reduced dose recombinant tissue plasminogen activator inhibits platelet recruitment at sites of coronary artery injury.

OBJECTIVES: This study was designed to determine in a dog model of coronary thrombosis whether short-term eptifibatide (Ep) combined with low-dose plasminogen activator (rt-PA) inhibits platelet recruitment at sites of endothelial damage after normalization of platelet function. BACKGROUND: Ep plus reduced-dose rt-PA has not previously been shown to render a recanalized coronary artery resistant to platelet recruitment after normalization of platelet function. METHOD: Inhibition of platelet recruitment was studied by scanning electron microscopy (SEM) in a canine model of left anterior descending (LAD) thrombosis. In phase I treatment groups were: 1) Ep (n = 6); 2) Ep + rt-PA (n = 6); 3) rt-PA (n = 6); and 4) placebo (n = 4). Coronary blood flow was monitored and LAD segments excised for SEM after 90-min infusion of study drug. In phase II, dogs were randomized to Ep alone (n = 5) or to Ep + rt-PA (n = 5). Coronary blood flow was monitored during and 120 min after cessation of drug when platelet function had returned to normal and LAD segments were excised. RESULTS: All animals except placebo showed reflow. In phase I, SEM showed an absence of platelet aggregates with Ep alone and with Ep + rt-PA, but not with rt-PA alone. In phase II, SEM showed an intimal surface devoid of mural thrombus and platelet aggregates only in Ep + rt-PA treated arteries. Ep-alone treated arteries showed new platelet aggregates at sites of residual mural thrombus. CONCLUSIONS: Short-term infusion Ep plus low-dose rt-PA acutely neutralizes the ability of damaged endothelial surfaces to recruit new platelets by inhibiting platelet aggregation and eliminating residual mural thrombus.