Daniel I. Simon

Twelve or 30 Months of Dual Antiplatelet Therapy after Drug-Eluting Stents

BACKGROUND Dual antiplatelet therapy is recommended after coronary stenting to prevent thrombotic complications, yet the benefits and risks of treatment beyond 1 year are uncertain. METHODS Patients were enrolled after they had undergone a coronary stent procedure in which a drug-eluting stent was placed. After 12 months of treatment with a thienopyridine drug (clopidogrel or prasugrel) and aspirin, patients were randomly assigned to continue receiving thienopyridine treatment or to receive placebo for another 18 months; all patients continued receiving aspirin. The coprimary efficacy end points were stent thrombosis and major adverse cardiovascular and cerebrovascular events (a composite of death, myocardial infarction, or stroke) during the period from 12 to 30 months. The primary safety end point was moderate or severe bleeding. RESULTS A total of 9961 patients were randomly assigned to continue thienopyridine treatment or to receive placebo. Continued treatment with thienopyridine, as compared with placebo, reduced the rates of stent thrombosis (0.4% vs. 1.4%; hazard ratio, 0.29 [95% confidence interval {CI}, 0.17 to 0.48]; P<0.001) and major adverse cardiovascular and cerebrovascular events (4.3% vs. 5.9%; hazard ratio, 0.71 [95% CI, 0.59 to 0.85]; P<0.001). The rate of myocardial infarction was lower with thienopyridine treatment than with placebo (2.1% vs. 4.1%; hazard ratio, 0.47; P<0.001). The rate of death from any cause was 2.0% in the group that continued thienopyridine therapy and 1.5% in the placebo group (hazard ratio, 1.36 [95% CI, 1.00 to 1.85]; P=0.05). The rate of moderate or severe bleeding was increased with continued thienopyridine treatment (2.5% vs. 1.6%, P=0.001). An elevated risk of stent thrombosis and myocardial infarction was observed in both groups during the 3 months after discontinuation of thienopyridine treatment. CONCLUSIONS Dual antiplatelet therapy beyond 1 year after placement of a drug-eluting stent, as compared with aspirin therapy alone, significantly reduced the risks of stent thrombosis and major adverse cardiovascular and cerebrovascular events but was associated with an increased risk of bleeding. (Funded by a consortium of eight device and drug manufacturers and others; DAPT ClinicalTrials.gov number, NCT00977938.).

Regulation of Integrin Function by the Urokinase Receptor

Integrin function is central to inflammation, immunity, and tumor progression. The urokinase-type plasminogen activator receptor (uPAR) and integrins formed stable complexes that both inhibited native integrin adhesive function and promoted adhesion to vitronectin via a ligand binding site on uPAR. Interaction of soluble uPAR with the active conformer of integrins mimicked the inhibitory effects of membrane uPAR. Both uPAR-mediated adhesion and altered integrin function were blocked by a peptide that bound to uPAR and disrupted complexes. These data provide a paradigm for regulation of integrins in which a nonintegrin membrane receptor interacts with and modifies the function of activated integrins.

Inflammation and Thrombosis The Clot Thickens

Textbooks often portray thrombosis as a bland protective mechanism critical for stanching blood loss after injury: the prick of a lancet, the wound of a scalpel, or the predator’s fangs neatly trigger a proteolytic cascade culminating in fibrin formation and cross-linking. However, in diseases such as atherosclerosis, the picture differs substantially from this simplistic model. In the natural history of atherosclerosis, thrombosis involves an inciting injury more subtle than a wound. In such pathological states, the importance of an intricate interface between inflammation and thrombosis becomes apparent. Consider the case of septic shock, a dramatic example of the link between inflammation and thrombosis. When Gram-negative bacteria release their endotoxin into the bloodstream, the lipopolysaccharide can change endothelial lining of blood vessels from an anticoagulant, profibrinolytic surface into one that promotes thrombosis. Bacterial endotoxin potently stimulates expression of the gene encoding tissue factor, a procoagulant molecule that multiplies manyfold the activity of coagulation factors VIIa and Xa. Endotoxin also can augment endothelial cell production of fibrinolytic inhibitor plasminogen activator inhibitor-1 (PAI-1). These alterations in endothelial function lead to the frequent clinical scenario of disseminated intravascular coagulation, a common concomitant of Gram-negative sepsis. Less-global endothelial activation may contribute to thrombosis in situ in more-chronic diseases such as atherosclerosis. Many inflammatory mediators found in human atherosclerotic plaques can augment tissue factor gene expression by endothelial cells. For example, interleukin-1 (IL-1) or tumor necrosis factor not only augment tissue factor gene expression but also PAI-1 production by human endothelial cells. Bacterial endotoxins within atheroma conceivably could derive from local …

Intracoronary Optical Coherence Tomography: A Comprehensive Review: Clinical and Research Applications

Cardiovascular optical coherence tomography (OCT) is a catheter-based invasive imaging system. Using light rather than ultrasound, OCT produces high-resolution in vivo images of coronary arteries and deployed stents. This comprehensive review will assist practicing interventional cardiologists in understanding the technical aspects of OCT based upon the physics of light and will also highlight the emerging research and clinical applications of OCT. Semi-automated imaging analyses of OCT systems permit accurate measurements of luminal architecture and provide insights regarding stent apposition, overlap, neointimal thickening, and, in the case of bioabsorbable stents, information regarding the time course of stent dissolution. The advantages and limitations of this new imaging modality will be discussed with emphasis on key physical and technical aspects of intracoronary image acquisition, current applications, definitions, pitfalls, and future directions.

Molecular Basis of Restenosis and Drug-Eluting Stents

Resolution of restenosis probably requires both creation of the largest possible residual lumen and substantial inhibition of intimal hyperplasia . — J.S. Forrester and coworkers1 Dr Forrester’s prediction that resolution of restenosis would require the translational merging of molecular mechanisms of proliferation with local scaffolding and drug-delivery devices appears to have been remarkably prescient. The application of drug-eluting stent (DES) technology to improve clinical outcomes after percutaneous coronary intervention (PCI) represents one of the greatest success stories in cardiology. This review highlights the molecular basis of restenosis and DES for the clinical and interventional cardiologist and vascular biologist. Restenosis is the arterial wall’s healing response to mechanical injury and comprises 2 main processes—neointimal hyperplasia (ie, smooth muscle migration/proliferation, extracellular matrix deposition) and vessel remodeling. Primarily on the basis of observations from animal studies, Forrester and coworkers1 proposed a paradigm for neointimal hyperplasia as a general wound-healing response. Platelet aggregation, inflammatory cell infiltration, release of growth factors, medial smooth muscle cell (SMC) modulation and proliferation, proteoglycan deposition, and extracellular matrix remodeling were identified as the major milestones in the temporal sequence of this response. This view of the neointimal hyperplasia process was modified subsequently by Libby and colleagues2 to reconcile certain important clinical features—namely, that thrombosis, often invoked as a cause of SMC proliferation, wanes before intimal thickening peaks and that antithrombotic therapy failed to eliminate restenosis. In this cascade model, a special case was made for the centrality of inflammation, and it was proposed that autocrine or paracrine mediators (eg, interleukin-1 [IL-1] and tumor necrosis factor), the expressions of which are triggered by vascular injury, contribute to deranged SMC behavior during restenosis. The molecular mechanisms of the arterial remodeling are less well understood. The term remodeling has been applied largely to describe either vascular shrinkage or enlargement. …

Effect of Intracoronary Delivery of Autologous Bone Marrow Mononuclear Cells 2 to 3 Weeks Following Acute Myocardial Infarction on Left Ventricular Function The LateTIME Randomized Trial

CONTEXT Clinical trial results suggest that intracoronary delivery of autologous bone marrow mononuclear cells (BMCs) may improve left ventricular (LV) function when administered within the first week following myocardial infarction (MI). However, because a substantial number of patients may not present for early cell delivery, the efficacy of autologous BMC delivery 2 to 3 weeks post-MI warrants investigation. OBJECTIVE To determine if intracoronary delivery of autologous BMCs improves global and regional LV function when delivered 2 to 3 weeks following first MI. DESIGN, SETTING, AND PATIENTS A randomized, double-blind, placebo-controlled trial (LateTIME) of the National Heart, Lung, and Blood Institute-sponsored Cardiovascular Cell Therapy Research Network of 87 patients with significant LV dysfunction (LV ejection fraction [LVEF] ≤45%) following successful primary percutaneous coronary intervention (PCI) between July 8, 2008, and February 28, 2011. INTERVENTIONS Intracoronary infusion of 150 × 10(6) autologous BMCs (total nucleated cells) or placebo (BMC:placebo, 2:1) was performed within 12 hours of bone marrow aspiration after local automated cell processing. MAIN OUTCOME MEASURES Changes in global (LVEF) and regional (wall motion) LV function in the infarct and border zone between baseline and 6 months, measured by cardiac magnetic resonance imaging. Secondary end points included changes in LV volumes and infarct size. RESULTS A total of 87 patients were randomized (mean [SD] age, 57 [11] years; 83% men). Harvesting, processing, and intracoronary delivery of BMCs in this setting was feasible. Change between baseline and 6 months in the BMC group vs placebo for mean LVEF (48.7% to 49.2% vs 45.3% to 48.8%; between-group mean difference, -3.00; 95% CI, -7.05 to 0.95), wall motion in the infarct zone (6.2 to 6.5 mm vs 4.9 to 5.9 mm; between-group mean difference, -0.70; 95% CI, -2.78 to 1.34), and wall motion in the border zone (16.0 to 16.6 mm vs 16.1 to 19.3 mm; between-group mean difference, -2.60; 95% CI, -6.03 to 0.77) were not statistically significant. No significant change in LV volumes and infarct volumes was observed; both groups decreased by a similar amount at 6 months vs baseline. CONCLUSION Among patients with MI and LV dysfunction following reperfusion with PCI, intracoronary infusion of autologous BMCs vs intracoronary placebo infusion, 2 to 3 weeks after PCI, did not improve global or regional function at 6 months. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00684060.

Angiotensin-receptor blockade and risk of cancer: meta-analysis of randomised controlled trials

BACKGROUND Angiotensin-receptor blockers (ARBs) are a widely used drug class approved for treatment of hypertension, heart failure, diabetic nephropathy, and, recently, for cardiovascular risk reduction. Experimental studies implicate the renin-angiotensin system, particularly angiotensin II type-1 and type-2 receptors, in the regulation of cell proliferation, angiogenesis, and tumour progression. We assessed whether ARBs affect cancer occurrence with a meta-analysis of randomised controlled trials of these drugs. METHODS We searched Medline, Scopus (including Embase), Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and the US Food and Drug Administration website for studies published before November, 2009, that included any of the seven currently available ARBs. Randomised controlled trials with an ARB given in at least one group, with a follow-up of at least 1 year, and that enrolled at least 100 patients were included. New-cancer data were available for 61,590 patients from five trials. Data on common types of solid organ cancers were available for 68,402 patients from five trials, and data on cancer deaths were available for 93,515 patients from eight trials. FINDINGS Telmisartan was the study drug in 30,014 (85.7%) patients who received ARBs as part of the trials with new cancer data. Patients randomly assigned to receive ARBs had a significantly increased risk of new cancer occurrence compared with patients in control groups (7.2%vs 6.0%, risk ratio [RR] 1.08, 95% CI 1.01-1.15; p=0.016). When analysis was limited to trials where cancer was a prespecified endpoint, the RR was 1.11 (95% CI 1.04-1.18, p=0.001). Among specific solid organ cancers examined, only new lung-cancer occurrence was significantly higher in patients randomly assigned to receive ARBs than in those assigned to receive control (0.9%vs 0.7%, RR 1.25, 1.05-1.49; p=0.01). No statistically significant difference in cancer deaths was observed (1.8%vs 1.6%, RR 1.07, 0.97-1.18; p=0.183). INTERPRETATION This meta-analysis of randomised controlled trials suggests that ARBs are associated with a modestly increased risk of new cancer diagnosis. Given the limited data, it is not possible to draw conclusions about the exact risk of cancer associated with each particular drug. These findings warrant further investigation.

Vascular Inflammation and Repair: Implications for Re-Endothelialization, Restenosis, and Stent Thrombosis

The cellular and molecular processes that control vascular injury responses after percutaneous coronary intervention involve a complex interplay among vascular cells and progenitor cells that control arterial remodeling, neointimal proliferation, and re-endothelialization. Drug-eluting stents (DES) improve the efficacy of percutaneous coronary intervention by modulating vascular inflammation and preventing neointimal proliferation and restenosis. Although positive effects of DES reduce inflammation and restenosis, negative effects delay re-endothelialization and impair endothelial function. Delayed re-endothelialization and impaired endothelial function are linked to stent thrombosis and adverse clinical outcomes after DES use. Compared with bare-metal stents, DES also differentially modulate mobilization, homing, and differentiation of vascular progenitor cells involved in re-endothelialization and neointimal proliferation. The effects of DES on vascular inflammation and repair directly impact clinical outcomes with these devices and dictate requirements for extended-duration dual antiplatelet therapy.

Effect of QRS morphology on clinical event reduction with cardiac resynchronization therapy: meta-analysis of randomized controlled trials.

BACKGROUND Cardiac resynchronization therapy (CRT) is effective in reducing clinical events in systolic heart failure patients with a wide QRS. Previous retrospective studies suggest only patients with QRS prolongation due to a left bundle-branch block (LBBB) benefit from CRT. Our objective was to examine this by performing a meta-analysis of all randomized controlled trials of CRT. METHODS Systematic searches of MEDLINE and the Food and Drug Administration official website were conducted for randomized controlled CRT trials. Trials reporting adverse clinical events (eg, all-cause mortality, heart failure hospitalizations) according to QRS morphology were included in the meta-analysis. RESULTS Four randomized trials totaling 5,356 patients met the inclusion criteria. In patients with LBBB at baseline, there was a highly significant reduction in composite adverse clinical events with CRT (RR = 0.64 [95% CI (0.52-0.77)], P = .00001). However no such benefit was observed for patients with non-LBBB conduction abnormalities (RR = 0.97 [95% CI (0.82-1.15)], P = .75). When examined separately, there was no benefit in patients with right-bundle branch block (RR = 0.91 [95% CI (0.69-1.20)], P = .49) or non-specific intraventricular conduction delay (RR = 1.19 [95% CI (0.87-1.63)], P = .28). There was no heterogeneity among the clinical trials with regards to the lack of benefit in non-LBBB patients (I(2) = 0%). When directly compared, the difference in effect of CRT between LBBB versus non-LBBB patients was highly statistically significant (P = .0001 by heterogeneity analysis). CONCLUSIONS While CRT was very effective in reducing clinical events in patients with LBBB, it did not reduce such events in patients with wide QRS due to other conduction abnormalities.

Myeloid-Related Protein-8/14 Is Critical for the Biological Response to Vascular Injury

Background— Myeloid-related protein (MRP)-8 (S100A8) and MRP-14 (S100A9) are members of the S100 family of calcium-modulated proteins that regulate myeloid cell function and control inflammation, in part, through activation of Toll-like receptor-4 and the receptor for advanced glycation end products. A transcriptional profiling approach in patients with acute coronary syndromes identified MRP-14 as a novel predictor of myocardial infarction. Further studies demonstrated that elevated plasma levels of MRP-8/14 heterodimer predict increased risk of first and recurrent cardiovascular events. Beyond its serving as a risk marker, whether MRP-8/14 participates directly in vascular inflammation and disease remains unclear. Methods and Results— We evaluated vascular inflammation in wild-type and MRP-14–deficient (MRP-14−/−) mice that lack MRP-8/14 complexes with experimental arterial injury, vasculitis, or atherosclerosis. After femoral artery wire injury, MRP-14−/− mice had significant reductions in leukocyte accumulation, cellular proliferation, and neointimal formation compared with wild-type mice. In a cytokine-induced local Shwartzman-like reaction that produces thrombohemorrhagic vasculitis, MRP-14−/− mice had significant reductions in neutrophil accumulation, lesion severity, and hemorrhagic area. In response to high-fat feeding, mice doubly deficient in apolipoprotein E and MRP-8/14 complexes had attenuation in atherosclerotic lesion area and in macrophage accumulation in plaques compared with mice deficient in apolipoprotein E alone. Conclusion— This study demonstrates that MRP-8/14 broadly regulates vascular inflammation and contributes to the biological response to vascular injury by promoting leukocyte recruitment.