Antithrombotic therapy and the transition to the catheterization laboratory in UA/NSTEMI.

The management of unstable angina/non ST elevation myocardial infarction (UA/NSTEMI) has evolved substantially in recent years. Multiple new antithrombotic options are available; in addition, the use of interventional strategies in patients with UA/NSTEMI has become the dominant strategy, particularly in tertiary centers. On the one hand, we are doing more percutaneous interventions more rapidly in ACS patients. On the other hand, we have an ever-expanding therapeutic armamentarium to apply in these complex clinical circumstances. Much of the controversy surrounding modern-day management is not so much about the specific the choice of agent or strategy, but rather how to use these agents most effectively in a clinical environment where patients may come forward to the catheterization laboratory, sometimes rapidly, and may require percutaneous or surgical revascularization. All available antithrombotic agents act on one (or more) of the four steps of coagulation: platelet activation, platelet aggregation, thrombin generation, and thrombin activity. The antiplatelet agents, aspirin, thieno-pyridines, and glycoprotein (GP) IIb/IIIa antagonists, target the early steps of platelet activation and aggregation. The antithrombin agents, unfractionated heparin, low molecular weight (LMW) heparin, Xa inhibitors, and direct thrombin antagonists, act specifically to target thrombin generation, thrombin activity, or both. We will review the major recent trials that comprise the current state of knowledge regarding these new antithrombotic agents in ACS, and discuss some of the near-future additions to our armamentarium, including prasugrel, Cangrelor, and AZD6140. The most recent ACC/AHA and ESC unstable angina guidelines have emphasized that multiple options are available, and no one agent can be recommended over the others in all cases. There is NOT one perfect antithrombotic regimen for all patients. Antithrombotic therapy needs to be individualized, and that so-called ''standard'' therapy may need to be supplemented (or even replaced) in specific circumstances. Ultimately, determining optimal therapy means understanding the physiology, understanding the therapeutic options - not just how they work, but how they may work together, and being able to interpret a never-ending supply of new clinical trial data that have to be applied in the ''real world''.

Optimal antithrombotic treatment for percutaneous coronary intervention.

Recent years have witnessed significant advances in the percutaneous treatment of patients with atherosclerotic vascular disease. Anti-platelet and anti-thrombotic agents are routinely administered to minimize the risk of peri-procedural myonecrosis, stent thrombosis and other procedural complications. This article presents a current view of optimal adjunctive antithrombotic therapy for percutaneous coronary interventions (PCI), recognizing that optimal is a necessarily subjective label. This article focuses specifically on anticoagulant agents such as unfractionated heparin (UFH), the low-molecular weight heparins (LMWH), and direct thrombin inhibitors, and antiplatelet agents, such as aspirin, thienopyridines, and glycoprotein IIb/IIIa antagonists. It starts with a general discussion of anticoagulation and percutaneous intervention, followed by a summary of the modern-day view of the coagulation process. The mechanism of action of the individual agents is then presented, followed by some of the evidence base of recent clinical trials of anticoagulant and antiplatelet agents in PCI. Finally, we present summary recommendations for procedural anticoagulation in low risk, not-low risk, and high risk PCI, and list what we feel are appropriate doses for the agents employed. Ultimately, though, it is the individual interventional cardiologists who must decide for themselves exactly what constitutes optimal antithrombotic therapy for PCI.

Selective serotonin reuptake inhibitors yield additional antiplatelet protection in patients with congestive heart failure treated with antecedent aspirin.

Clinical depression has been identified as an independent risk factor for increased mortality in patients with coronary artery disease. Enhanced platelet activity has been suggested as the mechanism responsible for this adverse association. Selective serotonin reuptake inhibitors (SSRIs) are known to inhibit platelets in patients undergoing coronary stenting. We sought to determine whether concomitant therapy with SSRIs would yield additional anti-platelet benefit in patients with congestive heart failure (CHF) already treated with antecedent aspirin. A total of 88 patients with left ventricular ejection fraction (LVEF) <40% or CHF symptoms in the setting of preserved systolic function and NYHA Class II-IV were analyzed. Of these, 23 patients (26%) were chronic SSRI users (SSRI+), and 65 patients were free from SSRI therapy (SSRI-). All patients received aspirin (325 mg) for at least 1 month prior to platelet studies. Platelets were assessed by aggregometry, flow cytometry and a rapid analyzer. The SSRI+ group exhibited a substantial decrease in platelet activity when compared with SSRI- patients, as manifested by a significant reduction in ADP- (P=0.001), and collagen-induced (P=0.02) aggregation, and the expression of PECAM-1 (P=0.03), GPIb (P=0.03), GP IIb/IIIa antigen (P=0.02) and GP IIb/IIIa activity with PAC-1 antibody (P=0.04) and P-selectin (P=0.02). Therapy with SSRIs also resulted in the reduced formation of platelet-leukocyte microparticles (P=0.01). Epinephrine-induced aggregation in plasma, collagen-induced whole blood aggregation, closure time and expression of vitronectin receptor, CD63, CD107a, CD107b and CD151 did not differ between groups. In patients with CHF already on aspirin, SSRI therapy was associated with further inhibition of platelet function. This observation may help to explain some of the clinical benefits associated with SSRI therapy. Further clinical trials may help to elucidate the potential outcome benefits of SSRIs in other potential thrombotic circumstances.

The current practice of intra-aortic balloon counterpulsation: results from the Benchmark Registry.

OBJECTIVES: This study presents clinical data from the first large registry of aortic counterpulsation, a computerized database that incorporates prospectively gathered data on indications for intra-aortic balloon counterpulsation (IABP) use, patient demographics, concomitant medication and in-hospital outcomes and complications. BACKGROUND: The intra-aortic balloon pump (IABP) is widely used to provide circulatory support for patients experiencing hemodynamic instability due to myocardial infarction, cardiogenic shock, or in very high risk patients undergoing angioplasty or coronary artery bypass grafting. METHODS: Between June 1996 and August 2000, 203 hospitals worldwide (90% U.S., 10% non-U.S.) collected 16,909 patient case records (68.8% men, 31.2% women; mean age 65.9 +/- 11.7 years). RESULTS: The most frequent indications for use of IABP were as follows: to provide hemodynamic support during or after cardiac catheterization (20.6%), cardiogenic shock (18.8%), weaning from cardiopulmonary bypass (16.1%), preoperative use in high risk patients (13.0%) and refractory unstable angina (12.3%). Major IABP complications (major limb ischemia, severe bleeding, balloon leak, death directly due to IABP insertion or failure) occurred in 2.6% of cases; in-hospital mortality was 21.2% (11.6% with the balloon in place). Female gender, high age and peripheral vascular disease were independent predictors of a serious complication. CONCLUSIONS: This registry provides a useful tool for monitoring the evolving practice of IABP. In the modern-day practice of IABP, complication rates are generally low, although in-hospital mortality remains high. There is an increased risk of major complications in women, older patients and patients with peripheral vascular disease.

Long-term mortality benefit with abciximab in patients undergoing percutaneous coronary intervention.

OBJECTIVES: The goal of this study was to test: 1) if platelet glycoprotein IIb/IIIa (GP IIb/IIIa) blockade with abciximab bolus plus 12-h infusion reduces mortality after percutaneous coronary intervention (PCI); 2) if prevention of early myocardial infarction (MI) after PCI is a mechanism for reducing mortality; and 3) for risk factors for mortality after PCI. BACKGROUND: Studies of PCI suggest that MI after intervention is predictive of mortality. Abciximab, a platelet GP IIb/IIIa receptor inhibitor, has consistently reduced the incidence of MI among PCI patients in several trials. The presumed mechanism is prevention of platelet thrombus associated with vessel wall injury and downstream embolization into the microcirculation. METHODS: In eight trials, 5,154 patients were randomized to a regimen comprising conventional therapy plus a bolus of abciximab within 1 h before PCI followed by a 12-h infusion; 4,136 controls were randomized to conventional therapy alone. Patient follow-up from six months to three years was available. Survival differences are examined using proportional hazards regression and survival curves. RESULTS: A hazard ratio of 0.71 (95% confidence interval 0.57 to 0.89; p = 0.003) suggests a mortality benefit with abciximab. The absolute reduction in mortality was estimated to be 0.5% through 30 days, 0.7% through six months, 0.9% through one year and 1.8% through three years. Early MI explained 18% of the observed mortality benefit at one year. Multivariate regression suggests that patients with advanced cardiovascular disease may derive the greatest mortality benefit from abciximab. CONCLUSIONS: The evidence from 9,290 randomized PCI patients shows a mortality benefit provided by abciximab bolus plus 12-h infusion.

Enoxaparin and abciximab adjunctive pharmacotherapy during percutaneous coronary intervention.

Randomized controlled trials of patients with non-ST segment elevation acute coronary syndromes have established the superiority of enoxaparin (versus unfractionated heparin) for reducing adverse ischemic outcomes. Furthermore, adjunctive abciximab therapy during percutaneous coronary intervention (PCI) is associated with improved clinical outcomes. Since algorithms for integrating these pharmacotherapies have not been determined, patients undergoing elective PCI were enrolled into 2 distinct and separate studies conducted by the National Investigators Collaborating on Enoxaparin (NICE) study groups (NICE 1 and NICE 4 studies). Patients in NICE 1 were administered enoxaparin 1.0 mg/kg intravenously (without abciximab) and those enrolled in NICE 4 were administered a reduced dose (0.75 mg/kg) of enoxaparin in combination with standard-dose abciximab intravenously during PCI. Bleeding events and ischemic outcomes assessed in-hospital and at 30-days post-PCI were infrequent with either pharmacologic regimen. In the dose regimens studied, enoxaparin with or without abciximab appears to provide safe and effective anticoagulation during PCI. The combination of reduced-dose enoxaparin and abciximab was associated with a low incidence of adverse outcomes (bleeding or ischemic events). Additional studies may be required to establish the relative safety and efficacy of this new adjunctive pharmacologic strategy when compared with the combination of low-dose, weight-adjusted unfractionated heparin and abciximab.

"Hot" unstable angina--is it worse than subacute unstable angina? Results from the GUARANTEE Registry.

BACKGROUND AND METHODS: Because time to presentation to the hospital affects time to treatment and is known to be important in acute myocardial infarction, we evaluated this variable in patients with unstable angina/non-ST segment elevation myocardial infarction (UA/NSTEMI). Among 2909 consecutive patients with UA/NSTEMI admitted to 35 hospitals in 6 geographic regions of the United States, we compared patients with acute (onset of pain <12 hours before admission) and subacute (onset >12 hours) unstable angina. RESULTS: Patients with "hot" (acute) unstable angina presented more often to the emergency department and were subsequently admitted more often to an intensive care unit. Hospital administration of medications did not differ between the two groups, with the exception of heparin, which was paradoxically used more often in subacute patients (p<0.001). All cardiac invasive procedures were undertaken less often in the acute patients (catheterization, 41.4% vs. 58.7%, p=0.001; percutaneous coronary intervention, 11.3% vs. 21.1%, p=0.001; coronary artery bypass grafting, 5.6% vs. 12.0%, p=0.001). A greater percentage of acute patients were found to have no significant coronary artery disease at cardiac catheterization (20.1% vs. 15.0%, p=0.006). Mortality did not differ between the two groups; however, the composite endpoint of death and MI favored the acute patients (1.3% vs. 2.2%, p=0.032). CONCLUSIONS: Contrary to our initial hypothesis, "hot" UA patients tended to be at lower risk than patients with subacute presentation, highlighting the fact that patients with UA/NSTEMI remain at high risk even after the initial 12-hour period.

Therapeutic potential of GP IIb/IIIa receptor antagonists in acute myocardial infarction.

The management of acute myocardial infarction (AMI) has changed dramatically over the last two decades, with the addition of fibrinolytic agents and primary coronary intervention (PCI). The more recent development of the glycoprotein (GP) IIb/IIIa antagonists, a new class of potent antiplatelet drugs, has the potential to considerably enhance the treatment of AMI patients. A number of recent studies have highlighted the potential incremental benefits with adjunctive IIb/IIIa-targeted therapy. In this review, we will discuss the pathophysiology of myocardial infarction (MI), the physiology and role of platelets in thrombosis and describe the currently available drugs. We will briefly summarise the results of recent clinical trials, discuss some key forthcoming trials and attempt to describe how GP IIb/IIIa antagonists may directly impact the immediate and near future day-to-day care of patients with AMI.

Unstable angina and non-ST-segment elevation myocardial infarction: perspectives on combination therapy.

We reviewed recent clinical data on the management of unstable angina and non-ST segment elevation myocardial infarction. We concentrated on the use of new therapies, particularly in combination with both older agents and other new methods, in order to present health care providers with an overview of available treatment options. The clinical trials reviewed herein provide strong evidence and proof of principle that combination therapies targeting 1) platelet function (aspirin, thienopyridines, and GP IIb/IIIa antagonists), 2) the coagulation cascade (unfractionated heparin and low-molecular-weight heparin), and 3) the physical characteristics of the active lesion (percutaneous intervention) reduce the risk of death or ischemic complications after thrombotic progression of coronary atherosclerosis.

Endoluminal reconstruction of the arterial wall with endothelial cell/glue matrix reduces restenosis in an atherosclerotic rabbit.

OBJECTIVES: The objectives of this study were 1) to improve the attachment of reimplanted endothelial cells (EC) using a fibrin glue, and 2) to assess the impact of endothelial reseeding on restenosis eight weeks after balloon angioplasty. BACKGROUND: A possible mechanism contributing to restenosis after balloon angioplasty is the loss of the EC lining. Previous attempts to reseed EC had little effect due to rapid loss of the seeded cells. METHODS: Twelve atherosclerotic rabbits were subjected to angioplasty of iliac arteries and reseeding procedure. One iliac artery was subjected to EC/glue reconstruction and a contralateral site to EC seeding without glue. The animals were sacrificed after 4 h. In another series 12 rabbits were treated in the same fashion and were restudied at eight weeks. Additionally, in 10 animals one iliac was subjected to glue treatment, and another served as control. RESULTS: Histological examination demonstrated the ability of this method to reattach the EC/glue matrix circumferentially to 68.0 +/- 6.7% of the arterial wall in comparison with 13.5 +/- 3.9% reattachment after EC seeding. Morphometry at eight weeks showed that the lumen area was significantly greater in the EC/glue group (1.23 +/- 0.35 mm2) than in the EC seeding alone (0.65 +/- 0.02 mm2) and 0.72 +/- 0.41 mm2 in the glue group. This was principally accounted for by the statistically significant differences in the intimal area (0.76 +/- 0.18 mm vs. 1.25 +/-0.26 mm2 and 1.01 +/- 0.53 mm2, respectively). CONCLUSIONS: The attachment of EC after angioplasty can be greatly improved with fibrin glue matrix. The near 70% endothelial coverage achieved by this method resulted in a significant reduction of restenosis in atherosclerotic rabbit.

New insights in cardiac structural changes in patients with Fabry's disease.

BACKGROUND: Fabry's disease is an X-linked recessive genetic deficiency of the enzyme alpha-galactosidase leading to the pathologic intracellular deposition of neutral glycosphingolipids. Although cardiac involvement is frequent, there is controversy regarding the character of the associated left ventricular (LV) changes and the severity of valvular involvement. METHODS: Clinical evaluation (disease severity scaling, laboratory tests, and echocardiography) was performed in 13 hemizygous men (mean age 39 +/- 10 years) and 17 heterozygous women (mean age 35 +/- 19 years). RESULTS: LV hypertrophy (LVH) was frequent in subjects older than 30 years, more often in men (61%) than in women (18%, P <.001). The degree of LVH was independently associated with age and the logarithm of alpha-galactosidase activity (r(2) = 0.70, P <.001). The predominant LV geometric patterns were concentric LVH and remodeling, both present in 11 subjects (36%). Three patients had an asymmetric septal hypertrophy mimicking hypertrophic cardiomyopathy. In most subjects with LVH, the systolic function was normal and severe diastolic dysfunction (restrictive pattern) was not noted. Minor structural abnormalities of the mitral valve were found in 17 subjects (57%). The aortic valve was affected in 14 patients (47%). Valvular abnormalities were frequently accompanied by regurgitation of minor to mild degree. The presence of LVH or valvular changes was associated with increased disease severity. CONCLUSIONS: Echocardiographically detectable cardiac involvement is frequent with Fabry's disease, particularly in older subjects, and more pronounced in affected hemizygous men than in heterozygous women. LVH is frequently observed but usually not associated with significant systolic or restrictive diastolic dysfunction. Concentric LVH and remodeling appear to be the major manifestations of LV structural alteration. The frequently noted valvular abnormalities were not associated with a significant degree of regurgitation. Valvular and especially LV structural changes may serve as a useful marker of disease severity.

Combining low-molecular-weight heparin and glycoprotein IIb/IIIa antagonists for the treatment of acute coronary syndromes: the NICE 3 story. National Investigators Collaborating on Enoxaparin.

In recent years, a number of new therapies have become available that have significantly improved the care of patients with acute coronary syndromes (ACS). A number of studies have documented the significant superiority of the low-molecular-weight heparin (LMWH), enoxaparin, over unfractionated heparin (UFH) in the treatment of ACS. However, there are insufficient data regarding the safety of using LMWH in combination with glycoprotein (GP) IIb/IIIa antagonists. The NICE 3 study is an open-labeled, non-randomized, observational study examining the feasibility, safety, and preliminary efficacy of the LMWH, enoxaparin, in combination with each of the three commercially available GP IIb/IIIa antagonists in ACS patients. Approximately 600 patients at 45 clinical centers in North America will be divided between the three arms of the trial, representing each of the three GP IIb/IIIa antagonists. Once therapy is initiated, patients will receive no UFH (unless they require a coronary artery bypass graft) and will continue treatment even if invasive cath lab procedures are necessary. NICE 3 builds on the previous experiences of NICE 1 and NICE 4 with LMWH in the cath lab (with or without GP IIb/IIIa antagonists) to more aggressively extend the use of LMWHs into the medical management of ACS patients.