Elliott M. Antman

Bio: Elliott M. Antman is an academic researcher from Brigham and Women's Hospital. The author has contributed to research in topics: Myocardial infarction & TIMI. The author has an hindex of 161, co-authored 716 publications receiving 179462 citations. Previous affiliations of Elliott M. Antman include Duke University & Katholieke Universiteit Leuven.

Low-Molecular-Weight Heparins An Intriguing New Twist With Profound Implications

Abstract: Modern antithrombotic therapy for acute coronary syndromes rests on a growing body of basic and clinical evidence that rupture or erosion of the surface of a vulnerable plaque sets in motion a sequence of events culminating in thrombus formation in the culprit vessel.1 When the contents of a vulnerable plaque are exposed to the bloodstream, platelets adhere to the subendothelial matrix, release ADP and thromboxane A2, and amplify the generation of thrombin.2 As a result, a platelet aggregate begins to develop. In addition, the coagulation cascade is activated and fibrin strands are formed. Thrombin (factor IIa) plays a pivotal role in the processes described above because of its extensive procoagulant and prothrombotic actions.3 In addition to catalyzing the transformation of soluble fibrinogen into fibrin monomers and activating factor XIII to produce cross-linked fibrin, thrombin promotes clot formation by activating factors V and VIII. It is also one of the most potent agents responsible for platelet adhesion, activation, and aggregation. In vessels with a diseased endothelium, thrombin promotes the release of the vasoconstrictor endothelin 1. Importantly, thrombin also potentiates the proliferative effects of multiple growth factors and is a key mediator of early smooth muscle cell proliferation after arterial injury. There is now abundant evidence that thrombus formation can be prevented by direct or indirect inactivation of thrombin or by inhibition of thrombin production via the intrinsic or extrinsic limbs of the coagulation pathway.3 Unfractionated heparin, the standard antithrombotic agent in clinical practice, is a glycosaminoglycan, consisting of chains of alternating residues of d-glucosamine and uronic acid.4 Although familiar to the vast majority of clinicians, unfractionated heparin has several disadvantages: (1) a variable anticoagulant effect (necessitating frequent monitoring of activated partial thromboplastin time), (2) neutralization by platelet factor 4, (3) less effective inhibition …

Outcomes and Optimal Antithrombotic Therapy in Women Undergoing Fibrinolysis for ST-Elevation Myocardial Infarction

Abstract: Background— The manifestations, complications, and outcomes of cardiovascular disease differ between women and men. The safety and efficacy of pharmacological reperfusion therapy in women with ST-elevation myocardial infarction are of particular interest. Methods and Results— We investigated outcomes in the Enoxaparin and Thrombolysis Reperfusion for Acute Myocardial Infarction Treatment–Thrombolysis in Myocardial Infarction (ExTRACT-TIMI) 25 study, which randomized ST-elevation myocardial infarction patients with planned fibrinolysis to enoxaparin or unfractionated heparin. Compared with men (n=15 696), women (n=4783) were older and more likely to have hypertension and diabetes (P 2-fold higher than for men (13.2% versus 5.4%; odds ratio, 2.66; 95% CI, 2.40 to 2.96). After adjustment for age, fibrinolytic therapy, revascularization, region, and elements of the TIMI Risk Score, women had a 1.25-fold-higher 30-day risk of death (95% CI, 1.08 to 1....

Distance from the coronary ostium to the culprit lesion in acute ST-elevation myocardial infarction and its implications regarding the potential prevention of proximal plaque rupture

Abstract: Background: Shorter distances from the coronary ostia to culprit lesions have been associated with a higher incidence of adverse outcomes in ST elevation acute myocardial infarction (STEMI). As drug-eluting stents are associated with low rates of restenosis and formation of a stable intima, we sought to develop a mathematical model to estimate how far down the coronary artery a drug-eluting stent would have to be placed to theoretically mitigate the risk of proximal plaque rupture.

Predictors of the rise in vWF after ST elevation myocardial infarction: implications for treatment strategies and clinical outcome: An ENTIRE-TIMI 23 substudy.

Abstract: Aims Prior studies suggest that acute coronary syndromes (ACSs) are associated with endothelial activation and that this is of prognostic significance. We hypothesized that endothelial activation, as measured by a rise in von Willebrand Factor (ΔvWF), was influenced by the thrombolysis in myocardial infarction flow grade (TFG), the corrected TIMI frame count (CTFC) and the choice of anticoagulant therapy after fibrinolysis in ST elevation myocardial infarction (STEMI). Methods and results Data were drawn from the enoxaparin and tenecteplase tissue plasminogen activator (TNK-tpa) with or without GPIIb/IIIa inhibitor as the reperfusion strategy in the STEMI trial (ENTIRE-TIMI 23). Three hundred and fourteen patients had serial measurements of vWF (baseline and 48–72 h) and angiographic data available. TFG<3 ( P =0.0042) or CTFC≥40 at 60 min ( P =0.0035) were associated with a higher ΔvWF. ΔvWF ≥75th percentile was associated with a higher incidence of death or myocardial infarction (MI) at 30 days, compared with <75th percentile (11.2 vs. 4.1%, P =0.027). Enoxaparin independently reduced the ΔvWF ( P =0.019) and also the composite of death or MI (OR 0.33, 95% CI 0.12–0.91, P =0.03) compared with unfractionated heparin. Conclusion In STEMI treated by fibrinolysis, coronary flow at 60 min and choice of adjunctive anticoagulant appear to be independent determinants of ΔvWF. Enoxaparin is independently associated with a reduction in ΔvWF and a reduction in death or MI. The clinical benefits of enoxaparin as an adjunctive treatment in STEMI may be mediated in part by a reduction in vWF release.

Measuring inconsistency in meta-analyses

Abstract: Cochrane Reviews have recently started including the quantity I 2 to help readers assess the consistency of the results of studies in meta-analyses. What does this new quantity mean, and why is assessment of heterogeneity so important to clinical practice? Systematic reviews and meta-analyses can provide convincing and reliable evidence relevant to many aspects of medicine and health care.1 Their value is especially clear when the results of the studies they include show clinically important effects of similar magnitude. However, the conclusions are less clear when the included studies have differing results. In an attempt to establish whether studies are consistent, reports of meta-analyses commonly present a statistical test of heterogeneity. The test seeks to determine whether there are genuine differences underlying the results of the studies (heterogeneity), or whether the variation in findings is compatible with chance alone (homogeneity). However, the test is susceptible to the number of trials included in the meta-analysis. We have developed a new quantity, I 2, which we believe gives a better measure of the consistency between trials in a meta-analysis. Assessment of the consistency of effects across studies is an essential part of meta-analysis. Unless we know how consistent the results of studies are, we cannot determine the generalisability of the findings of the meta-analysis. Indeed, several hierarchical systems for grading evidence state that the results of studies must be consistent or homogeneous to obtain the highest grading.2–4 Tests for heterogeneity are commonly used to decide on methods for combining studies and for concluding consistency or inconsistency of findings.5 6 But what does the test achieve in practice, and how should the resulting P values be interpreted? A test for heterogeneity examines the null hypothesis that all studies are evaluating the same effect. The usual test statistic …

The PRISMA Statement for Reporting Systematic Reviews and Meta-Analyses of Studies That Evaluate Health Care Interventions: Explanation and Elaboration

Abstract: Systematic reviews and meta-analyses are essential to summarize evidence relating to efficacy and safety of health care interventions accurately and reliably. The clarity and transparency of these reports, however, is not optimal. Poor reporting of systematic reviews diminishes their value to clinicians, policy makers, and other users. Since the development of the QUOROM (QUality Of Reporting Of Meta-analysis) Statement—a reporting guideline published in 1999—there have been several conceptual, methodological, and practical advances regarding the conduct and reporting of systematic reviews and meta-analyses. Also, reviews of published systematic reviews have found that key information about these studies is often poorly reported. Realizing these issues, an international group that included experienced authors and methodologists developed PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) as an evolution of the original QUOROM guideline for systematic reviews and meta-analyses of evaluations of health care interventions. The PRISMA Statement consists of a 27-item checklist and a four-phase flow diagram. The checklist includes items deemed essential for transparent reporting of a systematic review. In this Explanation and Elaboration document, we explain the meaning and rationale for each checklist item. For each item, we include an example of good reporting and, where possible, references to relevant empirical studies and methodological literature. The PRISMA Statement, this document, and the associated Web site (http://www.prisma-statement.org/) should be helpful resources to improve reporting of systematic reviews and meta-analyses.

The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report.

Abstract: "The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure" provides a new guideline for hypertension prevention and management. The following are the key messages(1) In persons older than 50 years, systolic blood pressure (BP) of more than 140 mm Hg is a much more important cardiovascular disease (CVD) risk factor than diastolic BP; (2) The risk of CVD, beginning at 115/75 mm Hg, doubles with each increment of 20/10 mm Hg; individuals who are normotensive at 55 years of age have a 90% lifetime risk for developing hypertension; (3) Individuals with a systolic BP of 120 to 139 mm Hg or a diastolic BP of 80 to 89 mm Hg should be considered as prehypertensive and require health-promoting lifestyle modifications to prevent CVD; (4) Thiazide-type diuretics should be used in drug treatment for most patients with uncomplicated hypertension, either alone or combined with drugs from other classes. Certain high-risk conditions are compelling indications for the initial use of other antihypertensive drug classes (angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, β-blockers, calcium channel blockers); (5) Most patients with hypertension will require 2 or more antihypertensive medications to achieve goal BP (<140/90 mm Hg, or <130/80 mm Hg for patients with diabetes or chronic kidney disease); (6) If BP is more than 20/10 mm Hg above goal BP, consideration should be given to initiating therapy with 2 agents, 1 of which usually should be a thiazide-type diuretic; and (7) The most effective therapy prescribed by the most careful clinician will control hypertension only if patients are motivated. Motivation improves when patients have positive experiences with and trust in the clinician. Empathy builds trust and is a potent motivator. Finally, in presenting these guidelines, the committee recognizes that the responsible physician's judgment remains paramount.

Cochrane Handbook for Systematic Reviews of Interventions

Abstract: The Cochrane Handbook for Systematic Reviews of Interventions is the official document that describes in detail the process of preparing and maintaining Cochrane systematic reviews on the effects of healthcare interventions.