Coronary artery bypass surgery in patients with acute coronary syndromes is difficult to predict

Meta-Analysis of Nonrandomized Studies to Assess the Optimal Timing of Coronary Artery Bypass Grafting After Acute Myocardial Infarction

The optimal timing of coronary artery bypass grafting (CABG) in patients after an acute myocardial infarction (MI) is unknown. We performed a systematic review and meta-analysis of studies comparing mortality rates in patients who underwent CABG at different time intervals after acute MI. Bias assessments were completed for each study, and summary of proportions of all-cause mortality were calculated based on CABG at various time intervals after MI. A total of 22 retrospective studies, which included a total of 137,373 patients were identified. The average proportion of patients who died when CABG was performed within 6 hours of MI was 12.7%, within 6 to 24 hours of MI was 10.9%, within 1 day of MI was 9.8%, any time after 1 day of MI was 3.0%, within 7 days of MI was 5.9%, and any time after 7 days of MI was 2.7%. Interstudy heterogeneity, assessed using I² values, showed significant heterogeneity in death rates within subgroups. Only 1 study accounted for immortal time bias, and there was a serious risk of selection bias in all other studies. Confounding was found to be a serious risk for bias in 55% of studies because of a lack of accounting for type of MI, MI severity, or other verified cardiac risk factors. The current publications comparing timing of CABG after MI is at serious risk of bias because of patient selection and confounding, with heterogeneity in both study populations and intervention time intervals.

The Pharmacological Approach to Oncologic Patients with Acute Coronary Syndrome

Among acute coronary syndrome (ACS) patients, 15% have concomitant cancer, especially in the first 6 months after their diagnosis, as well as in advanced metastatic stages. Lung, gastric, and pancreatic cancers are the most frequent malignancies associated with ACS. Chemotherapy and radiotherapy exert prothrombotic, vasospastic, and proinflammatory actions. The management of cancer patients with ACS is quite challenging: percutaneous revascularization is often underused, and antiplatelet and anticoagulant pharmacological therapy should be individually tailored to the thrombotic risk and to the bleeding complications. Sometimes oncological patients also show different degrees of thrombocytopenia, which further complicates the pharmacological strategies. The aim of this review is to summarize the current evidence regarding the treatment of ACS in cancer patients and to suggest the optimal management and therapy to reduce the risk of adverse coronary events after ACS in this high-risk population.

ED administration of thienopyridines in non-ST-segment elevation myocardial infarction: results from the NCDR

OBJECTIVE

American Heart Association/American College of Cardiology guidelines recommend that patients with definite unstable angina or non-ST-segment elevation myocardial infarction (NSTEMI) receive dual antiplatelet therapy on presentation to the hospital when undergoing early invasive management or "as soon as possible" after admission when being managed conservatively. The guidelines do not specify whether these medications should be administered in the emergency department (ED). Our aim was to determine whether ED administration of a thienopyridine was associated with clinical outcomes among patients with NSTEMI.

METHODS

We examined thienopyridine use in 39454 patients with NSTEMI who received a thienopyridine within 24 hours of presentation in the National Cardiovascular Data Registry's Acute Coronary Treatment and Intervention Outcomes Network-Get With The Guidelines Registry from January 2007 to June 2010. Patients who were not seen initially in the ED, were transferred in, or were missing time data were excluded. We analyzed the association between ED administration of thienopyridines and outcomes and patient demographics.

RESULTS

Of the cohort receiving a thienopyridine within 24 hours, 9534 (24.2%) received it in the ED. Emergency department administration of a thienopyridine was not associated with in-hospital major bleeding (multivariable adjusted odds ratio, 0.99; 95% confidence interval, 0.91-1.09) or in-hospital mortality (adjusted 1.02; 95% confidence interval, 0.86-1.20). Independent predictors most strongly associated with ED thienopyridine administration were elevated troponin, ED length of stay, prior percutaneous coronary intervention, and initial electrocardiogram showing ischemic changes.

CONCLUSIONS

There was no association between ED thienopyridine administration and in-hospital major bleeding or mortality. Emergency department length of stay, electrocardiographic changes, and elevated troponin were associated with ED thienopyridine administration.

Acute coronary syndromes: considerations for improved acceptance and implementation of management guidelines

The management of acute coronary syndrome in Europe is covered by various European Society of Cardiology guidelines, which although valuable, are complex and may not always provide clear guidance in everyday clinical practice. Consequently, implementation of the guideline recommendations is frequently suboptimal. To complicate matters further, a wealth of new data from large trials examining novel anti-thrombotic agents will become or are already available, necessitating guideline updates. This article summarizes the gaps between current guideline-recommended treatment of acute coronary syndrome and daily practice as dictated by the evidence base, including recent trials. Reasons for the suboptimal implementation of the current European Society of Cardiology guidelines and possible solutions to making these more practice oriented are presented.

Early clopidogrel use in non-ST elevation acute coronary syndrome and subsequent coronary artery bypass grafting

Clopidogrel use is associated with a significant decrease in major adverse cardiac events when used in patients with non-ST elevation acute coronary syndromes (NSTE-ACS), and guidelines give a class I level of evidence A recommendation for the use of clopidogrel in these patients. The optimal timing of clopidogrel use has not been conclusively determined, but nearly all data available support early use in patients with NSTE-ACS. Despite this, clopidogrel usage is far less than expected based on current guidelines because of concern for bleeding at the time of possible subsequent coronary artery bypass grafting (CABG). Clopidogrel use has been associated with increased perioperative bleeding at the time of CABG, but data are mixed. Numerous studies have conclusively shown that this bleeding risk is confined to those patients receiving clopidogrel within 5 days of CABG. The absolute number of patients exposed to this possible bleeding risk is very small relative to the >1 million patients who present annually with NSTE-ACS and is estimated to be <0.8% of these patients. Recent data have shown that (1) holding clopidogrel for 5 days before CABG is safe in patients with NSTE-ACS and (2) clopidogrel use in patients with NSTE-ACS decreases ischemic events in patients referred for CABG compared to patients who are not given clopidogrel. These data strongly challenge the notion that clopidogrel should be withheld until it is determined if the patient will be referred for CABG.

Emergency cardiac surgery in patients with acute coronary syndromes: a review of the evidence and perioperative implications of medical and mechanical therapeutics

Patients with acute coronary syndromes who require emergency cardiac surgery present complex management challenges. The early administration of antiplatelet and antithrombotic drugs has improved overall survival for patients with acute myocardial infarction, but to achieve maximal benefit, these drugs are given before coronary anatomy is known and before the decision to perform percutaneous coronary interventions or surgical revascularization has been made. A major bleeding event secondary to these drugs is associated with a high rate of death in medically treated patients with acute coronary syndrome possibly because of subsequent withholding of antiplatelet and antithrombotic therapies that otherwise reduce the rate of death, stroke, or recurrent myocardial infarction. Whether the added risk of bleeding and blood transfusion in cardiac surgical patients receiving such potent antiplatelet or antithrombotic therapy before surgery specifically for acute coronary syndromes affects long-term mortality has not been clearly established. For patients who do proceed to surgery, strategies to minimize bleeding include stopping the anticoagulation therapy and considering platelet and/or coagulation factor transfusion and possibly recombinant-activated factor VIIa administration for refractory bleeding. Mechanical hemodynamic support has emerged as an important option for patients with acute coronary syndromes in cardiogenic shock. For these patients, perioperative considerations include maintaining appropriate anticoagulation, ensuring suitable device flow, and periodically verifying correct device placement. Data supporting the use of these devices are derived from small trials that did not address long-term postoperative outcomes. Future directions of research will seek to optimize the balance between reducing myocardial ischemic risk with antiplatelet and antithrombotics versus the higher rate perioperative bleeding by better risk stratifying surgical candidates and by assessing the effectiveness of newer reversible drugs. The effects of mechanical hemodynamic support on long-term patient outcomes need more stringent analysis.

An early and simple predictor of severe left main and/or three-vessel disease in patients with non-ST-segment elevation acute coronary syndrome

Clopidogrel should be initiated as soon as possible in patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS) except those who urgently require coronary artery bypass grafting (CABG). The present study assessed the ability to predict severe left main coronary artery and/or 3-vessel disease (LM/3VD) that would most likely require urgent CABG based on only clinical factors on admission in 572 patients with NSTE-ACS undergoing coronary angiography. Severe LM/3VD was defined as ≥75% stenosis of LM and/or 3VD with ≥90% stenosis in ≥2 proximal lesions of the left anterior descending coronary artery and other major epicardial arteries. Patients were divided into the 3 groups according to angiographic findings: no LM/3VD (n = 460), LM/3VD but not severe LM/3VD (n = 57), and severe LM/3VD (n = 55). Severe LM/3VD was associated with a higher rate of urgent CABG compared to no LM/3VD and LM/3VD but not severe LM/3VD (46%, 2%, and 2%, p <0.001). On multivariate analysis, degree of ST-segment elevation in lead aVR was the strongest predictor of severe LM/3VD (odds ratio 29.1, p <0.001), followed by positive troponin T level (odds ratio 1.27, p = 0.044). ST-segment elevation ≥1.0 mm in lead aVR best identified severe LM/3VD with 80% sensitivity, 93% specificity, 56% positive predictive value, and 98% negative predictive value. In conclusion, ST-segment elevation ≥1.0 mm in lead aVR on admission electrocardiogram is highly suggestive of severe LM/3VD in patients with NSTE-ACS. Selected patients with this finding might benefit from promptly undergoing angiography, withholding clopidogrel to allow early CABG.

Underutilization of clopidogrel and glycoprotein IIb/IIIa inhibitors in non-ST-elevation acute coronary syndrome patients: the Canadian global registry of acute coronary events (GRACE) experience

BACKGROUND

There are limited contemporary data on the early use of clopidogrel or glycoprotein (Gp) IIb/IIIa inhibitors, alone versus combination therapies, in non-ST-elevation acute coronary syndrome (NSTE-ACS).

METHODS

This study included 5,806 Canadian NSTE-ACS patients with elevated cardiac biomarker and/or ST deviation on presentation in the prospective GRACE between 2003-2007. We stratified the study population according to the management strategy (non-invasive vs invasive) and into low-(GRACE risk score <or=108), intermediate- (109-140), and high-risk groups (>or=141).

RESULTS

Overall, 3,893 patients (67.1%) received early (<or=24 hours of admission) antiplatelet therapy; the rates of use were 76%, 73%, and 57% in the low-, intermediate-, and high-risk groups, respectively (P for trend < .001). Only 54% of the conservatively managed patients and 12% of the invasively managed patients received early clopidogrel and GpIIb/IIIa inhibitors, respectively. High-risk patients were less likely (adjusted odds ratio = 0.48, 95% CI 0.39-0.59, P < .001) to receive early clopidogrel or GpIIb/IIIa inhibitors, whereas in-hospital catheterization was an independent positive predictor (adjusted odds ratio = 2.02, 95% CI 1.74-2.34, P < .001) of use.

CONCLUSIONS

In this contemporary NSTE-ACS population, both clopidogrel and GpIIb/IIIa inhibitors were targeted toward patients treated with an invasive strategy but paradoxically toward the lower-risk group. In particular, clopidogrel appeared to be underused among conservatively managed patients despite its proven efficacy, whereas GpIIb/IIIa inhibitors were administered to only a minority of the high-risk patients with elevated cardiac biomarkers. Our findings emphasize the ongoing need to promote the optimal use of evidence-based antiplatelet therapies among high-risk patients with NSTE-ACS.

Oral antiplatelet therapy in unstable angina/non-ST-segment elevation myocardial infarction, ST-segment elevation myocardial infarction, and percutaneous coronary intervention: is it time for a guideline update?

Oral antiplatelet drugs are central in the management of acute coronary syndromes, including unstable angina/non-ST-segment elevation myocardial infarction, ST-segment elevation myocardial infarction, and percutaneous coronary intervention. However, the mechanisms that confer the benefits of these agents also increase bleeding risk. Thus, the selection of appropriate pharmacotherapy requires close attention to the delicate balance between reducing the risk of ischemic events and minimizing bleeding risk. A critical review of the 2007 guidelines in these areas and new clinical data with currently available and soon-to-be-approved antiplatelet agents are presented.

Temporal trends and patterns of early clopidogrel use across the spectrum of acute coronary syndromes

BACKGROUND

Randomized trials have established efficacy of clopidogrel in various types of acute coronary syndromes (ACS). The objective of this study was to examine the temporal trends and patterns of early clopidogrel use (within the first 24 hours of hospitalization) across the spectrum of patients with ACS in Canada.

METHODS

Using the multinational, prospective GRACE (Global Registry of Acute Coronary Events) and GRACE(2), we identified 11,177 patients who were admitted for ACS from January 2003 to December 2007 in Canada. Demographic information, clinical features, and treatment were recorded. We examined the early use of clopidogrel over time and in relation to the type of ACS, clinical features on presentation, and the mode of reperfusion therapy.

RESULTS

Of the 11,177 patients with ACS, 3,091 (27.7%) had ST-elevation myocardial infarction (STEMI), 5,194 (46.5%) had non-STEMI, and 2,892 (25.9%) had unstable angina; the rates of early clopidogrel administration were 63.0%, 66.6%, and 57.2%, respectively (P < .001). Overall, there was a significant increase in clopidogrel use over the period studied (P for trend < .001). In patients with non-ST-elevation ACS (non-STEMI and unstable angina), clopidogrel use was higher among those with positive cardiac biomarkers compared to those without (67.1% vs 59.8%, P < .001) but similar in the groups with and without ST deviation. There was an inverse relationship between GRACE risk score and rates of early clopidogrel administration. In patients with STEMI receiving fibrinolytic therapy, only 55.7% of patients <65 years old received clopidogrel compared with 47.0% and 42.6% of patients 65 to 74 and >75 years old, respectively (P for trend < .001).

CONCLUSIONS

Although early use of clopidogrel therapy has increased over time across the spectrum of ACS, a significant proportion of eligible patients still do not receive this evidence-based therapy. There is a need to optimize the use of proven antiplatelet therapies to improve clinical outcome.