A randomized factorial trial of reperfusion strategies and aspirin dosing in acute myocardial infarction. The DUCCS-II Investigators

The recanalization after thrombolysis as surrogate for clinical outcomes in patients with ST-segment elevation acute myocardial infarction: A systematic review and meta-regression analysis of data from randomized controlled trials

AIMS

Thrombolytic therapy has been known to be effective in reducing clinical outcomes and increasing recanalization rate among patients with ST-segment elevation acute myocardial infarction (STEMI). However, whether post-thrombolysis recanalization could be used as a surrogate for clinical outcomes is unknown.

METHODS

We systematically searched PubMed, EMBASE and the Cochrane Library database to identify randomized controlled trials (RCT) that examined effects of thrombolytic agents in STEMI. Recanalization was defined as TIMI grade 2 or 3 flow. The primary outcome was in-hospital all-cause mortality. Secondary outcomes included in-hospital and 30-day recurrent myocardial infarction (re-MI), composite of death and re-MI, major bleeding and all bleeding. Random-effects meta-regression was used for analysis.

RESULTS

We identified 111 eligible study arms and 52 eligible comparisons from 58 RCTs involving 16 536 patients. Our analyses showed that among study arms recanalization rate was significantly inversely associated with the incidence of in-hospital all-cause mortality (β: -0.07, 95% confidence interval [CI]: -0.13 to -0.02), re-MI (β: -0.09, 95%CI: -0.18 to -0.01) and the composite of death and re-MI (β: -0.17, 95%CI: -0.28 to -0.05), and positively associated with in-hospital all bleeding but not with major bleeding. Among paired comparisons, the difference in recanalization rate was associated with the corresponding difference in incidence of in-hospital all-cause mortality (β: -0.15, 95%CI: -0.28 to -0.01) but the relationship was not significant for any other outcome.

CONCLUSION

Pooled evidence from RCTs suggest the potential use of recanalization as a surrogate for clinical outcomes in evaluating the efficacy of thrombolysis among patients with STEMI.

Optimal aspirin dose in acute coronary syndromes: an emerging consensus

ABSTRACT: 

Numerous clinical trials testing the efficacy of aspirin for the secondary prevention of cardiovascular disease have been published. We reviewed the literature pertaining to aspirin dose in acute coronary syndrome patients. Clinical trials assessing the comparative efficacy of different doses of aspirin are scarce. This complex antiplatelet therapy landscape makes it difficult to identify the best aspirin dose for optimizing efficacy and minimizing risk of adverse events, while complying with the various guidelines and recommendations. Despite this fact, current evidence suggests that aspirin doses of 75–100 mg/day may offer the optimal benefit:risk ratio in acute coronary syndrome patients.

Relation between aspirin dose, all-cause mortality, and bleeding in patients with recent cerebrovascular or coronary ischemic events (from the BRAVO Trial)

Despite aspirin's established role in the treatment of atherosclerotic vascular disease, considerable controversy exists regarding its most effective dosing strategy. In a retrospective observational study, we examined the relation between prescribed aspirin dose (<162 mg vs > or =162 mg/day aspirin) and clinical outcome in 4,589 placebo-treated patients enrolled in the Blockage of the Glycoprotein IIb/IIIa Receptor to Avoid Vascular Occlusion (BRAVO) trial over a median follow-up of 366 days. Standard Cox regression analysis was employed because propensity analysis was not feasible. Compared with lower aspirin doses, higher doses were associated with lower unadjusted all-cause mortality (2.9 vs 1.6%, respectively; log rank chi-square 8.6, p = 0.0034). Higher aspirin dose remained independently predictive of lower all-cause mortality in a multivariable Cox proportional hazards model (hazard ratio 0.64, 95% confidence interval 0.42 to 0.97, p = 0.037). However, there was no significant difference in the incidence of the composite endpoint death, nonfatal myocardial infarction, or nonfatal stroke (6.1% vs 6.2%, p = 0.74). Higher aspirin dose was a significant independent predictor of any (hazard ratio 1.32, 95% confidence interval 1.12 to 1.55, p = 0.001) but not serious bleeding. In conclusion, our findings suggest that aspirin doses of > or =162 mg/day may be more beneficial than those <162 mg/day at preventing death.

Initial Aspirin Dose and Outcome Among ST-Elevation Myocardial Infarction Patients Treated With Fibrinolytic Therapy

Background— Although treatment with immediate aspirin reduces morbidity and mortality in ST-elevation myocardial infarction, the optimal dose is unclear. We therefore compared the acute mortality and bleeding risks associated with the initial use of 162 versus 325 mg aspirin in fibrinolytic-treated ST-elevation myocardial infarction patients.

Methods and Results— Using combined data from the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO I) and Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO III) trials (n=48 422 ST-elevation myocardial infarction patients), we compared the association between initial aspirin dose of 162 versus 325 mg and 24-hour and 7-day mortality, as well as rates of in-hospital moderate/severe bleeding. Results were adjusted for previously identified mortality and bleeding risk factors. Overall, 24.4% of patients (n=11 828) received an initial aspirin dose of 325 mg, and 75.6% (n=36 594) received 162 mg. The 24-hour mortality rates were 2.9% versus 2.8% ( P =0.894) for those receiving an initial aspirin dose of 325 versus 162 mg. Mortality rates at 7 and 30 days were 5.2% versus 4.9% ( P =0.118) and 7.1% versus 6.5% ( P =0.017) among patients receiving the 325 versus 162 mg aspirin. After adjustment, aspirin dose was not associated with 24-hour (odds ratio [OR], 1.01; 95% CI, 0.82 to 1.25), 7-day (OR, 1.00; 95% CI, 0.87 to 1.17), or 30-day (OR, 0.99; 95% CI, 0.87 to 1.12) mortality rates. No significant difference was noted for myocardial infarction or the composite of death or myocardial infarction between groups. In-hospital moderate/severe bleeding occurred in 9.3% of those treated with 325 mg versus 12.2% among those receiving 162 mg ( P <0.001). After adjustment, 325 mg was associated with a significant increase in moderate/severe bleeding (OR, 1.14; 95% CI, 1.05 to 1.24; P =0.003).

Conclusion— These data suggest that an initial dose of 162 mg aspirin may be as effective as and perhaps safer than 325 mg for the acute treatment of ST-elevation myocardial infarction.

A cooperative network of trained sites for the conduct of a complex clinical trial: a new concept in multicenter clinical research

BACKGROUND

The purpose of this report is to present a model of physicians in full-time clinical practice participating as investigators in multicenter clinical trials, sponsored by a pharmaceutical or medical device company.

METHODS

This gas-exchange substudy was conducted as a pilot study to establish the feasibility of the 10-member EXERcise testing group of the Duke University Cooperative Cardiovascular Society (EXERDUCCS) consortium to perform a complex multicenter trial using cardiopulmonary exercise testing. An active interchange of information was established involving the principal investigator for the substudy, a dedicated full-time project coordinator, a medical director of the overall EXERDUCCS network site, the project coordinator for the sponsor, and all the participating EXERDUCCS investigators and coordinators.

RESULTS

The sponsor set as a goal of enrollment of 6 subjects per site, and 8 of the 10 sites met this goal. As a result of the successful enrollment and completion of the study and substudy by the EXERDUCCS sites, the sponsor subsequently increased the payment stipends to the sites to compensate for the extra work and expense incurred.

CONCLUSIONS

This cooperative experience accomplished several goals: (1) it allowed a complex clinical trial to be successfully completed in a time frame which would not have been possible using only single unconnected sites; (2) it educated the physician-investigators (and their personnel) in exercise cardiopulmonary; and (3) it prepared the sites for future clinical trials involving this methodology.

Aspirin in cardiovascular disorders. What is the optimum dose?

Clinical trials of aspirin (acetylsalicylic acid) for cardiovascular disorders have employed doses defined for other pharmacological effects of the drug (such as analgesic effects). Antioxidant and anti-inflammatory mechanisms with different dose-response relationships may contribute to the clinical effect of aspirin in cardiovascular disease. The optimal aspirin dose remains uncertain. Although the difference between 325 mg/day and 81 mg/day of aspirin sounds trivial, finding an optimal aspirin dose has enormous potential to reduce ischemic events. Large aspirin doses have not been associated with proportionally greater benefit. For patients with ischemic heart disease, overall consensus defines a range between 75 and 160 mg/day for the secondary prevention of myocardial infarction, stroke, and vascular death. Any benefit of aspirin must be measured against its adverse effects, principally gastrointestinal hemorrhage. The potential for adverse bleeding events may be lower with a 81mg dose, while maintaining clinical benefit. Although current aggregate data is reassuring about aspirin administration, it is increasingly clear that existing aspirin studies are insufficient to conclusively determine an optimal aspirin dose. Platelets can be activated by pathways that are not blocked by aspirin, and the dose of aspirin needed to fully suppress platelet aggregation may be higher in some patients as a result. Higher doses of aspirin than are currently used (75-325 mg/day) may be required in these patients to achieve desired antithrombotic effects. Better understanding of aspirin-resistant populations will facilitate identification of patients who require higher aspirin doses or alternative forms of antiplatelet therapy.

Combining baseline clinical descriptors and real-time response to therapy: the incremental prognostic value of continuous ST-segment monitoring in acute myocardial infarction

BACKGROUND

Clinical descriptors and ST-segment recovery variables hold prognostic information for clinical outcome after thrombolysis for acute myocardial infarction (MI). We sought to define the incremental prognostic value of continuous 12-lead ST-segment monitoring variables to clinical risk descriptors identified by the Global Utilization of Streptokinase and TPA (alteplase) for Occluded Coronary Arteries (GUSTO-I) trial 30-day mortality analysis.

METHODS

Of 1,777 patients enrolled in continuous ST-segment substudies from the Thrombolysis and Angioplasty in Myocardial Infarction (TAMI-9), GUSTO-I, Duke University Clinical Cardiology Study (DUCCS-II), Integrilin to manage Platelet Aggregation to Combat Thrombus in Acute Myocardial Infarction (IMPACT-AMI), Promotion of Reperfusion by Inhibition of Thrombin During Myocardial Infarction Evolution (PRIME), and Platelet Aggregation Receptor Antagonist Dose Investigation and Reperfusion Gain in Myocardial Infarction (PARADIGM) trials, 825 patients qualified for assessment of time to recovery. ST recovery variables analyzed were time to stable ST-recovery and late ST elevation. Patients who were at low clinical risk (n = 261) had no high-risk descriptors, and patients at high clinical risk (n = 564) had at least 1 of these high-risk descriptors: age >or=70 years, systolic blood pressure <or=110 mm Hg, heart rate >or=90 beats/min, anterior MI, or previous MI. High (n = 90), moderate (n = 318), and low (n =417) ST-risk groups were defined by the presence of both slow ST recovery and late ST elevation, one or the other, or neither, respectively. End points analyzed were inhospital death and combined death, reinfarction, or congestive heart failure.

RESULTS

There was a trend toward increased mortality rate in the high-clinical/high-ST-risk group. For the composite end point, ST subgrouping resulted in significant event stratification in both patients at low and high clinical risk. In multivariable analysis, age and heart rate were independent predictors of both mortality and the composite end point. Late ST elevation added incremental prognostic information.

CONCLUSION

Age, heart rate, and late ST elevation are powerful, independent predictors of adverse clinical outcome. Continuous monitoring allows noninvasive assessment of the response to therapy. Consequently, this technique will enhance the potential to risk-stratify individual patients in a real-time setting.

Aspirin dose and six-month outcome after an acute coronary syndrome

OBJECTIVES

This study was designed to compare the efficacy of low and intermediate aspirin doses in acute coronary syndromes.

BACKGROUND

Little is known of the comparative efficacy of low and intermediate aspirin doses in this setting.

METHODS

We compared six-month death, myocardial infarction (MI), and stroke in patients with unstable angina or acute MI discharged while receiving low (<150 mg) or intermediate (> or =150 mg) aspirin therapy in the GUSTO IIb and PURSUIT trials (n = 20,521). We used multivariable analysis and performed a propensity analysis in order to adjust for baseline imbalances between the groups.

RESULTS

Aspirin doses <150 mg were prescribed to 29.9% (6,128) of patients. By six months, 6.4% of the patients (1,310 of 20,521) had a primary event, 6.2% of the patients receiving <150 mg and 6.6% of the patients receiving aspirin doses > or =150 mg (hazard ratio [HR] 1.06 [95% confidence interval (CI) 0.94 to 1.19], p = 0.35). After adjusting for baseline imbalances and the propensity score for discharge aspirin dose, there was no effect of aspirin dose on the composite end point at six months (HR 0.92 [95% CI 0.79 to 1.07], p = 0.28). However, the higher aspirin dose was associated with a reduction in six-month MI (HR 0.79 [95% CI 0.64 to 0.98], p = 0.03). The outcome was similar when patients were matched on the basis of the propensity score for aspirin dose (HR for death/MI/stroke 0.94 [95% CI 0.80 to 1.12], p = 0.51), although stroke occurred significantly more frequently among patients receiving the higher aspirin dose (HR 1.74 [95% CI 1.01 to 3.02] p = 0.05) and the effect on MI was no longer apparent.

CONCLUSIONS

Although these data are non-randomized, they suggest that the aspirin dose upon discharge may influence the clinical course after unstable angina or acute MI.

[Practice guidelines of the Spanish Society of Cardiology. Recommendations for the use of antithrombotic treatment in cardiology]

The indications for the use of antithrombotic therapy are evolving as new drugs become available or new indications or dosages are recommended for drugs already in use. This document reviews and updates the former one published in 1994. To that end, an exhaustive revision of the literature published in the last 15 years has been undertaken. Following the evidence based medicine dictates, and aiming to select all the relevant publications for each pathology, all studies were selected through MEDLINE, using the specified key words for each subject, and were filtered using the following steps: a) only randomized, controlled studies, meta-analysis, guidelines and review articles were chosen; b) then, the Best-Evidence and Cochrane Collaboration databases were consulted; c) finally, the evidence based medicine validation, relevance and applicability criteria were assessed for each publication. The use of antiaggregants and anticoagulants are given for the following conditions: a) prevention of deep vein thrombosis and pulmonary embolism; b) prevention of systemic emboli in patients with lone atrial fibrillation, atrial fibrillation associated or not with rheumatic heart disease, in patients with biological or mechanical cardiac valvular prostheses and in dilated cardiomyopathy; c) antithrombotic therapy in coronary heart disease and in coronary intervention; d) the interactions with oral anticoagulants and how to control these therapies are also discussed.

Effect of thrombolytic therapy on platelet expression and plasma concentration of PECAM-1 (CD31) in patients with acute myocardial infarction

Animal studies have shown that the administration of antibodies against platelet/endothelial cell adhesion molecule-1 (PECAM-1) before reperfusion can reduce infarct size. The purpose of the present study was to define the effects of thrombolytic therapy in acute myocardial infarction (AMI) patients on the platelet expression and plasma concentrations of PECAM-1 at prespecified time points after attempted reperfusion. The plasma concentration and platelet expression of PECAM-1 were determined in 23 AMI patients enrolled in the Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO-III) trial before thrombolysis and at 3, 6, 12, and 24 hours thereafter and compared with 22 healthy controls. At baseline, PECAM-1 was expressed significantly more on the platelet surface in the AMI patients than in controls (P=0.027) while soluble PECAM-1 plasma levels were almost identical between groups. There were no significant diurnal variations in both plasma and platelet PECAM-1 levels in controls. A significant decrease in platelet PECAM-1 expression was observed 3 hours after thrombolysis (P=0.03) compared with baseline, followed by a significant increase (P=0.004) in fluorescence intensity later at 24 hours after thrombolysis. Conversely, a significant increase in soluble PECAM-1 was observed 3 hours after thrombolysis (P=0.02), followed by a significant decrease later at 24 hours after attempted reperfusion (P=0.03). The expression of platelet-bound PECAM-1 is increased in AMI patients. Discordantly directed changes in soluble and platelet PECAM-1 after the first 24 hours after thrombolytic therapy may represent redistribution of the whole PECAM-1 pool. Further investigation of the possible role of PECAM-1 and the relationship between its soluble and platelet fractions in AMI are warranted.

Depressed platelet status in an elderly patient with hemorrhagic stroke after thrombolysis for acute myocardial infarction. GUSTO-III Investigators

BACKGROUND

Impaired platelet function has been reported in acute myocardial infarction (AMI) and stroke. However, prospective data on the changes of platelet status in patients before the occurrence of hemorrhagic stroke after thrombolytic therapy are unavailable.

CASE DESCRIPTION

An 86-year-old male patient was among the 23 AMI patients enrolled in the platelet study for the GUSTO-III trial. He received 325 mg of aspirin daily for at least 6 years, suffered an AMI, and was successfully reperfused with alteplase, but after 44 hours developed a large hemorrhagic stroke resulting in paraplegia. Platelet aggregation and receptor expression were measured by flow cytometry and ELISA before thrombolysis and at 3, 6, 12, and 24 hours thereafter. The percentage of platelet aggregation was lower in the stroke patient at every time point when induced by 5 micromol/L of ADP, by 10 micromol/L of ADP, and by thrombin than in the rest of the AMI group. Ristocetin and collagen-induced aggregability were within the group range. Decreased platelet glycoprotein Ib, IIb, IIIa, and IIb/IIIa and vitronectin receptor expression were observed in the stroke patient. No other differences in p24 (CD9), very late antigen-2, P-selectin, and platelet/endothelial cell adhesion molecule-1 expression were determined.

CONCLUSIONS

Profound depression of platelet status preceded the occurrence of hemorrhagic stroke in an elderly long-term aspirin user treated with thrombolytic therapy. Initial "exhausted" platelets may be responsible for the increased risk for hemorrhagic stroke after coronary thrombolysis.

Clinical characteristics and long-term outcome of patients in whom congestive heart failure develops after thrombolytic therapy for acute myocardial infarction: development of a predictive model

Ischemic heart disease is the most common cause of congestive heart failure, which often begins after acute myocardial infarction. To better delineate the clinical characteristics and outcomes of patients in whom congestive heart failure develops after acute myocardial infarction in the thrombolytic era, we prospectively evaluated patients enrolled in six of the TAMI trials. The study cohort comprised 1619 consecutive patients who had at least 1 mm of ST-segment elevation in two contiguous electrocardiographic leads within 6 hours of the onset of acute myocardial infarction and who received intravenous thrombolytic therapy. We prospectively collected clinical characteristics, baseline demographics, acute and 1-week angiographic variables, and in-hospital and 1-year outcome data. We performed stepwise multivariable regression analysis to determine the noninvasive and invasive predictors of the development of in-hospital congestive heart failure. Congestive heart failure developed in 301 patients in the hospital (19% of 1521 patients admitted were not in heart failure). These patients were likely to be older and female, have diabetes mellitus and previous myocardial infarction, and have an anterior wall myocardial infarction. On acute angiography, they had lower ejection fractions and a higher incidence of multivessel disease. Patency at 90 minutes was lower in the patients with congestive heart failure, and acute mitral regurgitation occurred in 1.6% versus 0.21% of patients without congestive heart failure. Patients with congestive heart failure had higher mortality, more in-hospital complications, and longer hospitalizations. At 1-year follow up, 21% of the patients in whom congestive heart failure developed had died versus 5% in the group without congestive heart failure. Predictors of new congestive heart failure included increased age, anterior wall myocardial infarction, lower pulse pressure and systolic blood pressure, diabetes mellitus, and the presence of rales on admission. The acute angiographic variables of reduced ejection fraction, increased number of diseased vessels, and attempted percutaneous intervention improved the concordance of the predictive model by 6%. Congestive heart failure remains a common clinical problem after acute myocardial infarction and is associated with a twofold increase in in-hospital morbidity and a fourfold increase in in-hospital and 1-year mortality. The development of congestive heart failure in the hospital can be predicted from noninvasive and invasive baseline characteristics. We present a simple table to predict congestive heart failure from baseline characteristics and invasive information.