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Biomedical subjects

Paul W Armstrong

Publications and source records attributed to Paul W Armstrong.

At least 19 recordsLinked to original sources
PubMed2004

Differential treatment benefit of platelet glycoprotein IIb/IIIa inhibition with percutaneous coronary intervention versus medical therapy for acute coronary syndromes: exploration of methods.

BACKGROUND: Although many believe that platelet glycoprotein IIb/IIIa inhibitors should be used only in acute coronary syndrome patients undergoing percutaneous coronary intervention, supporting data from randomized clinical trials are tenuous. The assumption that these agents are useful only in conjunction with percutaneous coronary intervention is based primarily on inappropriate subgroup analyses performed across the glycoprotein IIb/IIIa inhibitor trials. METHODS AND RESULTS: We describe the problems with these analytical techniques and demonstrate that different approaches to the question can result in opposing answers. CONCLUSIONS: Clinical-practice decisions and practice guidelines should be based on overall trial results and not analyses of post-randomization subgroups.

Acute Disease↗
PubMed2004

Renal insufficiency and heart failure: prognostic and therapeutic implications from a prospective cohort study.

BACKGROUND: The prevalence, prognostic import, and impact of renal insufficiency on the benefits of ACE inhibitors and beta-blockers in community-dwelling patients with heart failure are uncertain. METHODS AND RESULTS: We analyzed data from a prospective cohort of 754 patients with heart failure who had ejection fraction, serum creatinine, and weight measured at baseline. Median age was 69 years, and 43% had an ejection fraction > or =35%. By the Cockcroft-Gault equation, 118 patients (16%) had creatinine clearances < or =30 mL/min and 301 (40%) had creatinine clearances between 30 and 59 mL/min. During follow-up (median 926 days), 385 patients (37%) died. Even after adjustment for all other prognostic factors, survival was significantly associated with renal function (P=0.002) in patients with either systolic or diastolic dysfunction; patients exhibited a 1% increase in mortality for each 1-mL/min decrease in creatinine clearance. The associations with 1-year mortality reductions were similar for ACE inhibitors (OR 0.46 [95% CI 0.26 to 0.82] versus OR 0.28 [95% CI 0.11 to 0.70]) and beta-blockers (OR 0.40 [95% CI 0.23 to 0.70] versus OR 0.41 [95% CI 0.19 to 0.85]) in patients with creatinine clearances <60 mL/min versus > or =60 mL/min, although these drugs were used less frequently in patients with renal insufficiency. CONCLUSIONS: Renal insufficiency is more prevalent in patients with heart failure than previously reported and is an independent prognostic factor in diastolic and systolic dysfunction. ACE inhibitors and beta-blockers were associated with similar reductions in mortality in patients with and without renal insufficiency.

Adrenergic beta-Antagonists↗
PubMed2003

Impact of sex on long-term mortality from acute myocardial infarction vs unstable angina.

BACKGROUND: Patient sex has been shown to differentially affect mortality from unstable angina (UA) and acute myocardial infarction (AMI). However, to our knowledge, no prior population-based studies have examined both cohorts simultaneously to explain this intriguing variation. Hence, we undertook to explore and explain sex differences in 5-year mortality after UA and AMI. METHODS: We used an administrative database of 22 967 patients with AMI and 8441 patients with UA discharged from acute care hospitals in Alberta between April 1, 1993, and March 31, 2000. RESULTS: Women were older with more baseline comorbidities, more frequently had a diagnosis of UA, and had 30% lower relative odds of undergoing revascularization than men. Kaplan-Meier estimates of 5-year mortality were similar between sexes after UA (women vs men, 21.6% vs 19.5%; P =.09) but markedly higher for women after AMI (38.5% vs 26.6%, P<.001). After adjustment for baseline characteristics and revascularization, the hazard ratios (95% confidence intervals) for women vs men were 0.81 (0.72-0.92) after UA and 0.99 (0.93-1.05) after AMI. Only women younger than 65 years were at a significantly higher risk after AMI. The reasons for this difference in sex-related outcomes between UA and AMI may relate to greater disparities in the AMI cohort with respect to age, comorbidities, neighborhood incomes, and referrals to cardiovascular specialists. CONCLUSIONS: Relative to UA, AMI has a more serious impact on women than men, such that women have a survival advantage when afflicted with UA but lose that advantage with AMI. Additional investigation into the causes, treatment, and policy implications of the age-sex interaction is warranted.

Age Distribution↗
PubMed2003

From controlled trials to clinical practice: monitoring transmyocardial revascularization use and outcomes.

OBJECTIVES: We sought to examine trends in the use and outcomes of transmyocardial revascularization (TMR) in community practice. We also identified important risk factors for TMR and compared outcomes of TMR combined with coronary artery bypass graft surgery (TMR + CABG) versus bypass alone in patients receiving incomplete revascularization. BACKGROUND: Although it is approved for use as a stand-alone procedure, there are limited data on the outcomes of (TMR + CABG). METHODS: We identified 3,717 patients receiving TMR at 173 U.S. hospitals participating in the Society of Thoracic Surgeons (STS) National Cardiac Database. Baseline characteristics and outcomes in these patients were compared with those from six published randomized TMR trials. Multivariable logistic regression was used to identify clinical risk factors for mortality with TMR. Risk-adjusted mortality was also compared for TMR + CABG relative to CABG only in patients not amenable to complete traditional revascularization. RESULTS: Between January 1998 and December 2001, the number of STS hospitals performing TMR and total procedural counts increased markedly, driven predominately by more TMR + CABG cases. Overall mortality rates for TMR-alone and TMR + CABG were 6.4% and 4.2%, respectively. Operative risks were significantly higher in those patients with recent myocardial infarction, unstable angina, and depressed ventricular function. Among patients receiving incomplete revascularization, TMR + CABG was not associated with decreased mortality risk compared with CABG alone, adjusted odds ratio 1.11 (95% confidence interval 0.74 to 1.67). CONCLUSIONS: The use of TMR, and in particular, TMR + CABG, is expanding in community practice. Although procedural risks are high, there is room for optimization through improved patient selection and timing of the procedure. Further studies of TMR + CABG are needed given its growing use and unclear benefits.

Aged↗
PubMed2003

Outcome of urgent and elective percutaneous coronary interventions after pharmacologic reperfusion with tenecteplase combined with unfractionated heparin, enoxaparin, or abciximab.

OBJECTIVES: The aim of this study was to evaluate percutaneous coronary intervention (PCI) in the Assessment of the Safety and Efficacy of New Thrombolytic Regimens (ASSENT-3) trial. BACKGROUND: In the ASSENT-3 trial, co-therapy with abciximab (ABC) or enoxaparin (ENOX) reduced ischemic complications after ST-elevation acute myocardial infarction treated with tenecteplase when compared with unfractionated heparin (UFH). The effect of these new co-therapies on the results of PCI is unknown. METHODS: Clinical outcomes in patients who received co-therapy with ABC, ENOX, or UFH and subsequently underwent an elective (n = 1,064) or urgent (n = 716) PCI in the ASSENT-3 trial were compared. RESULTS: No significant differences in clinical end points were observed in patients who underwent an elective PCI. A non-significant trend toward fewer in-hospital myocardial re-infarctions was seen with ABC and ENOX when compared with UFH (0.5% vs. 0.6% vs. 1.5%, respectively). The incidence of bleeding complications was similar in the three treatment arms. Significantly fewer ABC- and ENOX-treated patients needed urgent PCI compared with UFH (9.1% vs. 11.9% vs. 14.3%; p < 0.0001), but outcomes in these patients were in general less favorable (30-day mortality: 8.2% vs. 5.4% vs. 4.5%; 1-year mortality: 11.0% vs. 8.5% vs. 5.6%; in-hospital re-infarction: 3.9% vs. 2.5% vs. 2.7%; major bleeding complications: 8.8% vs. 7.0% vs. 3.4%). In pairwise comparisons with UFH, the higher one-year mortality and major bleeding rates after ABC were statistically significant (p = 0.045 and p = 0.012, respectively). CONCLUSIONS: Clinical outcomes after elective PCI were similar with the three antithrombotic co-therapies studied in ASSENT-3. Although fewer patients needed urgent PCI with ABC and ENOX, clinical outcomes were less favorable in this selected population, especially with ABC.

Abciximab↗
PubMed2003

Effect of pexelizumab, an anti-C5 complement antibody, as adjunctive therapy to fibrinolysis in acute myocardial infarction: the COMPlement inhibition in myocardial infarction treated with thromboLYtics (COMPLY) trial.

BACKGROUND: Complement activation mediates myocardial damage that occurs during ischemia and reperfusion through multiple pathways. We performed 2 separate, parallel, double-blind, placebo-controlled trials to determine the effects of pexelizumab (a novel C5 complement monoclonal antibody fragment) on infarct size in patients receiving reperfusion therapy: COMPlement inhibition in myocardial infarction treated with thromboLYtics (COMPLY) and COMplement inhibition in Myocardial infarction treated with Angioplasty (COMMA). The COMPLY trial is reported here. METHODS AND RESULTS: Overall, 943 patients with acute ST-segment elevation myocardial infarction (MI) (20% with isolated inferior MI) receiving fibrinolysis were randomly assigned <6 hours after symptom onset to placebo, pexelizumab 2.0-mg/kg bolus, or pexelizumab 2.0-mg/kg bolus plus 0.05 mg/kg per h for 20 hours. Infarct size determined by creatine kinase-MB area under the curve was the primary analysis, which included patients who received at least some study drug and fibrinolysis (n=920). The median infarct size did not differ by treatment (placebo, 5230; bolus, 4952; bolus plus infusion, 5557 [ng/mL] x h; bolus versus placebo, P=0.85; bolus plus infusion versus placebo, P=0.81), nor did the 90-day composite incidence of death, new or worsening congestive heart failure, shock, or stroke (placebo, 18.6%; bolus, 18.4%; bolus plus infusion, 19.7%). Pexelizumab inhibited complement for 4 hours with bolus-only dosing and for 20 to 24 hours with bolus-plus-infusion dosing, with no increase in infections. CONCLUSIONS: When used adjunctively with fibrinolysis, pexelizumab blocked complement activity but reduced neither infarct size by creatine kinase-MB assessment nor adverse clinical outcomes.

Aged↗
PubMed2003

Pexelizumab, an anti-C5 complement antibody, as adjunctive therapy to primary percutaneous coronary intervention in acute myocardial infarction: the COMplement inhibition in Myocardial infarction treated with Angioplasty (COMMA) trial.

BACKGROUND: Complement, activated during myocardial ischemia and reperfusion, causes myocardial damage through multiple processes. The COMplement inhibition in Myocardial infarction treated with Angioplasty (COMMA) trial was performed to determine the effect of pexelizumab, a C5 complement inhibitor, on infarct size in patients with ST-segment-elevation myocardial infarction (MI) undergoing primary percutaneous coronary intervention. METHODS AND RESULTS: In COMMA, 960 patients with MI (20% isolated inferior MI) were randomized to placebo, pexelizumab 2.0-mg/kg bolus, or pexelizumab 2.0-mg/kg bolus and 0.05-mg/kg per h infusion for 20 hours. Infarct size by creatine kinase-MB area under the curve, the primary outcome, did not differ significantly between groups (placebo median, 4393; bolus pexelizumab, 4526; bolus plus infusion pexelizumab, 4713 [ng/mL] x h; P=0.89 for bolus versus placebo; P=0.76 for bolus plus infusion versus placebo), nor did the composite of 90-day death, new or worsening heart failure, shock, or stroke (placebo, 11.1%; bolus, 10.7%; bolus plus infusion, 8.5%). The ninety-day mortality rate was significantly lower with pexelizumab bolus plus infusion (1.8% versus 5.9% with placebo; nominal P=0.014); the bolus-only group had an intermediate mortality rate (4.2%). CONCLUSIONS: In patients with ST-elevation MI undergoing percutaneous coronary intervention, pexelizumab had no measurable effect on infarct size. However, the significant reduction in mortality suggests that pexelizumab may benefit patients through alternative novel mechanisms and provides impetus for additional investigation.

Aged↗
PubMed2003

Prognostic value of isolated troponin elevation across the spectrum of chest pain syndromes.

The risk of death or recurrent myocardial infarction (MI) in patients with chest pain and baseline isolated troponin elevation is unclear. To determine the early and short-term risk of death or MI associated with isolated troponin elevation across a spectrum of chest pain syndromes, we used baseline creatine kinase (CK)-MB and troponin data from the Platelet IIb/IIIa Antagonism for the Reduction of Acute Coronary Syndrome Events in a Global Organization Network (PARAGON) B troponin substudy, the Global Utilization of Strategies To Open Occluded Coronary Arteries (GUSTO) IIa troponin substudy, and the Chest Pain Evaluation by Creatine Kinase-MB, Myoglobin, and Troponin I (CHECKMATE) study. Patients were grouped into 1 of 4 categories based on marker status (troponin-positive/CK-MB-positive, troponin-positive/CK-MB-negative, troponin-negative/CK-MB-positive, or troponin-negative/CK-MB-negative). The adjusted odds of death or MI occurring at 24 hours and 30 days was assessed by baseline marker status using multivariable logistic regression, with the group negative for both markers used as the reference. Patients who were positive for both markers had the highest odds of the 24-hour and 30-day end point. The adjusted odds of the 30-day end point for patients with isolated troponin elevation were 1.3 (95% confidence interval 0.7 to 2.3) and 4.8 (95% confidence interval 1.4 to 16.0) for high- and low-risk patients, respectively. The risk for 24-hour and 30-day death or MI with isolated positive CK-MB results was lower than with isolated positive troponin results, and it was not significantly greater than if the 2 markers were negative. For patients with high- and low-risk chest pain, baseline troponin elevation without CK-MB elevation was associated with increased risk for early and short-term adverse outcomes. This suggests that these patients should be admitted to the hospital and monitored in either an intensive care or step-down unit.

Aged↗
PubMed2003

Implantable cardioverter defibrillators in primary and secondary prevention: a systematic review of randomized, controlled trials.

BACKGROUND: Sudden cardiac death is common in persons with cardiovascular disease. PURPOSE: To assess the efficacy of implantable cardioverter defibrillators (ICDs) in persons at increased risk for sudden cardiac death. DATA SOURCES: MEDLINE (1980-2002), EMBASE (1980-2002), Cochrane Controlled Clinical Trial Registry (2002, Volume 3), other databases, and conference proceedings. Primary study authors and device manufacturers were contacted, and bibliographies of relevant papers were hand searched. STUDY SELECTION: Randomized, controlled clinical trials evaluating ICDs versus usual care were selected. DATA EXTRACTION: Two reviewers extracted data independently. DATA SYNTHESIS: Eight trials were included in the final analysis (4909 patients, 1154 deaths). Compared with usual care (most commonly amiodarone therapy), ICDs significantly reduced sudden cardiac death (relative risk [RR], 0.43 [95% CI, 0.35 to 0.53]) and all-cause mortality (RR, 0.74 [CI, 0.67 to 0.82]). The included trials were divided a priori into two categories: secondary prevention (involving patients resuscitated after cardiac arrest or unstable ventricular tachycardia or ventricular fibrillation [ n = 1963]) and primary prevention (involving patients at increased risk for sudden cardiac death but without documented cardiac arrest, ventricular fibrillation, or ventricular tachycardia [ n = 2946]). Regardless of baseline risk, ICDs were equally efficacious in preventing sudden cardiac death in both types of trials (RR, 0.50 [CI, 0.38 to 0.66] for secondary prevention vs. 0.37 [CI, 0.27 to 0.50] for primary prevention). However, the magnitude of benefit in total mortality varied within the primary prevention trials depending on baseline risk for sudden cardiac death. CONCLUSIONS: Implantable cardioverter defibrillators prevent sudden cardiac death regardless of baseline risk. However, their impact on total mortality is sensitive to baseline risk for arrhythmic death. Decisions about resource allocation for ICDs depend on accurate stratification of patients according to risk.

Arrhythmias, Cardiac↗
PubMed2003

Impact of on-site cardiac interventional facilities on management and outcome of patients with acute coronary syndromes.

OBJECTIVES: To investigate the impact of on-site cardiac interventional facilities on the management and outcome of patients with versus those without ST elevation acute coronary syndromes (ACS) in the Canadian-American Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO) IIb population. METHODS: Data from 4605 patients were analyzed in relation to the admitting hospital's capability to perform coronary procedures (noninvasive, angiography-capable and interventional hospitals). Differences in medication use, revascularization rate and patient outcome were determined. RESULTS: Whereas medication use during hospitalization and at discharge differed between non-ST elevation ACS patients treated in the three groups, these were generally more comparable among ST elevation ACS patients. In both ST segment cohorts, patients treated in interventional hospitals underwent coronary procedures more often (angiography rate greater than 70% versus 40% for noninvasive hospitals) and sooner (median two to three days versus four days in noninvasive hospitals) than those treated in other hospitals. Recurrent ischemia was significantly less common in non-ST elevation ACS patients treated in interventional hospitals (32% versus 36% in angiography-capable and 40% in noninvasive hospitals, P<0.001) and tended to be less common among ST elevation ACS patients treated in interventional hospitals. Patients treated in interventional hospitals tended to have lower mortality in the non-ST elevation ACS cohort but significantly fewer died in the ST elevation ACS during hospitalization and at 30 days, six months and one year (8.8% versus 11% in angiography-capable and 15% in noninvasive hospitals, P=0.015). These differences in mortality persisted after adjustment for key baseline covariates. Separate analysis of Canadian and American patients revealed similar mortality patterns, as to the total population, in both ST segment cohorts. CONCLUSIONS: Presence of an on-site cardiac interventional facility favourably affected the management and outcome of ACS patients in both non-ST and ST elevation cohorts.

Acute Disease↗
PubMed2003

Troponin T and quantitative ST-segment depression offer complementary prognostic information in the risk stratification of acute coronary syndrome patients.

OBJECTIVES: Our primary objective was to examine the prognostic relationship between baseline quantitative ST-segment depression (ST) and cardiac troponin T (cTnT) elevation. The secondary objectives were to: 1) examine whether ST provided additional insight into therapeutic efficacy of glycoprotein IIb/IIIa therapy similar to that demonstrated by cTnT; and 2) explore whether the time to evaluation impacted on each marker's relative prognostic utility. BACKGROUND: The relationship between the baseline electrocardiogram (ECG) and cTnT measurements in risk-stratifying patients presenting with acute coronary syndromes (ACS) has not been evaluated comprehensively. METHODS: The study population consisted of 959 patients enrolled in the cTnT substudy of the Platelet IIb/IIIa Antagonism for the Reduction of Acute coronary syndrome events in a Global Organization Network (PARAGON)-B trial. Patients were classified as having no ST (n = 387), 1 mm ST (n = 433), and ST > or =2 mm (n = 139). Forty-percent (n = 381) were classified as cTnT-positive based on a definition of > or =0.1 ng/ml. RESULTS: Six-month death/(re)myocardial infarction rates were 8.4% among cTnT-negative patients with no ST and 26.8% among cTnT-positive patients with ST > or =2 mm. On ECGs done after 6 h of symptom onset, ST > or =2 mm was associated with higher risk compared to its presence on ECGs done earlier (odds ratio [OR] 7.3 vs. 2.1). In contrast, the presence of elevated cTnT within 6 h of symptom was associated with a higher risk of adverse events compared with elevations after 6 h (OR 2.4 vs. 1.5). CONCLUSIONS: Quantitative ST and cTnT status are complementary in assessing risk among ACS patients and both should be employed to determine prognosis and assist in medical decision making.

Acetates↗
PubMed2003

Randomized evaluation of the safety and efficacy of enoxaparin versus unfractionated heparin in high-risk patients with non-ST-segment elevation acute coronary syndromes receiving the glycoprotein IIb/IIIa inhibitor eptifibatide.

BACKGROUND: Current pharmacotherapeutic options for high-risk non-ST-segment elevation acute coronary syndrome patients include aspirin, clopidogrel, heparin, and platelet glycoprotein IIb/IIIa inhibition. A key issue of uncertainty is the safety and efficacy of combination glycoprotein IIb/IIIa inhibitor and low-molecular-weight heparin therapy. METHODS AND RESULTS: We randomized 746 patients with rest ischemic discomfort within 24 hours after the onset of symptoms and ST-segment deviation and/or elevation of serum cardiac markers to receive open-label enoxaparin (1 mg/kg subcutaneously twice daily) or unfractionated heparin (70-U/kg bolus; 15 U x kg(-1) x h(-1) infusion, titrated to an activated partial thromboplastin time of 1.5 to 2 times control) for 48 hours. All patients received aspirin and eptifibatide (180- microg/kg bolus; 2 microg x kg(-1) x min(-1) infusion). Major non-coronary artery bypass surgery-related bleeding at 96 hours (primary safety outcome) was significantly lower among enoxaparin-treated patients than among heparin-treated patients (1.8% versus 4.6%, P=0.03). Minor bleeding was more frequent in the enoxaparin group (30.3% versus 20.8%, P=0.003). Patients in the enoxaparin group were less likely to experience ischemia as detected by continuous ECG evaluation (primary efficacy outcome) during the initial (14.3% versus 25.4%, P=0.0002) and subsequent (12.7% versus 25.9%, P<0.0001) 48-hour monitoring periods. Death or myocardial infarction at 30 days was significantly lower in the enoxaparin group (5% versus 9%, P=0.031). CONCLUSIONS: When aspirin and eptifibatide are used in high-risk non-ST-segment elevation acute coronary syndrome patients, enoxaparin improves outcomes (determined on the basis of better safety and efficacy) compared with currently recommended unfractionated heparin therapy and provides a useful novel alternative therapeutic strategy.

Acute Disease↗