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Biomedical subjects

Gregory A Braden

Publications and source records attributed to Gregory A Braden.

8 recordsLinked to original sources
PubMed2006

Chronic total coronary occlusions.

Chronic total coronary occlusions (CTO) occur in up to one-third of patients undergoing coronary angiography. Indications for opening CTOs include relief of angina, improving left ventricular function, decreasing the need for coronary artery bypass surgery, and improved long-term survival. Newer technology, wire-based and non-wired-based, has improved the ability to cross these previously uncrossable lesions, thereby improving the acute success rates of opening these lesions. Also, the advent of drug-eluting stents has markedly increased the long-term patency of these complex lesions. Therefore, the clinical demand for opening these chronically occluded arteries has increased.

Angioplasty, Balloon, Coronary↗
PubMed2004

Final results of the ReoPro readministration registry.

Because of its potential for antigenicity, theoretical concerns related to readministration of abciximab have been raised. We conducted the ReoPro Readministration Registry to assess the efficacy and safety of abciximab readministration. A total of 1,342 patients who underwent percutaneous coronary intervention and who received abciximab for at least a second time were recruited. Safety end points were hypersensitivity reactions, major bleeding, and thrombocytopenia (TCP). Human antichimeric antibody (HACA) titers were determined before and after readministration. Procedural success was 98% and was not influenced by the number of courses of abciximab or the presence of HACA. There were no cases of anaphylaxis. There were 5 minor allergic reactions, none of which required termination of the infusion. Clinically significant bleeding occurred in 31 patients (2.3%), including 1 (0.07%) with intracranial hemorrhage. TCP (<100 x 10(9)/L) developed in 5% of patients; profound TCP (<20 x 10(9)/L) occurred in 2%. In patients who received abciximab within 1 month of a previous treatment (n = 115), the risk of developing TCP and profound TCP was 16.5% and 12.2%, respectively. Having a positive HACA before readministration was not correlated with adverse clinical outcomes or bleeding, but was associated with TCP (14.1% vs 4.4%, p = 0.002) and profound TCP (5.6% vs 1.6%, p = 0.036). Readministration of abciximab can be accomplished without severe allergic responses and with a bleeding and efficacy profile similar to first-time administration. However, the rate of severe and profound TCP is increased relative to first-time administration, particularly when the time between treatments is <30 days or when HACA is present.

Abciximab↗
PubMed2003

A novel point-of-care enoxaparin monitor for use during percutaneous coronary intervention. Results of the Evaluating Enoxaparin Clotting Times (ELECT) Study.

OBJECTIVES: The aim of this study was to discern a target range of anticoagulation for enoxaparin during percutaneous coronary intervention (PCI) as measured by the Rapidpoint ENOX (Pharmanetics Inc., Morrisville, North Carolina), a new point-of-care test. BACKGROUND: In the U.S., enoxaparin has been used in only a small proportion of PCI procedures, partly because a rapid enoxaparin-specific assay was unavailable. METHODS: We analyzed data from 445 enrolled patients receiving subcutaneous or intravenous enoxaparin in a prospective, multicenter study. Serial anticoagulation measurements and clinical outcomes were recorded. RESULTS: The in-hospital composite occurrence of death, myocardial infarction, and urgent target vessel revascularization was 5.4%, and Thrombolysis In Myocardial Infarction (TIMI) major bleeding, minor bleeding, and any reported bleeding occurred in 0.2%, 1.3%, and 7.9% of patients, respectively. No significant association between procedural ENOX times and ischemic events was observed (p = 0.222), although the event rate was 4.0% among those with ENOX times between 250 to 450 s versus 7.2% for those outside this range (p = 0.134). Increasing ENOX time at sheath removal was correlated with any bleeding (p = 0.010) with a 1% increase for every approximately 30-s rise. CONCLUSIONS: Ischemic events were infrequent, and the rate appeared lowest in the mid-range of ENOX times. Bleeding events increased with increasing ENOX times. These observations, combined with a suggested procedural anti-Xa level of 0.8 to 1.8 IU/ml, translate into a recommended ENOX time range of 250 to 450 s for PCI and <200 to 250 s for sheath removal.

Angioplasty, Balloon, Coronary↗
PubMed2003

Evaluation of a novel point-of-care enoxaparin monitor with central laboratory anti-Xa levels.

BACKGROUND: Measurement of enoxaparin's anticoagulant activity has been limited to specialized coagulation laboratories and has been impractical for areas needing rapid results, such as during coronary angioplasty. A new point-of-care device, Rapidpoint ENOX, was recently developed to measure clotting times with enoxaparin use. OBJECTIVES: To correlate ENOX times with anti-Xa levels among patients receiving enoxaparin. METHODS: A total of 166 patients receiving enoxaparin for the prevention of deep venous thrombosis or as treatment during acute coronary syndromes or angioplasty were prospectively studied. Citrated and non-citrated whole-blood (CWB and NCWB) samples were obtained at baseline and peak enoxaparin activity. ENOX times were measured with whole-blood, and the Stachrom anti-Xa assay was performed on the plasma from the remainder of the samples. The Pearson correlation coefficient was used to assess the relationship between these two assays. RESULTS: There was a strong linear correlation between the ENOX times and the anti-Xa activities for both CWB (r=0.89, p<0.001) and NCWB (r=0.82, p<0.001) when considering all 332 samples (baseline and peak). When baseline samples were excluded, the correlation remained strong for CWB ENOX times and anti-Xa levels (r=0.84, p<0.001), but was only moderate for NCWB (r=0.73, p<0.001). A CWB ENOX time of </=160 s corresponded to anti-Xa level of </=0.5 IU/ml in 95% (188/197) of patients. A CWB ENOX time >/=200 s corresponded to anti-Xa levels >/=0.8 IU/ml in 96% (93/96) of patients. CONCLUSIONS: Rapidpoint ENOX times correlate strongly to anti-Xa activities measured by the Stachrom Heparin Assays for citrated whole-blood samples. This novel test can be used for rapid bedside measurements of enoxaparin anticoagulant activity.

Aged↗
PubMed2002

Vascular closure devices in patients treated with anticoagulation and IIb/IIIa receptor inhibitors during percutaneous revascularization.

OBJECTIVES: The study assessed clinical outcomes of closure device use following percutaneous coronary revascularization using current standards of anticoagulation and antiplatelet therapy. BACKGROUND: Evaluation of the outcomes of patients by use of vascular closure devices during coronary interventions employing current standards of anticoagulation and glycoprotein (GP) IIb/IIIa inhibitor therapy is limited. METHODS: We evaluated outcomes of 4,525 consecutive patients who underwent percutaneous coronary intervention between July 1997 and April 2000. All patients received anticoagulation with heparin and GP IIb/IIIa inhibitor therapy with abciximab. The closure method was manual in 1,824 patients, Angioseal in 524 patients and Perclose in 2,177 patients. Procedural and hospital vascular outcomes were evaluated. RESULTS: Closure device success was 97.1% Angioseal and 94.1% Perclose (p < 0.05). Minor vascular complications occurred in 1.8% of manual patients, 1.1% of Angioseal patients and 1.2% of Perclose patients (p = NS); major complications occurred in 1.3% of manual patients, 1.1% of Angioseal patients and 1.0% of Perclose patients (p = NS). Multivariate logistic regression identified only closure device failure as an independent predictor of a vascular complication. In patients with successful closure with a device, minor complications (0.8% vs. 1.8%, p < 0.05) and any complication (1.5% vs. 2.5%, p < 0.05) were reduced compared to manual compression. CONCLUSIONS: Arterial closure following coronary interventions using anticoagulation and GP IIb/IIIa inhibitor therapy can be safely and effectively performed, with vascular complication rates similar to or lower than with manual pressure. Additionally, vascular complication rates using GP IIb/IIIa inhibitor therapy regardless of the method of arterial closure are equivalent to or lower than previously published rates of vascular complications.

Abciximab↗
PubMed2002

Reduced inhibition by abciximab in platelets with the PlA2 polymorphism.

BACKGROUND: The PlA2 polymorphism of the glycoprotein IIb/IIIa (fibrinogen) receptor has been associated with increased restenosis and stent thrombosis. We postulated that this allele could alter the antiplatelet effect of abciximab in patients undergoing percutaneous coronary intervention. METHODS: Optical platelet aggregation assays, Ultegra (Accumetrics, San Diego) rapid platelet function assays, and radiometric abciximab binding assays were performed in 66 Pl(A1/A1) and 21 PlA1/A2 patients undergoing percutaneous coronary interventions. The affinity of abciximab for the PlA1 and PlA2 receptors was determined with use of transfected cells. RESULTS: Compared with PlA1/A1 homozygotes, PlA1/A2 platelets were less completely inhibited after abciximab bolus (P =.002) and at 24 hours (P =.02) as assessed by the rapid platelet function assays. Optical aggregation assays confirmed that Pl(A1/A2) platelets were less completely inhibited after abciximab bolus (P =.05). The radiometric abciximab binding assay demonstrated that the PlA1/A2 platelets had fewer baseline fibrinogen receptors than did the PlA1/A1 platelets (P =.04) and more free fibrinogen receptors at 24 hours (P =.008). Cells transfected to express homozygous PlA1 or PlA2 demonstrated a nonsignificant trend (P =.12) for reduced abciximab affinity for PlA2. CONCLUSIONS: PlA1/A2 platelets are less completely inhibited with abciximab, contributing to the observed interindividual variability in platelet function inhibition. Because the extent of platelet inhibition is an independent predictor for the risk of major adverse coronary events after percutaneous coronary intervention, the relative resistance of PlA2-positive platelets may contribute to a less favorable outcome in these patients.

Abciximab↗
PubMed2002

The Ultegra rapid platelet-function assay: comparison to standard platelet function assays in patients undergoing percutaneous coronary intervention with abciximab therapy.

BACKGROUND: Despite the proven benefit of glycoprotein IIb/IIIa inhibitors during percutaneous coronary intervention, significant interpatient variability exists in antiplatelet response. Furthermore, a diminished degree of platelet inhibition is an independent predictor of adverse cardiac events, highlighting the need for accurate and precise monitoring of platelet function. METHODS: Patients (n = 192) who underwent elective percutaneous coronary intervention at 4 centers were enrolled. The following 3 time points were studied: 1, baseline, before abciximab bolus administration; 2, during, within 1 hour of abciximab bolus administration; and 3, post, 24 hours after abciximab bolus administration or at the time of patient discharge, whichever occurred first. The following 3 assays were compared at all time points: Ultegra rapid platelet-function assay (Ultegra RPFA), conventional turbidometric platelet aggregometry, and receptor binding assay with [125I]-abciximab. Variability in Ultegra RPFA measurements between operators was determined with performance of the assays at the point of care and in the laboratory. A sub-study of 22 patients at 1 center was performed in which the laboratory scientist performed all 3 assays in duplicate at each time point. RESULTS: Comparison with the receptor binding assay and conventional platelet aggregometry in 120 patients showed that the Ultegra RPFA correlated with aggregometry (r = 0.89) and with the receptor binding assay (r = 0.89). There was good agreement (r = 0.80) between values obtained by intended users and those obtained by laboratory scientists. Furthermore, Ultegra RPFA values had equivalent precision to the standard assays. CONCLUSION: The Ultegra RPFA has equivalent accuracy and precision when compared with the 2 reference assays studied. Ultegra RPFA measurements are not operator-dependent and are not influenced by concomitant medications, hematologic parameters, or demographics.

Abciximab↗