C. Michael Gibson

Abciximab Facilitates the Rate and Extent of Thrombolysis Results of the Thrombolysis In Myocardial Infarction (TIMI) 14 Trial

BACKGROUND The TIMI 14 trial tested the hypothesis that abciximab, the Fab fragment of a monoclonal antibody directed to the platelet glycoprotein (GP) IIb/IIIa receptor, is a potent and safe addition to reduced-dose thrombolytic regimens for ST-segment elevation MI. METHODS AND RESULTS Patients (n=888) with ST-elevation MI presenting <12 hours from onset of symptoms were treated with aspirin and randomized initially to either 100 mg of accelerated-dose alteplase (control) or abciximab (bolus 0.25 mg/kg and 12-hour infusion of 0.125 microg. kg-1. min-1) alone or in combination with reduced doses of alteplase (20 to 65 mg) or streptokinase (500 000 U to 1.5 MU). Control patients received standard weight-adjusted heparin (70-U/kg bolus; infusion of 15 U. kg-1. h-1), whereas those treated with a regimen including abciximab received low-dose heparin (60-U/kg bolus; infusion of 7 U. kg-1. h-1). The rate of TIMI 3 flow at 90 minutes for patients treated with accelerated alteplase alone was 57% compared with 32% for abciximab alone and 34% to 46% for doses of streptokinase between 500 000 U and 1.25 MU with abciximab. Higher rates of TIMI 3 flow at both 60 and 90 minutes were observed with increasing duration of administration of alteplase, progressing from a bolus alone to a bolus followed by either a 30- or 60-minute infusion (P<0.02). The most promising regimen was 50 mg of alteplase (15-mg bolus; infusion of 35 mg over 60 minutes), which produced a 76% rate of TIMI 3 flow at 90 minutes and was tested subsequently in conjunction with either low-dose or very-low-dose (30-U/kg bolus; infusion of 4 U. kg-1. h-1) heparin. TIMI 3 flow rates were significantly higher in the 50-mg alteplase plus abciximab group versus the alteplase-only group at both 60 minutes (72% versus 43%; P=0.0009) and 90 minutes (77% versus 62%; P=0.02). The rates of major hemorrhage were 6% in patients receiving alteplase alone (n=235), 3% with abciximab alone (n=32), 10% with streptokinase plus abciximab (n=143), 7% with 50 mg of alteplase plus abciximab and low-dose heparin (n=103), and 1% with 50 mg of alteplase plus abciximab with very-low-dose heparin (n=70). CONCLUSIONS Abciximab facilitates the rate and extent of thrombolysis, producing early, marked increases in TIMI 3 flow when combined with half the usual dose of alteplase. This improvement in reperfusion with alteplase occurred without an increase in the risk of major bleeding. Substantial reductions in heparin dosing may reduce the risk of bleeding even further. Modest improvements in TIMI 3 flow were seen when abciximab was combined with streptokinase, but there was an increased risk of bleeding.

High levels of platelet inhibition with abciximab despite heightened platelet activation and aggregation during thrombolysis for acute myocardial infarction: results from TIMI (thrombolysis in myocardial infarction) 14.

BACKGROUND We evaluated platelet activation and aggregation in patients with acute myocardial infarction (AMI) treated with thrombolytic therapy alone or with reduced-dose thrombolysis and concomitant abciximab. METHODS AND RESULTS The study was performed in 20 control subjects and 51 patients with AMI before and after reperfusion with either alteplase or reteplase or reduced doses of these agents with concomitant abciximab. Platelet activation was assayed by platelet surface expression of P-selectin. Turbidometric platelet aggregation in response to ADP was measured in patients before thrombolytic therapy and 90 minutes and 24 hours after the beginning of thrombolytic therapy. P-selectin expression was greater at baseline in patients than normal control subjects (30.4% versus 9. 8%, P<0.0001) but was identical between the 2 groups after stimulation with ADP (64.4% versus 69.3%, P=0.37). However, at 24 hours, basal P-selectin expression declined in patients (P=0.0025 versus baseline), whereas ADP-stimulated P-selectin expression was lower in patients than in control subjects (48% versus 69%, P=0. 0004). When combined with reduced doses of either alteplase or reteplase, abciximab achieved 91% and 83% inhibition of 5 and 20 micromol/L ADP-induced platelet aggregation, which decreased to 46% and 40%, respectively, at 24 hours. No appreciable difference in the platelet inhibition profile of abciximab was observed between the 2 thrombolytics. CONCLUSIONS Platelet activation and aggregation are heightened in the setting of thrombolysis for AMI. Despite this enhanced level of platelet activation, abciximab, combined with a reduced-dose thrombolytic, inhibited platelet aggregation similarly to the level reported in elective settings.

Clinically significant bleeding with low-dose rivaroxaban versus aspirin, in addition to P2Y12 inhibition, in acute coronary syndromes (GEMINI-ACS-1): a double-blind, multicentre, randomised trial

BACKGROUND Dual antiplatelet therapy (DAPT), aspirin plus a P2Y12 inhibitor, is the standard antithrombotic treatment following acute coronary syndromes. The factor Xa inhibitor rivaroxaban reduced mortality and ischaemic events when added to DAPT, but caused increased bleeding. The safety of a dual pathway antithrombotic therapy approach combining low-dose rivaroxaban (in place of aspirin) with a P2Y12 inhibitor has not been assesssed in acute coronary syndromes. We aimed to assess rivaroxaban 2·5 mg twice daily versus aspirin 100 mg daily, in addition to clopidogrel or ticagrelor (chosen at investigator discretion before randomisation), for patients with acute coronary syndromes started within 10 days after presentation and continued for 6-12 months. METHODS In this double-blind, multicentre, randomised trial (GEMINI-ACS-1) done at 371 clinical centres in 21 countries, eligible patients were older than 18 years with unstable angina, non-ST segment elevation myocardial infarction (NSTEMI) or ST segment elevation myocardial infarction (STEMI), with positive cardiac biomarkers and either ischaemic electrocardiographic changes or an atherosclerotic culprit lesion identified during angiography. Participants were randomly assigned (1:1) within 10 days after admission for the index acute coronary syndromes event to either aspirin or rivaroxaban based on a computer-generated randomisation schedule. Randomisation was balanced by using randomly permuted blocks with size of four and was stratified based on the background P2Y12 inhibitor (clopidogrel or ticagrelor) intended to be used at the time of randomisation. Investigators and patients were masked to treatment assignment. Patients received a minimum of 180 days of double-blind treatment with rivaroxaban 2·5 mg twice daily or aspirin 100 mg daily. The choice of clopidogrel or ticagrelor during trial conduct was not randomised and was based on investigator preference. The primary endpoint was thrombolysis in myocardial infarction (TIMI) clinically significant bleeding not related to coronary artery bypass grafting (CABG; major, minor, or requiring medical attention) up to day 390. Primary analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT02293395. FINDINGS Between April 22, 2015, and Oct 14, 2016, 3037 patients with acute coronary syndromes were randomly assigned; 1518 to receive aspirin and 1519 to receive rivaroxaban. 1704 patients (56%) were in the ticagrelor and 1333 (44%) in the clopidogrel strata. Median duration of treatment was 291 days (IQR 239-354). TIMI non-CABG clinically significant bleeding was similar with rivaroxaban versus aspirin therapy (total 154 patients [5%]; 80 participants [5%] of 1519 vs 74 participants [5%] of 1518; HR 1·09 [95% CI 0·80-1·50]; p=0·5840). INTERPRETATION A dual pathway antithrombotic therapy approach combining low-dose rivaroxaban with a P2Y12 inhibitor for the treatment of patients with acute coronary syndromes had similar risk of clinically significant bleeding as aspirin and a P2Y12 inhibitor. A larger, adequately powered trial would be required to definitively assess the efficacy and safety of this approach. FUNDING Janssen Research & Development and Bayer AG.

Weight-adjusted dosing of TNK-tissue plasminogen activator and its relation to angiographic outcomes in the thrombolysis in myocardial infarction 10B trial

Fixed doses of thrombolytic agents are generally administered to patients of varying body weights, and the dose-response relation may be confounded by the variability in patient weight. We hypothesized that higher doses of TNK-tissue plasminogen activator (tPA) per unit body weight would be related to improved flow at 90 minutes after thrombolytic administration. A total of 886 patients with acute myocardial infarction were randomized to receive either a single bolus of 30, 40, or 50 mg of TNK-tPA or front-loaded tPA in the Thrombolysis In Myocardial Infarction (TIMI) 10B trial. The dose of TNK-tPA administered was divided by the patients weight to arrive at the TNK-tPA dose (mg) per unit body weight (kg), and patients were stratified into tertiles based on mg/kg of TNK-tPA: low dose, 0.2 to 0.39 mg/kg; mid-dose, 0.40 to 0.51 mg/kg; high dose, 0.52 to 1.24 mg/kg. Flow in the culprit and nonculprit arteries was analyzed using the TIMI flow grades and the corrected TIMI frame count (CTFC). The median CTFC in culprit arteries differed between the tertiles (3-way p = 0.007), with the CTFC being 7.2 frames faster in high-dose than in low-dose patients (43.1 +/- 30.1, median 31.2, n = 171 vs 54.6 +/- 34.8, median 38.4, n = 166, 2-way p = 0.002). Patients in the mid- and high-dose tertiles achieved patency more frequently (TIMI grade 2 or 3 flow) by 60 minutes (p = 0.02), and the 90-minute percent diameter stenosis was less severe in patients in the high- versus low-dose tertile (p = 0.03). In nonculprit arteries, the CTFC was faster in high- than in low-dose tertiles (29.6 +/- 13.4, median 26.9, n = 130 vs 34.7 +/- 16.3, median 32.8, n = 108, 3-way p = 0.03, 2-way p = 0.008). In patients who underwent percutaneous transluminal coronary angioplasty (PTCA), the CTFC in culprit arteries after PTCA was fastest in the high- and mid-dose tertiles than in those receiving low doses (2-way p = 0.05). Thus, higher doses per unit body weight of TNK-tPA result in not only faster culprit artery flow, but also faster nonculprit, global, and post-PTCA flow, which may reflect earlier opening, reduced stunning, or improved microvascular function. The greater effectiveness of thrombolysis must be weighed against any increase in risk.

Frequency and Predictors of Internal Mammary Artery Graft Failure and Subsequent Clinical Outcomes: Insights From the Project of Ex-vivo Vein Graft Engineering via Transfection (prevent) Iv Trial

Background —The internal mammary artery (IMA) is the preferred conduit for bypassing the left anterior descending (LAD) artery in patients undergoing coronary artery bypass grafting (CABG). Systematic evaluation of the frequency and predictors of IMA failure and long-term outcomes is lacking. Methods and Results —PREVENT IV trial participants who underwent IMA-LAD revascularization and had 12-18-month angiographic follow-up (n=1539) were included. Logistic regression with fast false selection rate methods was used to identify characteristics associated with IMA failure (≥75% stenosis). The relationship between IMA failure and long-term outcomes including death, myocardial infarction, and repeat revascularization was assessed using Cox regression. IMA failure occurred in 132 participants (8.6%). Predictors of IMA graft failure were LAD stenosis <75% (odds ratio [OR], 1.76; 95% confidence interval [CI], 1.19-2.59), additional bypass graft to diagonal branch (OR, 1.92; 95% CI, 1.33-2.76), and not having diabetes (OR, 1.82; 95% CI, 1.20-2.78). LAD stenosis and additional diagonal graft remained predictive of IMA failure in an alternative model that included angiographic failure or death before angiography as the outcome. IMA failure was associated with a significantly higher incidence of subsequent acute (<14 days of angiography) clinical events, mostly due to a higher rate of repeat revascularization. Conclusions —IMA failure was common and associated with higher rates of repeat revascularization, and patients with intermediate LAD stenosis or with an additional bypass graft to the diagonal branch had increased risk for IMA failure. These findings raise concerns regarding competitive flow and the benefit of CABG in intermediate LAD stenosis without functional evidence of ischemia. Clinical Trial Registration Information —ClinicalTrials.gov. Identifier: NCT00042081.Background— The internal mammary artery (IMA) is the preferred conduit for bypassing the left anterior descending (LAD) artery in patients undergoing coronary artery bypass grafting. Systematic evaluation of the frequency and predictors of IMA failure and long-term outcomes is lacking. Methods and Results— The Project of Ex-vivo Vein Graft Engineering via Transfection (PREVENT) IV trial participants who underwent IMA-LAD revascularization and had 12- to 18-month angiographic follow-up (n=1539) were included. Logistic regression with fast false selection rate methods was used to identify characteristics associated with IMA failure (≥75% stenosis). The relationship between IMA failure and long-term outcomes, including death, myocardial infarction, and repeat revascularization, was assessed with Cox regression. IMA failure occurred in 132 participants (8.6%). Predictors of IMA graft failure were LAD stenosis <75% (odds ratio, 1.76; 95% confidence interval, 1.19–2.59), additional bypass graft to diagonal branch (odds ratio, 1.92; 95% confidence interval, 1.33–2.76), and not having diabetes mellitus (odds ratio, 1.82; 95% confidence interval, 1.20–2.78). LAD stenosis and additional diagonal graft remained predictive of IMA failure in an alternative model that included angiographic failure or death before angiography as the outcome. IMA failure was associated with a significantly higher incidence of subsequent acute (<14 days of angiography) clinical events, mostly as a result of a higher rate of repeat revascularization. Conclusions— IMA failure was common and associated with higher rates of repeat revascularization, and patients with intermediate LAD stenosis or with an additional bypass graft to the diagonal branch had increased risk for IMA failure. These findings raise concerns about competitive flow and the benefit of coronary artery bypass grafting in intermediate LAD stenosis without functional evidence of ischemia. Clinical Trial Registration— URL: http:/www.clinicaltrials.gov. Unique identifier: NCT00042081.

Radial versus femoral access, bleeding and ischemic events in patients with non-ST-segment elevation acute coronary syndrome managed with an invasive strategy

BACKGROUND Bleeding is a major limitation of antithrombotic therapy among invasively managed non-ST-segment elevation acute coronary syndromes (NSTE-ACS) patients; therefore, we examined the use of radial access and its association with outcomes among NSTE-ACS patients. METHODS Clinical characteristics and geographic variation in radial access were examined, as well as its association with bleeding, red blood cell transfusion and ischemic outcomes (96-hour death/myocardial infarction/recurrent ischemic/thrombotic bailout; 30-day death/myocardial infarction; 1-year death) in the EARLY versus delayed, provisional eptifibatide in acute coronary syndromes trial. RESULTS Of 9126 patients, 13.5% underwent radial-access catheterization. Female sex, age, weight, and prior revascularization were inversely associated with radial access, and its use varied widely by country (2%-97%). There were fewer GUSTO severe/moderate bleeds and red blood cell transfusions in the radial access group; however, it was attenuated after adjustment (odds ratio 0.73, 95% confidence intervals [CI] [0.50-1.06], P = .094 and 1.00 [0.71-1.40] P = .991). Ischemic outcomes did not differ by access site. CONCLUSIONS In this post hoc analysis of a large clinical trial, there was significant international variation in use of radial access for NSTE-ACS patients undergoing invasive management, and it was preferentially used in those at lower risk for bleeding. Radial approach was not associated with a significant reduction in either bleeding or ischemic outcomes. Further study is needed to determine whether wider application of radial approach to acute coronary syndrome patients at high risk for bleeding improves overall outcomes.

Insights into the Pathophysiology of Acute Ischemic Syndromes Using the TIMI Flow Grade, TIMI Frame Count, and TIMI Myocardial Perfusion Grade

For over a decade now, the Thrombolysis in Myocardial Infarction (TIMI) flow grade classification scheme has been successfully used to assess coronary blood flow in acute coronary syndromes (1). Although this scheme has been a valuable tool for comparing the efficacy of reperfusion strategies and in identifying patients at higher risk for adverse outcomes in acute coronary syndromes, there are limitations to this classification scheme (2,3). To overcome these limitations, the TIMI Angiographic Core Laboratory developed a new index of coronary blood flow called the TIMI frame count (2). In contrast to the TIMI flow grades (TFGs), which are subjective categorical variables, the TIMI frame count is an objective continuous variable of epicardial flow (2). There has also been a recent shift toward focus on microvascular perfusion. One method developed to assess tissue level perfusion is the TIMI myocardial perfusion grade (TMPG) (4). The goal of this chapter is to review these three methods and to discuss the insights into the pathophysiology of acute coronary syndromes provided by these indexes of coronary blood flow and myocardial perfusion.

THE EFFICACY AND SAFETY OF CANGRELOR FOR PATIENTS UNDERGOING SINGLE VESSEL VERSUS MULTI VESSEL PERCUTANEOUS CORONARY INTERVENTION: INSIGHTS FROM THE CHAMPION PHOENIX TRIAL

The intravenous, rapidly acting P2Y12 inhibitor cangrelor reduces the rate of ischemic events during percutaneous coronary intervention (PCI) with no significant increase in severe bleeding. This study aimed to evaluate the efficacy and safety of cangrelor in patients treated with single vessel (SV

THE EFFICACY AND SAFETY OF CANGRELOR WITH AND WITHOUT GLYCOPROTEIN IIB/IIIA INHIBITORS IN PATIENTS UNDERGOING PERCUTANEOUS CORONARY INTERVENTION: A POOLED ANALYSIS OF THE CHAMPION TRIALS

Cangrelor, an intravenous, reversible P2Y12 antagonist, was recently approved for use in patients undergoing percutaneous coronary intervention (PCI) in the US. We evaluated the efficacy and safety of cangrelor compared with clopidogrel in the subgroup who received glycoprotein IIb/IIIa inhibitors

IMPACT OF CANGRELOR OVERDOSING ON BLEEDING COMPLICATIONS IN PATIENTS UNDERGOING PERCUTANEOUS CORONARY INTERVENTION: INSIGHTS FROM THE CHAMPION TRIALS

Overdosing of parenteral antithrombotic drugs can increase the risk of bleeding. Cangrelor is a potent intravenous platelet P2Y12 receptor with rapid onset and offset of action. Compared with clopidogrel,cangrelor reduces periprocedural thrombotic complications in patients undergoing percutaneous