Faculty Bibliography

Since its advent over two decades ago, transradial access for cardiac catheterization and percutaneous intervention has evolved into a versatile and evidence-based approach for containing the risks of access-site bleeding and vascular complications without compromising the technical range or success associated with contemporary percutaneous coronary intervention (PCI). Early studies demonstrated reduced rates of vascular complications and access-site bleeding with radial-access catheterization but at the cost of increased access-site crossover and reduced procedural success. Contemporary data demonstrate that while the rates of major bleeding with femoral-access PCI in standard-risk cohorts have declined significantly over time, the transradial approach still retains significant advantages by way of reductions in vascular complications, length of stay, and enhanced patient comfort and patient preference over the femoral approach, while maintaining procedural success. Major adverse cardiovascular events and bleeding are lowest with the transradial approach when procedures are performed at high-volume radial centers, by experienced radial operators, or in the context of ST-segment elevation myocardial infarction. Choice of procedural anticoagulation appears to differentially impact access-site bleeding in transradial versus transfemoral PCI; however, non-access site bleeding remains a significant contributor to major bleeding in both groups. Despite abundant supporting data, adoption of transradial technique as the default strategy in cardiac catheterization in the United States has lagged behind many other countries. However, recent trends suggest that interest and adoption of the technique in the United States is growing at a brisker pace than previously observed.

DESCRIPTION/METHODS:Although approximately 85 million units of red blood cells (RBCs) are transfused annually worldwide, transfusion practices vary widely. The AABB (formerly, the American Association of Blood Banks) developed this guideline to provide clinical recommendations about hemoglobin concentration thresholds and other clinical variables that trigger RBC transfusions in hemodynamically stable adults and children. METHODS:These guidelines are based on a systematic review of randomized clinical trials evaluating transfusion thresholds. We performed a literature search from 1950 to February 2011 with no language restrictions. We examined the proportion of patients who received any RBC transfusion and the number of RBC units transfused to describe the effect of restrictive transfusion strategies on RBC use. To determine the clinical consequences of restrictive transfusion strategies, we examined overall mortality, nonfatal myocardial infarction, cardiac events, pulmonary edema, stroke, thromboembolism, renal failure, infection, hemorrhage, mental confusion, functional recovery, and length of hospital stay. RECOMMENDATION 1: The AABB recommends adhering to a restrictive transfusion strategy (7 to 8 g/dL) in hospitalized, stable patients (Grade: strong recommendation; high-quality evidence). RECOMMENDATION 2: The AABB suggests adhering to a restrictive strategy in hospitalized patients with preexisting cardiovascular disease and considering transfusion for patients with symptoms or a hemoglobin level of 8 g/dL or less (Grade: weak recommendation; moderate-quality evidence). RECOMMENDATION 3: The AABB cannot recommend for or against a liberal or restrictive transfusion threshold for hospitalized, hemodynamically stable patients with the acute coronary syndrome (Grade: uncertain recommendation; very low-quality evidence). RECOMMENDATION 4: The AABB suggests that transfusion decisions be influenced by symptoms as well as hemoglobin concentration (Grade: weak recommendation; low-quality evidence).

BACKGROUND:We evaluated the safety, efficacy, and tolerability of elinogrel, a competitive, reversible intravenous and oral P2Y(12) inhibitor that does not require metabolic activation, in patients undergoing nonurgent percutaneous coronary intervention. METHODS AND RESULTS/RESULTS:In a randomized, double-blind, dose-ranging phase 2b trial, 652 patients received either 300 or 600 mg of clopidogrel pre-percutaneous coronary intervention followed by 75 mg daily or 80 or 120 mg of IV elinogrel followed by 50, 100, or 150 mg oral elinogrel twice daily. Numerous exploratory safety and efficacy end points were assessed and, as such, had no prespecified primary end point, and the study was not powered to conclusively evaluate its objectives. Thrombolysis in myocardial infarction combined bleeding was increased with elinogrel (hazard ratio, 1.98; 95% confidence interval, 1.10 to 3.57), related largely to increased bleeding requiring medical attention (elinogrel 47/408 [11.5%] versus clopidogrel 13/208 [6.3%]) and occurring primarily at the percutaneous coronary intervention access site. Efficacy end points and postprocedure cardiac enzyme were similar, but there was a nonsignificant higher frequency of periprocedural myocardial infarctions in the elinogrel arms (OR, 1.59; 95% confidence interval, 0.79 to 3.48). There was an increased incidence of dyspnea (elinogrel 50/408 [12.3%] versus clopidogrel 8/208 [3.8%]) and transaminase elevation (alanine transferase/aspartate transferase >3× the upper limit of normal; elinogrel 18/408 [4.4%] versus clopidogrel 2/208 [1.0%]) in the elinogrel arms, but there were no cases of heart block, bradycardia, hypotension, or liver failure. CONCLUSIONS:In patients undergoing nonurgent percutaneous coronary intervention and in comparison with clopidogrel, intravenous and oral elinogrel therapy did not significantly increase thrombolysis in myocardial infarction major or minor bleeding, although bleeding requiring medical attention was more common. The significance of these findings will need to be more definitively determined in future Phase 3 studies. CLINICAL TRIAL REGISTRATION/BACKGROUND:URL: http://www.clinicaltrials.gov. Unique identifier: NCT00751231.

BACKGROUND:Elinogrel is the only selective, competitive and reversible platelet P2Y(12) inhibitor available in both intravenous (IV) and oral formulations. METHODS AND RESULTS/RESULTS:This substudy of the Intravenous and Oral Administration of Elinogrel to Evaluate Tolerability and Efficacy in Nonurgent Percutaneous Coronary Intervention patients (INNOVATE-PCI) trial evaluated the pharmacokinetic and pharmacodynamic effects of two dosing regimens of IV followed by oral elinogrel (120 mg IV plus 100 mg oral twice daily; 120 mg IV plus 150 mg oral twice daily) versus standard clopidogrel therapy (300-600 mg oral loading dose plus 75 mg oral maintenance dose) in 56 patients undergoing nonurgent PCI. At time of randomization, 71.4% (40/56) of patients were using maintenance clopidogrel therapy. In the acute phase, an IV bolus of elinogrel achieved more rapid and potent antiplatelet effects compared with clopidogrel, which were sustained during the transition from the IV to the oral formulation in the first 24 hours of the peri-PCI period. During chronic therapy, elinogrel achieved similar levels of platelet reactivity compared with clopidogrel before the next oral dose and, although platelet reactivity was lower with elinogrel up to 6 hours after daily oral maintenance dosing, these differences were not statistically significant. These pharmacodynamic effects matched the pharmacokinetic profile of elinogrel. There were no differences in pharmacodynamic and pharmacokinetic effects between the two elinogrel dosing regimens. CONCLUSIONS:Compared with clopidogrel, the combination of IV and oral elinogrel achieves more rapid and enhanced antiplatelet effects that were sustained through the transition to oral elinogrel in the peri-PCI period, but these were not significant during chronic dosing in this pilot investigation. CLINICAL TRIAL REGISTRATION/BACKGROUND:URL: http://www.clinicaltrials.gov. Unique identifier: NCT00751231.

OBJECTIVES/OBJECTIVE:The purpose of this study was to examine temporal trends in post-percutaneous coronary intervention (PCI) bleeding among patients with elective PCI, unstable angina (UA)/non-ST-segment elevation myocardial infarction (NSTEMI), and ST-segment elevation myocardial infarction (STEMI). BACKGROUND:The impact of bleeding avoidance strategies on post-PCI bleeding rates over time is unknown. METHODS:Using the CathPCI Registry, we examined temporal trends in post-PCI bleeding from 2005 to 2009 among patients with elective PCI (n = 599,524), UA/NSTEMI (n = 836,103), and STEMI (n = 267,632). We quantified the linear time trend in bleeding using 3 sequential logistic regression models: 1) clinical factors; 2) clinical + vascular access strategies (femoral vs. radial, use of closure devices); and 3) clinical, vascular strategies + antithrombotic treatments (anticoagulant ± glycoprotein IIb/IIIa inhibitor [GPI]). Changes in the odds ratio for time trend in bleeding were compared using bootstrapping and converted to risk ratio. RESULTS:An approximate 20% reduction in post-PCI bleeding was seen (elective PCI: 1.4% to 1.1%; UA/NSTEMI: 2.3% to 1.8; STEMI: 4.9% to 4.5%). Radial approach remained low (<3%), and closure device use increased marginally from 44% to 49%. Bivalirudin use increased (17% to 30%), whereas any heparin + GPI decreased (41% to 28%). There was a significant 6% to 8% per year reduction in annual bleeding risk in UA/NSTEMI and elective PCI, but not in STEMI. Antithrombotic strategies were associated with roughly half of the reduction in annual bleeding risk: change in risk ratio from 7.5% to 4% for elective PCI, and 5.7% to 2.8% for UA/NSTEMI (both p <0.001). CONCLUSIONS:The nearly 20% reduction in post-PCI bleeding over time was largely due to temporal changes in antithrombotic strategies. Further reductions in bleeding complications may be possible as bleeding avoidance strategies evolve, especially in STEMI.

High residual platelet reactivity (HRPR) on clopidogrel is a predictor of recurrent ischemic events in patients undergoing percutaneous coronary interventions (PCI). Significant intraindividual variability in platelet aggregation on repeat testing has been reported. To understand factors contributing to the variability in platelet aggregation testing, we examined clinical and laboratory elements linked to HRPR in 255 consecutive patients tested ≥12 hours after PCI using light transmission aggregometry (LTA) in response to adenosine diphosphate 5 μmol/L and VerifyNow P2Y12 assay (VNP2Y12; Accumetrics). HRPR was defined as >46% residual aggregation for LTA and >236 P2Y12 response units (PRUs) for VNP2Y12. On multivariate analysis the only variable independently associated with HRPR with both LTA and VNP2Y12 was laboratory-defined anemia. Prevalences of HRPR by LTA were 34.3% in anemic patients, 15.6% in patients with normal hemoglobin levels, and 59.8% versus 25.9% by VNP2Y12 (p <0.005 for the 2 comparisons). In a subgroup of 50 patients, testing was done before and after the clopidogrel loading dose. At baseline there were no differences in platelet aggregation with either assay; however, absolute decrease in reactivity after the clopidogrel load was significantly less in anemic patients compared to patients with normal hemoglobin (change in residual aggregation by LTA 15.8 ± 5.8% vs 28.8 ± 3.2%, p <0.05; change in PRU by VNP2Y12 56.5 ± 35.5 vs 145.0 ± 14.2 PRUs, p <0.05, respectively). In conclusion, anemia is an important contributor to apparent HRPR on clopidogrel and may explain some of the intraindividual variability of platelet aggregation testing.

BACKGROUND:Prior studies have suggested that blacks with acute ST-segment-elevation myocardial infarction have increased bleeding risks with fibrinolysis relative to whites, yet these data were quite limited. Additionally, it is unknown whether there are racial differences in bleeding risks among patients with ST-segment-elevation myocardial infarction receiving primary percutaneous coronary intervention. METHODS AND RESULTS/RESULTS:We evaluated data on blacks and whites with ST-segment-elevation myocardial infarction treated with either fibrinolysis or primary percutaneous coronary intervention from the National Registry of Myocardial Infarction (NRMI)-4 and 5 participating centers between July 2000 and December 2006. We compared differences between the 2 groups in rates of in-hospital major bleeding and mortality, adjusted with logistic regression analyses. In fibrinolytic-treated patients with ST-segment-elevation myocardial infarction, the bleeding rates were higher among blacks (n=2283) than whites (n=42 243; 10.9% versus 10.3%; adjusted odds ratio, 1.21; 95% confidence interval, 1.02-1.43). Similarly, in patients receiving primary percutaneous coronary intervention, the bleeding rates were higher in blacks (n=2826) than in whites (n=46 332; 10.3% versus 7.8%; adjusted odds ratio, 1.33; 95% confidence interval, 1.13-1.56). Bleeding was associated with higher risk of death in both ethnic groups. However, there was no overall racial difference in in-hospital mortality among those with bleeding or without bleeding treated with either fibrinolysis or primary percutaneous coronary intervention. CONCLUSIONS:Blacks with ST-segment-elevation myocardial infarction treated with either fibrinolysis or primary percutaneous coronary intervention had a higher risk of bleeding events than their white counterparts. Bleeding was associated with a similar increased risk of death in both ethnic groups treated by either reperfusion strategy.

BACKGROUND:Despite lower risks of access site-related complications with transradial approach (TRA), its clinical benefit for percutaneous coronary intervention (PCI) is uncertain. We conducted a systematic review and meta-analysis of clinical studies comparing TRA and transfemoral approach (TFA) for PCI. METHODS:Randomized trials and observational studies (1993-2011) comparing TRA with TFA for PCI with reports of ischemic and bleeding outcomes were included. Crude and adjusted (for age and sex) odds ratios (OR) were estimated by a hierarchical Bayesian random-effects model with prespecified stratification for observational and randomized designs. The primary outcomes were rates of death, combined incidence of death or myocardial infarction, bleeding, and transfusions, early (≤ 30 days) and late after PCI. RESULTS:We collected data from 76 studies (15 randomized, 61 observational) involving a total of 761,919 patients. Compared with TFA, TRA was associated with a 78% reduction in bleeding (OR 0.22, 95% credible interval [CrI] 0.16-0.29) and 80% in transfusions (OR 0.20, 95% CrI 0.11-0.32). These findings were consistent in both randomized and observational studies. Early after PCI, there was a 44% reduction of mortality with TRA (OR 0.56, 95% CrI 0.45-0.67), although the effect was mainly due to observational studies (OR 0.52, 95% CrI 0.40-0.63, adjusted OR 0.49 [95% CrI 0.37-0.60]), with an OR of 0.80 (95% CrI 0.49-1.23) in randomized trials. CONCLUSION/CONCLUSIONS:Our results combining observational and randomized studies show that PCI performed by TRA is associated with substantially less risks of bleeding and transfusions compared with TFA. Benefit on the incidence of death or combined death or myocardial infarction is found in observational studies but remains inconclusive in randomized trials.