Faculty Bibliography

BACKGROUND:Previous data on bleeding after percutaneous coronary intervention (PCI) have been obtained primarily from randomized trials that focused on in-hospital bleeding. The incidence of late bleeding after PCI, its independent predictors, and its prognostic importance in clinical practice has not been fully addressed. METHODS AND RESULTS/RESULTS:We evaluated 22 798 patients aged >65 years who underwent PCI from December 1, 2003, to March 31, 2007, in Ontario, Canada. Cox proportional hazard models were used to determine factors associated with late bleeding, which was defined as hospitalization for bleeding after discharge from the index PCI, and to estimate risk of death or myocardial infarction associated with late bleeding. We found that 2.5% of patients were hospitalized for bleeding in the year after PCI, with 56% of bleeding episodes due to gastrointestinal bleed. The most significant predictor of late bleeding was warfarin use after PCI (hazard ratio [HR], 3.12). Other significant predictors included age (HR, 1.41 per 10 years), male sex (HR, 1.24), cancer (HR, 1.80), previous bleeding (HR, 2.42), chronic kidney disease (HR, 1.93), and nonsteroidal antiinflammatory drug use (HR, 1.73). After adjusting for baseline covariates, hospitalization for a bleeding episode was associated with a significantly increased 1-year hazard of death or myocardial infarction (HR, 2.39; 95% CI, 1.93 to 2.97) and death (HR, 3.38; 95% CI, 2.60 to 4.40). CONCLUSIONS:Hospitalization for late bleeding after PCI is associated with substantially increased risk of death and myocardial infarction. The use of triple therapy (i.e., aspirin, thienopyridine, and warfarin) is associated with the highest risk of late bleeding.

BACKGROUND:Factor Xa and factor IIa (thrombin) play roles in thrombotic complications after percutaneous coronary intervention. M118 is a novel low-molecular-weight heparin that has been rationally designed to capture the desired attributes of unfractionated heparin (UFH) and low-molecular-weight heparin: Potent activity against factor Xa and IIa, predictable pharmacokinetics after both intravenous and subcutaneous administration, ability to be monitored by use of point-of-care coagulation assays, and reversibility with protamine sulfate. We performed a phase 2 randomized trial to evaluate the safety and feasibility of M118 in the setting of elective percutaneous coronary intervention. METHODS AND RESULTS/RESULTS:Overall, 503 patients undergoing elective percutaneous coronary intervention at 43 centers in the United States and Canada were randomized in an open-label fashion to 1 of 4 arms: UFH 70 U/kg, M118 50 IU/kg IV, M118 75 IU/kg IV, or M118 100 IU/kg IV. The primary outcome was the composite of death, myocardial infarction, repeat revascularization, stroke, thrombocytopenia, catheter thrombus, bailout use of glycoprotein IIb/IIIa inhibitor, or any bleeding through 30 days. The primary end point occurred in 31.1% of patients randomized to UFH and in 22.7%, 28.3%, and 30.1% of patients randomized to M118 50, 75, and 100 IU/kg, respectively. The primary analysis comparing the rates of the primary end points between the pooled M118 groups versus UFH demonstrated that M118 was noninferior to UFH at preventing percutaneous coronary intervention-related complications (28.4% pooled M118 arms versus 31.1% UFH). The adverse event profiles of M118 and UFH were comparable. CONCLUSIONS:This phase 2 randomized trial demonstrates that M118 is well tolerated and feasible to use as an anticoagulant in patients undergoing elective percutaneous coronary intervention and forms the basis for further investigation of this agent in ischemic heart disease. CLINICAL TRIAL REGISTRATION/BACKGROUND:URL: http://www.clinicaltrials.gov. Unique identifier: NCT00543400.

OBJECTIVES/OBJECTIVE:We sought to create contemporary models for predicting mortality risk following percutaneous coronary intervention (PCI). BACKGROUND:There is a need to identify PCI risk factors and accurately quantify procedural risks to facilitate comparative effectiveness research, provider comparisons, and informed patient decision making. METHODS:Data from 181,775 procedures performed from January 2004 to March 2006 were used to develop risk models based on pre-procedural and/or angiographic factors using logistic regression. These models were independently evaluated in 2 validation cohorts: contemporary (n = 121,183, January 2004 to March 2006) and prospective (n = 285,440, March 2006 to March 2007). RESULTS:Overall, PCI in-hospital mortality was 1.27%, ranging from 0.65% in elective PCI to 4.81% in ST-segment elevation myocardial infarction patients. Multiple pre-procedural clinical factors were significantly associated with in-hospital mortality. Angiographic variables provided only modest incremental information to pre-procedural risk assessments. The overall National Cardiovascular Data Registry (NCDR) model, as well as a simplified NCDR risk score (based on 8 key pre-procedure factors), had excellent discrimination (c-index: 0.93 and 0.91, respectively). Discrimination and calibration of both risk tools were retained among specific patient subgroups, in the validation samples, and when used to estimate 30-day mortality rates among Medicare patients. CONCLUSIONS:Risks for early mortality following PCI can be accurately predicted in contemporary practice. Incorporation of such risk tools should facilitate research, clinical decisions, and policy applications.

Coronary artery plaque rupture results in platelet adhesion and activation, the release of adenosine diphosphate (ADP), thromboxane A(2), and the generation of thrombin. These factors propagate further platelet activation through a positive feedback mechanism, resulting in the formation of a platelet plug. The treatment of patients with ACS is centered upon the prompt initiation of both antiplatelet and anticoagulant agents. The widespread use of antiplatelet and anticoagulant agents has resulted in a significant reduction in morbidity and mortality but has also increased the risk for bleeding complications. Female gender, advanced age, low body mass index (BMI), low creatinine clearance, and the use of percutaneous coronary intervention have been consistently shown to be risk factors for bleeding. While bleeding was thought to be a necessary side effect and of little clinical significance in the past, it is now clear that bleeding is an independent predictor of adverse ischemic events and mortality. The mechanisms underlying this relationship are not yet fully elucidated and are likely multifactorial (direct effects of bleeding, increased incidence of blood transfusions, less use of antiplatelet agents in both the short and long term). Current treatment guidelines for the use of antithrombotic therapy recommend utilization of evidence-based therapies using clinical strategies shown to minimize the risk of bleeding should when possible. Novel therapies that minimize bleeding risk while providing protection against thrombotic events are needed and may improve outcomes among patients with ACS. Multiple platelet activation pathways and the coagulation cascade regulate hemostasis and thrombosis. Current antiplatelet and anticoagulant therapies for acute coronary syndromes (ACS) act on distinct sites in the pathways for platelet activation and coagulation. While these therapies are effective in reducing the morbidity and mortality associated with ACS, they are associated with a clinically significant increase in the risk of bleeding events. Novel therapies that minimize bleeding risk while providing protection against thrombotic events may improve outcomes in patients with ACS.

Periprocedural bleeding complications after percutaneous coronary intervention (PCI) are associated with increased short- and long-term morbidity and mortality. Although clinical trials have primarily assessed pharmacological strategies for reducing bleeding risk, there is a mounting body of evidence suggesting that adoption of a transradial rather than a transfemoral approach to PCI may permit greater reductions in bleeding risk than have been achieved with pharmacological strategies alone. However, despite a long history of use, a lack of widespread uptake by physicians coupled with the technological limitations of available devices has in the past confined transradial PCI to the status of a niche procedure, and many operators lack experience in this technique. In this review, we examine the history of the transradial approach to PCI and discuss some of the circumstances that have hitherto limited its appeal. We then review the current state of the peer-reviewed literature supporting its use and summarize the unresolved issues affecting broader application of this technique, including lack of operator familiarity and an insufficient evidence base for guiding practice. Finally, we describe potential directions for future investigation in the transradial realm.

BACKGROUND:Although bivalirudin compared with unfractionated heparin with glycoprotein IIb/IIIa inhibitors reduces bleeding and hospitalization costs in patients undergoing percutaneous coronary intervention (PCI), little is known about the economic impact of bivalirudin versus heparin alone and at what threshold of procedural bleeding risk bivalirudin would be considered cost-effective. METHODS AND RESULTS/RESULTS:A validated model was used to predict risk of major bleeding for 81,628 National Cardiovascular Data Registry (NCDR) CathPCI Registry patients from 2004 to 2006 who received unfractionated heparin only. Costs were derived from multiple sources including wholesale acquisition costs (for drugs) and single-center data (for PCI-related complications). Based on ISAR-REACT 3, we assumed that bivalirudin would reduce the risk of major bleeding by 33% compared with unfractionated heparin alone. A Markov model was used to estimate lost life expectancy associated with a major bleed. Major bleeding was predicted to occur in 2.2% of patients. Bivalirudin for all patients was estimated to increase costs by $571 per patient, yielding cost-effectiveness ratios of $287,473 per bleeding event averted and $1,173,360 per quality-adjusted life-year gained. Bivalirudin was cost saving for patients with a predicted bleeding risk >20% (0.16% of CathPCI population). At willingness-to-pay thresholds of $50K and $100K per quality-adjusted life-year gained, bivalirudin was cost-effective for patients with a bleeding risk > or = 8% (2.5% patients) and > or = 5% (7.9% patients), respectively. CONCLUSIONS:This decision-analytic modeling study demonstrates that for patients undergoing PCI, substitution of bivalirudin for unfractionated heparin monotherapy is projected to increase costs for virtually all patients and would be considered cost-effective for only a minority of patients with a high bleeding risk. From a policy standpoint, studies such as this, aimed at identifying the appropriate risk threshold for initiating treatment, may help in the development of informed guidelines for the use of expensive therapies.

Thrombocytopenia is associated with increased patient risk. However, the costs of this complication are not well defined. This study assessed the impact of thrombocytopenia on in-hospital costs using results from CATCH, an observational study that examined 1988 consecutive patients receiving prolonged heparin therapy (> or =96 h). Thrombocytopenia was defined as: (group 1) an absolute reduction in platelet count to <150 x 10(9)/L; (group 2) a relative reduction in platelet count of >50% from admission levels; or (group 3) both criteria. We found that the development of thrombocytopenia was associated with significantly higher total in-hospital costs for all groups: (group 1) (difference, $8,222; 95% CI, $5,020-$11,425; P<.001); (group 2) (difference, $15,429; 95% CI, $7,472-$23,385; P<.001); and (group 3) (difference, $27,077; 95% CI, $22,901-$31,252; P<.001). However, in our adjusted model, longer lengths-of-stay and greater use of blood transfusions accounted for most incremental in-hospital cost differences.