Ticagrelor: An investigational oral antiplatelet treatment for reduction of major adverse cardiac events in patients with acute coronary syndrome

Acute coronary syndromes (ACS) are the leading cause of mortality and one of the main reasons for hospital admissions in the developed nations. Due to high rates of mortality and reinfarction, ACS represent a major public health concern. Platelets play a central role in atherothrombosis, the main pathologic substrate in ACS. Sufficient inhibition of platelet aggregation is therefore one of the key targets in the treatment of ACS. Blockade of the P2Y12 subtype of adenosine diphosphate (ADP) receptor on platelet cell membranes has been established as a key mechanism of platelet inhibition. Clopidogrel, an ADP receptor antagonist and a second-generation thienopyridine, has been demonstrated to be of clinical benefit in patients with ACS when added to aspirin. A delayed onset of action due to two-step conversion to the active metabolite, irreversible binding to P2Y12 receptors, and broad interindividual variability in levels of platelet response are the main limitations of clopidogrel. Prasugrel, a novel third-generation thienopyridine, provides faster and stronger inhibition of platelet aggregation than clopigodrel. However, like the active metabolite of clopidogrel, prasugrel binds irreversibly to the P2Y12 ADP receptor site, causing inhibition of platelet aggregation for the life of the platelet. Although in a randomized, double-blind trial prasugrel demonstrated superiority for multiple cardiovascular endpoints compared with standard-dose clopidogrel, it was also associated with an increased bleeding risk, including fatal bleeding. This review discusses the optimal antiplatelet regimens for management of patients with ACS, with special focus on ticagrelor, the first oral agent in a new chemical class of nonthienopyridine antiplatelet agents termed cyclopentyltriazolo-pyrimidines. Faster and greater platelet inhibition than clopidogrel, quick recovery of platelet function, and high efficacy regardless of clopidogrel response status, are the obvious advantages of ticagrelor as compared with thienopyridines. The prospective, randomized Platelet Inhibition and Patient Outcomes trial has established the clinical utility, enhanced efficacy, and similar safety of ticagrelor as compared with clopidogrel in a wide range of patients with ACS managed with contemporary antithrombotic therapies and invasive strategies when indicated. Dyspnea, ventricular pauses ≥3 seconds, and elevation of serum creatinine and uric acid are the most common known adverse effects associated with ticagrelor, and require further comprehensive assessment

Contrast-induced nephropathy in interventional cardiology

Development of contrast-induced nephropathy (CIN), ie, a rise in serum creatinine by either ≥0.5 mg/dL or by ≥25% from baseline within the first 2–3 days after contrast administration, is strongly associated with both increased inhospital and late morbidity and mortality after invasive cardiac procedures. The prevention of CIN is critical if long-term outcomes are to be optimized after percutaneous coronary intervention. The prevalence of CIN in patients receiving contrast varies markedly (from <1% to 50%), depending on the presence of well characterized risk factors, the most important of which are baseline chronic renal insufficiency and diabetes mellitus. Other risk factors include advanced age, anemia, left ventricular dysfunction, dehydration, hypotension, renal transplant, low serum albumin, concomitant use of nephrotoxins, and the volume of contrast agent. The pathophysiology of CIN is likely to be multifactorial, including direct cytotoxicity, apoptosis, disturbances in intrarenal hemodynamics, and immune mechanisms. Few strategies have been shown to be effective to prevent CIN beyond hydration, the goal of which is to establish brisk diuresis prior to contrast administration, and to avoid hypotension. New strategies of controlled hydration and diuresis are promising. Studies are mixed on whether prophylactic oral N-acetylcysteine reduces the incidence of CIN, although its use is generally recommended, given its low cost and favorable side effect profile. Agents which have been shown to be ineffective or harmful, or for which data supporting routine use do not exist, include fenoldopam, theophylline, dopamine, calcium channel blockers, prostaglandin E1, atrial natriuretic peptide, statins, and angiotensin-converting enzyme inhibitors

A Randomized Comparison of the Endeavor Zotarolimus-Eluting Stent Versus the TAXUS Paclitaxel-Eluting Stent in De Novo Native Coronary Lesions 12-Month Outcomes From the ENDEAVOR IV Trial

ObjectivesThe ENDEAVOR IV (Randomized Comparison of Zotarolimus-Eluting and Paclitaxel-Eluting Stents in Patients with Coronary Artery Disease) trial evaluated the safety and efficacy of the zotarolimus-eluting stent (ZES) compared with the paclitaxel-eluting stent (PES).BackgroundFirst-generation drug-eluting stents have reduced angiographic and clinical restenosis, but long-term safety remains controversial. A second-generation drug-eluting stent, which delivers zotarolimus, a potent antiproliferative agent, via a biocompatible phosphorylcholine polymer on a cobalt alloy thin-strut stent has shown promising experimental and early clinical results.MethodsThis is a prospective, randomized (1:1), single-blind, controlled trial comparing outcomes of patients with single de novo coronary lesions treated with ZES or PES. The primary end point was noninferiority of 9-month target vessel failure defined as cardiac death, myocardial infarction, or target vessel revascularization.ResultsAmong a total of 1,548 patients assigned to ZES (n = 773) or PES (n = 775), at 9 months, ZES was noninferior to PES with rates of target vessel failure 6.6% versus 7.1%, respectively (pnoninferiority≤ 0.001). There were fewer periprocedural myocardial infarctions with ZES (0.5% vs. 2.2%; p = 0.007), whereas at 12 months, there were no significant differences between groups in rates of cardiac death, myocardial infarction, target vessel revascularization, or stent thrombosis. Although incidence of 8-month binary angiographic in-segment restenosis was higher in patients treated with ZES versus PES (15.3% vs. 10.4%; p = 0.284), rates of 12-month target lesion revascularization were similar (4.5% vs. 3.2%; p = 0.228), especially in patients without planned angiographic follow-up (3.6% vs. 3.2%; p = 0.756).ConclusionsThese findings demonstrate that ZES has similar clinical safety and efficacy compared with PES in simple and medium complexity single de novo coronary lesions. (ENDEAVOR IV Clinical Trial; NCT00217269