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TRILOGY-ACS: Prasugrel versus clopidodrel for patients with Unstable Angina/NSTEMI who are medically managed without revascularization

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Munich, Germany – 26 August 2012: The first trial to study the effect of platelet inhibition in patients with acute coronary syndromes managed medically without revascularisation has found no significant difference between prasugrel and clopidogrel in the prevention of death, myocardial infarction or stroke...
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Matthew Roe

List of Authors: Dr. Matthew Roe / United States
Co-authors: Dr. Paul Armstrong, Canada/Dr. Harvey White, New Zealand/Dr. Keith Fox, United Kingdom/Dr. Dorairaj Prabhakaran, India/Dr. Eileen Brown, United States/Dr. Yuliya Lokhnygina, United States/Dr. E. Magnus Ohman, United States


The optimal antiplatelet strategy for high-risk patients with unstable angina/non-ST-elevation myocardial infarction (UA/NSTEMI) who are managed medically without undergoing revascularization remains unclear.
In this international, double-blind, placebo-controlled, randomized trial we compared dual antiplatelet therapy with prasugrel + aspirin vs. clopidogrel + aspirin in 9,326 UA/NSTEMI patients who were medically managed without revascularization during the index hospitalization, and who had at least 1 of 4 high-risk criteria derived from the GRACE risk score (age > 60 years, prior myocardial infarction, diabetes mellitus, or prior coronary revascularization). Subjects were randomized within 10 days of hospital presentation, after the decision to utilize a medical management strategy without revascularization was confirmed. Patients < 75 years of age who were ≥ 60 kilograms of body weight were treated with a 10 mg maintenance dose of prasugrel vs. 75 mg of clopidogrel whereas those ≥ 75 years of age and/or < 60 kilograms of body weight were treated with a 5 mg maintenance dose of prasugrel vs. 75 mg of clopidogrel.  Low-dose aspirin (<100 mg) was strongly encouraged for all patients.  The primary efficacy composite endpoint is the time to first occurrence of cardiovascular death, MI, or stroke among patients of age < 75 years. The trial was designed as event-driven with power calculations indicating the need for at least 688 primary endpoints for a 20% effect size between therapies. If superiority of prasugrel vs. clopidogrel is shown in the group of patients < 75 years of age, then the treatment arms will be compared for all patients, including those patients < 75 years of age added together with those patients ≥ 75 years of age. Bleeding rates will be assessed by the GUSTO and TIMI criteria.
From June, 2008 through September, 2011, 9,326 patients (7,243 patients < 75 years of age and 2,083 patients ≥ 75 years of age) were enrolled in 53 countries at 968 sites.  The baseline characteristics of the 9,326 enrolled patients demonstrate the high-risk features of the overall study population including a median age of 66 years (25th, 75th percentiles: 59, 74), female sex in 39% of patients, weight < 60 kilograms in 15%, diabetes mellitus in 38%, prior MI in 43%, median creatinine clearance of 73 mL/min (54, 96), and median GRACE risk score of 121 (105,139).  The median follow-up time is expected to be 17-18 months. The last patient visit occurred on April 2, 2012 and the requisite number of primary endpoints has been accrued ensuring adequate power to address the study objectives.  Database lock is planned for early June, 2012 with final results available for an ESC 2012 presentation.
The results of the TRILOGY ACS trial will address the role of prasugrel (with a novel dosing regimen for the elderly and low body weight patients) for the long-term treatment of the high-risk population of UA/NSTEMI patients who are medically managed without revascularization.

Discussant | see Presenter abstract

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Raffaele De Caterina


Despite recommendations for moderate/high risk patients with non-ST elevation acute coronary syndromes (NSTE-ACS), about half such patients do not undergo early revascularization and are treated only medically. Such medically treated patients usually have more comorbidities, a higher risk of bleeding, and a worse global outcome than invasively treated patients, and here the benefit-risk balance of changing clopidogrel with a more potent platelet inhibitor is uncertain [1]. Prasugrel was tested against clopidogrel on top of aspirin in ACS – both ST elevation myocardial infarction (STEMI) and NSTE-ACS – in TRITON-TIMI 38 [2], but in a population of invasively treated patients. Therefore the role of prasugrel in managing non-invasively treated patients was unknown. In addition, there was a prohibitively high risk of bleeding in TRITON-TIMI 38 for patients ≥75 years of age [2], and therefore the assessment of a lower-dose regimen for prasugrel in these patients was warranted.
TRILOGY-ACS [3,4] was a randomized, double-blind, double-dummy, active-control, event-driven trial, with sample size (n=9326) and follow-up (median >14 months) adequate to detect a clinically significance difference (22% relative risk reduction) in the primary end point of cardiovascular (CV) death, myocardial infarction (MI) and stroke in subjects <75 years of age.
The study population was at moderate/high risk, including NSTEMI or unstable angina (UA) with >1 mm of ST depression plus 1 of 4 additional risk criteria: age ≥60 years, diabetes, prior MI, prior revascularization (percutaneous coronary interventions (PCI) or coronary artery bypass grafting (CABG)). There was a good geographical diversity (33.1% of patients from Central/Eastern Europe). 22.3% of pts ≥ 75 years of age [3,4]. Prasugrel maintenance dose was adjusted to 5 mg for patients ≥75 years (never previously tested)  and in pts <60 kg of body weight [3,4] (as done in TRITON-TIMI 38 [2]).
The primary efficacy end point (cardiovascular death, MI and stroke in patients <75 years) was not statistically different in the two randomized arms of the study. Statistical significance was also not achieved for other efficacy end points including CV death; MI; stroke; all-cause death; CV death+MI; recurrent hospitalization for UA; All-cause death, MI or stroke; and for the net clinical benefit end point, including major bleeding [4]. Therefore results do not support the trial main hypothesis.
None of the safety bleeding end points was statistically different between the two arms, including patient  >75 years of age (here indicating the safety success of the modified regimen adopted), but still numerically higher in the prasugrel group for moderate/minor bleeding (indicating the increased antiplatelet effect of prasugrel vs clopidogrel) [4].
There was an apparent separation of the curves after 12 months [4], which would be worthy of further investigation. No previous trial had tested a P2Y12 inhibitor with such a long follow-up (>14 months median).
These results should be put in the broader perspective of what is known with the other P2Y12 inhibitor so far tested also in this population, ticagrelor, as reported in a pre-specified sub-analysis of the PLATO Study [5]. Such a sub-analysis had been performed in a population half the size of TRILOGY-ACS, with a shorter follow-up (9.2 months median), and with a slightly lower risk profile (fewer women, fewer patients with hypertension, diabetes and previous MI). However in the PLATO sub-analysis ticagrelor use was associated with a significantly lower occurrence of the primary end point (vascular death, MI and stroke) and with less mortality by all causes (HR 0.75; 95% confidence intervals 0.61-0.93).
Thus, the two novel P2Y12 inhibitors so far tested in medically treated NSTE-ACS patients appear to provide different outcomes when compared with clopidogrel. Current ESC Guidelines on NSTE-ACS [6] state that ticagrelor is here recommended over clopidogrel for all patients at moderate-high risk of ischemic events regardless of the initial (invasive/non-invasive) treatment strategy; while prasugrel is recommended over clopidogrel only in patients in whom coronary anatomy is known and are proceeding to percutaneous coronary interventions. Such recommendations should not be changed as a result of TRILOGY-ACS.

1. Chan MY, Becker RC, Harrington RA, et al. Noninvasive, medical management for non-ST-elevation acute coronary syndromes. Am Heart J 2008;155:397-407.
2. Wiviott SD, Braunwald E, McCabe CH, et al. Prasugrel versus clopidogrel in patients with acute coronary syndromes. N Engl J Med 2007;357:2001-15.
3. Chin CT, Roe MT, Fox KA, et al. Study design and rationale of a comparison of prasugrel and clopidogrel in medically managed patients with unstable angina/non-ST-segment elevation myocardial infarction: the TaRgeted platelet Inhibition to cLarify the Optimal strateGy to medicallY manage Acute Coronary Syndromes (TRILOGY ACS) trial. Am Heart J 2010;160:16-22 e1.
4. Roe M, Armstrong P, Fox K, et al. Prasugrel versus clopidogrel for acute coronary syndrome patients managed without revascularization. N Engl J Med 2012;in press.
5. James SK, Roe MT, Cannon CP, et al. Ticagrelor versus clopidogrel in patients with acute coronary syndromes intended for non-invasive management: substudy from prospective randomised PLATelet inhibition and patient Outcomes (PLATO) trial. BMJ 2011;342:d3527.
6. Hamm CW, Bassand JP, Agewall S, et al. ESC Guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation: The Task Force for the management of acute coronary syndromes (ACS) in patients presenting without persistent ST-segment elevation of the European Society of Cardiology (ESC). Eur Heart J 2011;32:2999-3054.


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The content of this article reflects the personal opinion of the author/s and is not necessarily the official position of the European Society of Cardiology.