George Hahalis

Randomized Assessment of Ticagrelor Versus Prasugrel Antiplatelet Effects in Patients with ST-Segment–Elevation Myocardial Infarction

Background—Ticagrelor and prasugrel provide stronger platelet inhibition compared with clopidogrel. Direct pharmacodynamic comparison between them has not yet been reported in ST-segment–elevation myocardial infarction patients. Methods and Results—In a prospective, single-center, single-blind study, 55 out of 117 (47%) screened consecutive ST-segment–elevation myocardial infarction patients undergoing primary percutaneous coronary intervention were randomized to either ticagrelor 180 mg loading followed by 90 mg bid, or prasugrel 60 mg loading followed by 10 mg od for 5 days. Platelet reactivity (PR) was assessed with the VerifyNow P2Y12 function assay and the Multiplate Analyzer at 0, 1, 2, 6, 24 hours, and 5 days postrandomization. The primary end point, PR with VerifyNow at hour 1, did not differ significantly between patients randomized to ticagrelor versus prasugrel (257.3 P2Y12 reaction unit [PRU], 95% CI 230.8–283.8 versus 231.3 PRU, 95% CI 205.3–257.4; P=0.2). PR did not differ at 2, 6, and 24 hours, although at day 5 it was lower with ticagrelor than prasugrel (25.6 PRU, 95% CI 12.3–38.9 versus 50.3 PRU, 95% CI 36.4–64.1; P=0.01). At hour 2, high on-treatment PR rates (cutoff 208 PRU) were 46.2% and 34.6% for ticagrelor and prasugrel, respectively, decreased significantly thereafter, whereas did not differ significantly between the 2 agents at all the time points of the study. Conclusions—In patients with ST-segment–elevation myocardial infarction undergoing primary percutaneous coronary intervention, both ticagrelor and prasugrel exhibit an initial delay in the onset of their antiplatelet action. Ticagrelor did not appear superior to prasugrel in reducing PR during the first 24 hours of ST-segment–elevation myocardial infarction. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT01463163.

Ticagrelor Versus Prasugrel in Acute Coronary Syndrome Patients With High On-Clopidogrel Platelet Reactivity Following Percutaneous Coronary Intervention: A Pharmacodynamic Study

OBJECTIVES The study aimed to compare the antiplatelet action of ticagrelor with prasugrel in acute coronary syndrome (ACS) patients with high on-treatment platelet reactivity (HTPR) while on clopidogrel after percutaneous coronary intervention (PCI). BACKGROUND Newer P2Y12 inhibitors like prasugrel and ticagrelor provide stronger platelet inhibition compared with clopidogrel. Both agents are efficacious in patients with HTPR while on clopidogrel, but direct comparison between them has not yet been reported. METHODS In a prospective, single-center, single-blind study, 44 (of 139 screened, 31.7%) ACS patients with HTPR while on clopidogrel 24 h post-PCI were randomized to either ticagrelor 90 mg twice daily or prasugrel 10 mg once daily for 15 days with a crossover directly to the alternate treatment for another 15 days. HTPR was defined as platelet reactivity units (PRU) ≥ 235 as assessed by the VerifyNow P2Y12 function assay. RESULTS The primary endpoint of platelet reactivity at the end of the 2 treatment periods was lower for ticagrelor (32.9 PRU, 95% confidence interval [CI]: 18.7 to 47.2) compared with prasugrel (101.3 PRU, 95% CI: 86.8 to 115.7) with a least squares mean difference of -68.3 PRU (95% CI: -88.6 to -48.1; p < 0.001). The secondary endpoint of HTPR rate was 0% for ticagrelor and 2.4% for prasugrel (1 of 42, p = 0.5). No patient exhibited a major bleeding event at either treatment group. CONCLUSIONS In patients with ACS exhibiting HTPR while on clopidogrel 24 h post-PCI, ticagrelor produces a significantly higher platelet inhibition compared with prasugrel. (Ticagrelor Versus Prasugrel in Acute Coronary Syndromes After Percutaneous Coronary Intervention; NCT01360437).

Prasugrel overcomes high on-clopidogrel platelet reactivity post-stenting more effectively than high-dose (150-mg) clopidogrel: the importance of CYP2C19*2 genotyping.

OBJECTIVES The primary aim of the study was to determine the antiplatelet effects of prasugrel versus high-dose clopidogrel in patients with high on-treatment platelet reactivity (HTPR) after percutaneous coronary intervention (PCI) and, secondarily, their relation to cytochrome (CYP) 2C19*2 carriage. BACKGROUND High on-treatment platelet reactivity after clopidogrel administration after PCI is linked to the loss-of-function CYP2C19*2 allele and accompanied by an increased risk of adverse events. METHODS We performed a prospective, randomized, single-blind, crossover study of platelet inhibition by prasugrel 10 mg/day versus high-dose 150 mg/day clopidogrel in 71 (of 210 screened; 33.8%) post-PCI patients with HTPR. Platelet function was assessed by the VerifyNow assay (Accumetrics, San Diego, California), and real-time polymerase chain reaction genotyping was performed for CYP2C19*2 carriage. RESULTS The primary endpoint of platelet reactivity (measured in platelet reactivity units) at the end of the 2 treatment periods was lower after prasugrel compared with clopidogrel (least-squares estimates 129.4, 95% confidence interval [CI]: 111.1 to 147.7 versus 201.7, 95% CI: 183.2 to 220.2; p < 0.001). The least-squares mean difference between the 2 treatments was -122.9 (95% CI: -166.7 to -79.2, p < 0.001), and -47.5 (95% CI: -79.5 to -15.4, p = 0.004), in carriers and noncarriers of at least 1 mutant allele, respectively. The HTPR rates were lower for prasugrel than for clopidogrel, in all patients (7.5% vs. 35.8%, p < 0.001), in carriers (5.3% vs. 47.4%, p = 0.007), and in noncarriers (8.8% vs. 29.4%, p = 0.005), respectively. CONCLUSIONS In patients with HTPR after PCI, prasugrel is more effective compared with high clopidogrel in reducing platelet reactivity, particularly in CYP2C19*2 carriers. Genotyping guidance might be helpful only in case an increased clopidogrel maintenance dose is considered. (Prasugrel Versus High Dose Clopidogrel in Clopidogrel Resistant Patients Post Percutaneous Coronary Intervention (PCI); NCT01109784).

Renoprotective effect of remote ischemic post-conditioning by intermittent balloon inflations in patients undergoing percutaneous coronary intervention.

OBJECTIVES The aim of the present study was to assess the efficacy of remote ischemic post-conditioning (RIPC) by repeated intermittent balloon inflations in preventing acute kidney injury (AKI) in patients with a non-ST-segment elevation myocardial infarction undergoing percutaneous coronary intervention (PCI). BACKGROUND AKI complicating PCI is associated with increased morbidity and mortality. Remote ischemic preconditioning, using cycles of upper limb ischemia-reperfusion as a conditioning stimulus, has been recently shown to prevent AKI in patients undergoing elective coronary angiography. METHODS Eligible patients were randomized to receive RIPC by cycles of inflation and deflation of the stent balloon during PCI or a sham procedure (control patients). The primary endpoint was AKI, defined as an increase of ≥ 0.5 mg/dl or ≥ 25% in serum creatinine within 96 h from PCI. The 30-day rate of death or re-hospitalization for any cause was one of the secondary endpoints. RESULTS A total of 225 patients were included (median age, 68 years; 36% female). The AKI rate in the RIPC group was 12.4% versus 29.5% in the control group (p = 0.002; odds ratio: 0.34; 95% confidence interval: 0.16 to 0.71). The number needed to treat to avoid 1 case of AKI was 6 (95% confidence interval: 3.6 to 15.2). The 30-day rate of death or re-hospitalization for any cause was 22.3% in the control group versus 12.4% in RIPC patients (p = 0.05). CONCLUSIONS RIPC by serial balloon inflations and deflations during PCI was found to confer protection against AKI in patients with a non-ST-segment elevation myocardial infarction undergoing PCI. The reduction in the rate of AKI translated into a clear trend (of borderline significance) toward better 30-day clinical outcome.

Prasugrel overcomes high on-clopidogrel platelet reactivity in chronic coronary artery disease patients more effectively than high dose (150 mg) clopidogrel

BACKGROUND High on-treatment platelet reactivity (HTPR) is present in a substantial percentage of patients on chronic clopidogrel treatment and may have prognostic implications. Strategies to optimize platelet inhibition in such patients are not clear. METHODS We performed a prospective, single-center, single-blinded, investigator-initiated randomized, crossover study of platelet inhibition by prasugrel 10 mg/day versus high-dose 150 mg/day clopidogrel, with a 14 day treatment period, in 31 patients with HTPR (out of 99 screened, 31.3%) while on chronic (≥ 12 months) treatment with clopidogrel. All patients had stable coronary artery disease and 87.1% of them had a prior percutaneous coronary intervention. Platelet reactivity (PR) was assessed by the VerifyNow assay measured in platelet reactivity units (PRU). RESULTS The primary end point of PR at the end of the two treatment periods was lower in patients receiving prasugrel compared with high dose clopidogrel ( least squares estimate 148.1, 95% CI 127.1-169.2 and 219.8, 95% CI 198.6-240.9 respectively, P < .001). The secondary end point of HTPR rate was lower for prasugrel compared with clopidogrel, 11.5% vs 46.3%, P = .003. CONCLUSIONS Prasugrel appears more effective than double clopidogrel in inhibiting PR in patients with HTPR following chronic clopidogrel treatment.

Colchicine Treatment for the Prevention of Bare-Metal Stent Restenosis in Diabetic Patients

OBJECTIVES This study sought to test the hypothesis that colchicine treatment after percutaneous coronary intervention (PCI) can lead to a decrease in in-stent restenosis (ISR). BACKGROUND ISR rates are particularly high in certain patient subsets, including diabetic patients, especially when a bare-metal stent (BMS) is used. Pharmacological interventions to decrease ISR could be of clinical relevance. METHODS Diabetic patients with contraindication to a drug-eluting stent, undergoing PCI with a BMS, were randomized to receive colchicine 0.5 mg twice daily or placebo for 6 months. Restenosis and neointima formation were studied with angiography and intravascular ultrasound 6 months after the index PCI. RESULTS A total of 196 patients (63.6 ± 7.0 years of age, 128 male) were available for analysis. The angiographic ISR rate was 16% in the colchicine group and 33% in the control group (p = 0.007; odds ratio: 0.38, 95% confidence interval: 0.18 to 0.79). The number needed to treat to avoid 1 case of angiographic ISR was 6 (95% confidence interval: 3.4 to 18.7). The results were similar for IVUS-defined ISR (odds ratio: 0.42; 95% confidence interval: 0.22 to 0.81; number needed to treat = 5). Lumen area loss was 1.6 mm(2) (interquartile range: 1.0 to 2.9 mm(2)) in colchicine-treated patients and 2.9 mm(2) (interquartile range: 1.4 to 4.8 mm(2)) in the control group (p = 0.002). Treatment-related adverse events were largely limited to gastrointestinal symptoms. CONCLUSIONS Colchicine is associated with less neointimal hyperplasia and a decreased ISR rate when administered to diabetic patients after PCI with a BMS. This observation may prove useful in patients undergoing PCI in whom implantation of a drug-eluting stent is contraindicated or undesirable.

Acute anterior myocardial infarction after multiple bee stings. A case of Kounis syndrome

A 58-year-old man with no history of cardiac diseases or cardiovascular risk factors was stung by honeybees. Soon after, he gradually developed signs of an allergic reaction followed by severe retrosternal pain. Electrocardiographic, echocardiographic evidence and positive biochemical markers were consistent with an acute anterolateral myocardial infarction. Coronary arteriography showed a left anterior descending artery thrombotic lesion. This is a case of Kounis syndrome, which is the concurrence of acute coronary syndromes with conditions associated with mast cell activation including allergic or hypersensitivity reactions as well as anaphylactic or anaphylactoid insults. The clinical implications and pathophysiology of this dangerous association are discussed.

Double Versus Standard Loading Dose of Ticagrelor : Onset of Antiplatelet Action in Patients With STEMI Undergoing Primary PCI

To the Editor: Early and strong platelet inhibition is highly desirable in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI). Ticagrelor, which has direct action on the P2Y12 receptor and no need for previous metabolic

Kounis syndrome: a manifestation of drug-eluting stent thrombosis associated with allergic reaction to contrast material.

Stent components acting as potential antigens and promoting intracoronary mast cell activation can lead to catastrophic intrastent thrombosis. Patients with drug-eluting stent (DES) implantation are prone to hypersensitivity reactions from five potential antigens namely, nickel strut, polymer coating, eluted drug, as well as, concomitant drugs clopidogrel and aspirin. These events may be more common than suspected because it is hard to document them, unless they become systemic, in which case they manifest themselves as the Kounis syndrome characterized by the concurrence of acute coronary events with hypersensitivity reactions. This report concerns of a patient with implanted DES who developed an acute myocardial infarction in the stent area following an allergic reaction to contrast material.

Differential Effect of Ticagrelor Versus Prasugrel on Coronary Blood Flow Velocity in Patients With Non–ST-Elevation Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention: An Exploratory Study

Background—Prasugrel and ticagrelor provide a superior anti-ischemic action than clopidogrel, with some of ticagrelor’s benefits possibly attributed to adenosine-mediated mechanisms. We aimed to compare the effect of maintenance dose of ticagrelor versus prasugrel on coronary blood flow velocity (CBFV) during increasing doses of intravenously administered adenosine. Methods and Results—In a prospective, single-center, single-blind, crossover study, 56 patients with non–ST-elevation acute coronary syndrome undergoing percutaneous coronary intervention were randomized to receive either ticagrelor 90 mg BID or prasugrel 10 mg OD with a 15-day treatment period. At the end of each treatment period, CBFV by transthoracic Doppler echocardiography was assessed at baseline and under incremental doses (50 &mgr;g/kg per minute, 80 &mgr;g/kg per minute, 110 &mgr;g/kg per minute, and 140 &mgr;g/kg per minute) of adenosine infusion. Maximal CBFV area under the curve was higher for ticagrelor-treated than for prasugrel-treated patients, with a least squares mean difference of 7.16 (95% confidence interval, 2.61–11.7; P=0.003). Maximal CBFV/baseline CBFV ratio was higher with ticagrelor than prasugrel at 50, 80, and 110 &mgr;g/kg per minute but not at 140 &mgr;g/kg per minute adenosine infusion rate, with mean difference (95% confidence interval) of 0.17 (0.08–0.26; P<0.001), 0.21 (0.02–0.41; P=0.03), 0.24 (0.01–0.47; P=0.04), and 0.14 (−0.12 to 0.4; P=0.3), respectively. Conclusions—In patients with non–ST-elevation acute coronary syndrome undergoing percutaneous coronary intervention, ticagrelor augments CBFV to a greater extent than prasugrel when incremental doses of adenosine are administered. Although exploratory, these results may represent a pleiotropic action of ticagrelor, possibly contributing to its beneficial effects in such patients. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT01642966