Early Effects of Ticagrelor Versus Clopidogrel on Peripheral Endothelial Function After Non-ST-Elevation Acute Coronary Syndrome and Assessment of Its Relationship With Coronary Microvascular Function.

Peripheral endothelial dysfunction is an independent predictor of adverse long-term prognosis after acute coronary syndrome. Data are lacking on the effects of oral P2Y12-inhibitors on peripheral endothelial function in non-ST-elevation acute coronary syndrome (NSTEACS). Furthermore, the relation between peripheral endothelial function and invasive indexes of coronary microvascular function in NSTEACS is unclear. Between March 2018 and July 2020, hospitalized patients with NSTEACS were randomized (1:1) to ticagrelor or clopidogrel. Peripheral endothelial function was assessed with brachial artery flow-mediated vasodilation (FMD). Invasive indexes of coronary microvascular function were obtained using an intracoronary pressure-temperature sensor-tipped wire. In 70 patients included, mean age was 58.6 years, 78.6% (n = 55) were male and 20% (n = 14) had diabetes mellitus. Compared with clopidogrel, ticagrelor significantly improved FMD (14.2 ± 5.4% vs 8.9 ± 5.3%, p <0.001) after a median treatment time of 41.2 hours. The FMD was significantly correlated with the index of microcirculatory resistance (IMR) measured in the infarct-related artery (r = -0.38, p = 0.001), with a stronger correlation found in those who did not have percutaneous coronary intervention (r = -0.52, p = 0.03). Using receiver operating characteristic curve analysis, an FMD of 8.2% identified an IMR of >34 as the threshold, with 77.6% sensitivity and 52.4% specificity. In patients who did not have a percutaneous coronary intervention, an FMD of 11.49% identified an IMR of >34 with 84.6% sensitivity and 80% specificity. In conclusion, ticagrelor significantly improved peripheral endothelial function compared with clopidogrel in patients with NSTEACS. There was a significant correlation between brachial artery FMD and IMR of the infarct-related artery.

Use of a high-sensitivity troponin T assay in the assessment and disposition of patients attending a tertiary Australian emergency department: a cross-sectional pilot study.

OBJECTIVE: We examined the disposition and outcomes of patients presenting to the ED with symptoms suggestive of acute coronary syndrome undergoing measurement of troponin T using a highly sensitive assay. METHODS: Troponin T (TnT) was measured in 204 consecutive patients (mean age = 65 [±18] years, 55% men) presenting to the ED with symptoms suggestive of acute coronary syndrome. RESULTS: Ninety-four patients predominantly had chest pain, 34 had dyspnoea and the remainder had various symptoms. Overall, 96 patients had TnT >14 ng/L (upper reference limit), of whom 31 were admitted to the cardiology service (26 had final cardiac diagnosis [five ST-elevation MI, 10 non-ST-elevation MI, one unstable angina and 10 other cardiac]). Among these 96 patients, 41 had chronic kidney disease, 17 had heart failure and seven had sepsis. At 30 days, death rates among patients who had TnT >14 ng/L with non-cardiac diagnoses and in patients who had TnT >14 ng/L with a cardiac diagnosis were 6.6% and 2.9% (P = 0.652); no death and/or MI occurred in patients with normal TnT levels. At late follow up (median 6.8 months) that was obtained in 189 (93% of 204) patients, four had MI and 14 died (three cardiac deaths). CONCLUSIONS: Despite high-sensitivity TnT assay having a high sensitivity and specificity for myocardial necrosis, the majority of unselected consecutive patients attending ED in whom TnT levels were elevated did not have an acute coronary syndrome. Our pilot study suggests that a larger study is needed to provide evidence to modify management algorithms.

Evaluation of a policy of selective drug-eluting stent implantation for patients at high risk of restenosis.

Drug-eluting stent (DES) deployment during percutaneous coronary intervention (PCI) has reduced target-vessel revascularisation rates (TVR). The selective use of DES in patients at highest risk of restenosis may allay concerns about universal compliance of dual antiplatelet therapy for one year, and potentially reduce costs. If this strategy achieved acceptably low TVR rates, such an approach could be attractive. Late clinical outcomes were examined in 2115 consecutive patients (mean age 63±12 years, 75% male, 22% diabetics) who underwent PCI in the first three years from October 2003, after commencing the following selective criteria for DES use: left main stenosis; ostial lesions of major epicardial arteries; proximal LAD lesions; lesions≥20mm in length with vessel diameter≤3.0mm; lesions in vessels≤2.5mm; diabetics with vessel(s)≤3.0mm; and in-stent restenosis. Among patients undergoing PCI, 2075 (98%) patients received stents (29%≥1 DES and 71% bare metal stent [BMS]), and among those who received DES, there was a 92% compliance with these criteria. There were no differences in clinical outcomes between the two stent groups except for definite stent thrombosis, which occurred in 2% after DES, and 0.6% after BMS at one year (p=0.002). With BMS, large coronary arteries (≥3.5mm), intermediate (3-3.49mm) and small arteries (<3mm) in diameter had a TVR rate at one year of 3.6%, 7.2% and 8.2% respectively (p=0.005). It is possible to use selective criteria for DES while maintaining low TVR rates. The TVR rate with BMS was low in those with stent diameters≥3.5mm. The higher DES stent thrombosis rate reflects first generation DES use, though whether routine second generation DES use reduces these rates needs confirmation.

The role of tirofiban in the management of coronary artery disease.

Glycoprotein IIb/IIIa receptor antagonists are potent antiplatelet agents by inhibiting the final common pathway of platelet aggregation. Tirofiban binds specifically to the glycoprotein IIb/IIIa receptor resulting in immediate and extensive inhibition of platelets. Studies have shown that intravenous administration of tirofiban in combination with aspirin and heparin reduces major adverse cardiac events in patients undergoing percutaneous coronary intervention and in those patients with acute coronary syndromes. Large randomised trials using tirofiban demonstrate early clinical and long-term survival benefit in all patient subgroups including high-risk patients undergoing urgent percutaneous coronary intervention, patients undergoing elective intracoronary stent placement and in the medical management of acute coronary syndromes. The use of high-dose bolus tirofiban may provide additional protection in patients at highest risk, whereas the role of tirofiban in the facilitation of primary angioplasty is less well defined. Similar to the other glycoprotein IIb/IIIa receptor antagonists, tirofiban increases the risk of haemorrhagic complications. However, the risk of serious bleeding, including intracranial haemorrhage, remains low and tirofiban does not appear to increase the risk of thrombocytopenia. Overall, the use of tirofiban in coronary artery disease has been shown to be effective, has an acceptable safety profile and is potentially cost-effective.