Prediction of Post-Discharge Bleeding in Elderly Patients with Acute Coronary Syndromes: Insights from the BleeMACS Registry.

BACKGROUND: A poor ability of recommended risk scores for predicting in-hospital bleeding has been reported in elderly patients with acute coronary syndromes (ACS). No study assessed the prediction of post-discharge bleeding in the elderly. The new BleeMACS score (Bleeding complications in a Multicenter registry of patients discharged with diagnosis of Acute Coronary Syndrome), was designed to predict post-discharge bleeding in ACS patients. We aimed to assess the predictive ability of the BleeMACS score in elderly patients. METHODS: We assessed the incidence and characteristics of severe bleeding after discharge in ACS patients aged ≥ 75 years. Bleeding was defined as any intracranial bleeding or bleeding leading to hospitalization and/or red blood transfusion, occurring within the first year after discharge. We assessed the predictive ability of the BleeMACS score according to age by Fine-Gray proportional hazards regression analysis, calculating receiver-operating characteristic (ROC) curves and the area under the ROC curves (AUC). RESULTS: The BleeMACS registry included 15,401 patients of whom 3,376/15,401 (21.9%) were aged ≥ 75 years. Elderly patients were more commonly treated with clopidogrel and less often treated with ticagrelor or prasugrel. Of 3,376 elderly patients, 190 (5.6%) experienced post-discharge bleeding. The incidence of bleeding was moderately higher in elderly patients (hazard ratio [HR], 2.31, 95% confidence interval [CI], 1.92-2.77). The predictive ability of the BleeMACS score was moderately lower in elderly patients (AUC, 0.652 vs. 0.691, p = 0.001). CONCLUSION: Elderly patients with ACS had a significantly higher incidence of post-discharge bleeding. Despite a lower predictive ability in older patients, the BleeMACS score exhibited an acceptable performance in these patients.

Prevalence and outcome of patients with cancer and acute coronary syndrome undergoing percutaneous coronary intervention: a BleeMACS substudy.

BACKGROUND: The prevalence and outcome of patients with cancer that experience acute coronary syndrome (ACS) have to be determined. METHODS AND RESULTS: The BleeMACS project is a multicentre observational registry enrolling patients with acute coronary syndrome undergoing percutaneous coronary intervention worldwide in 15 hospitals. The primary endpoint was a composite event of death and re-infarction after one year of follow-up. Bleedings were the secondary endpoint. 15,401 patients were enrolled, 926 (6.4%) in the cancer group and 14,475 (93.6%) in the group of patients without cancer. Patients with cancer were older (70.8±10.3 vs. 62.8±12.1 years, P<0.001) with more severe comorbidities and presented more frequently with non-ST-segment elevation myocardial infarction compared with patients without cancer. After one year, patients with cancer more often experienced the composite endpoint (15.2% vs. 5.3%, P<0.001) and bleedings (6.5% vs. 3%, P<0.001). At multiple regression analysis the presence of cancer was the strongest independent predictor for the primary endpoint (hazard ratio (HR) 2.1, 1.8-2.5, P<0.001) and bleedings (HR 1.5, 1.1-2.1, P=0.015). Despite patients with cancer generally being undertreated, beta-blockers (relative risk (RR) 0.6, 0.4-0.9, P=0.05), angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (RR 0.5, 0.3-0.8, P=0.02), statins (RR 0.3, 0.2-0.5, P<0.001) and dual antiplatelet therapy (RR 0.5, 0.3-0.9, P=0.05) were shown to be protective factors, while proton pump inhibitors (RR 1, 0.6-1.5, P=0.9) were neutral. CONCLUSION: Cancer has a non-negligible prevalence in patients with acute coronary syndrome undergoing percutaneous coronary intervention, with a major risk of cardiovascular events and bleedings. Moreover, these patients are often undertreated from clinical despite medical therapy seems to be protective. Registration:The BleeMACS project (NCT02466854).

Catalytic mechanism of hydroxynitrile lyase from Hevea brasiliensis: a theoretical investigation.

Density functional theory (DFT) calculations using the hybrid functional B3LYP have been performed to investigate the catalytic mechanism of hydroxynitrile lyase from Hevea brasiliensis (Hb-HNL). This enzyme catalyzes the cleavage of acetone cyanohydrin to hydrocyanic acid plus acetone. Two models (A and B) of the active site consisting of 105 and 155 atoms, respectively, were constructed on the basis of the crystal structure. Good consistency between the two models provides a verification of the proposed mechanism. Our calculations show that the catalytic reaction proceeds via three elementary steps: (1) deprotonation of the OH-Ser80 by His235 and concomitant abstraction of a proton from the substrate hydroxyl by Ser80; (2) the C-C bond cleavage of the acetone cyanohydrin; and (3) protonation of the cleaved cyanide by His235. The cleavage of the C-C bond is the rate-limiting step with the overall free energy barrier of 13.5 kcal/mol for relatively smaller model A (14.9 kcal/mol for a larger model B) in the protein environment, which is in good agreement with experimental rate. The present results give support to the previously proposed general acid/base catalytic mechanism, in which the catalytic triad acts as a general acid/base. Moreover, the calculated results for model C, with the positive charge of Lys236 removed from model A, show that Lys236 with the positive charge plays a vital role in lowering the reaction barrier of the rate-determining and helps in stabilizing the negatively charged CN(-) by forming a hydrogen bond with the substrate, consistent with the experimental analysis.