Angiotensin (Ang Ⅱ),a main effector peptide of the renin-angiotensin system (RAS),mediates a hormonal action in the maintenance of blood pressure and electrolyte levels,and thus fluid homeostasis.Recent studies have implicated that it correlates with tumor growth,angiogenesis,metastasis and it has drawn more and more attention.Many studies show that Ang Ⅱ-AT1R/AT2R play crucial roles in tumor growth,metastasis,invasion and tumor angiogenesis,which are formed new targets for treating malignant tumors.

Objective:To assess the age-related differences in the management strategies and outcomes of patients with acute coronary syndrome (ACS) under the chest pain center model.Methods:Clinical data of 2 833 patients with ACS were enrolled in the retrospective observational registry between January 2017 and June 2019 at 11 hospitals with chest pain centers in Chengdu. The patients were divided into four groups according to their ages: < 55 years old group ( n = 569), 55-64 years old group ( n = 556), 65-74 years old group ( n = 804), ≥ 75 years old group ( n = 904). The collected data included the patients' demographic characteristics, cardiovascular risk factors, medical history, symptoms and signs of onset, experimental examination, types of ACS and the time from the symptom to the hospital (S-to-D), etc., and the clinical characteristics, management strategies, all-cause mortality in the hospital, and the incidence of major adverse cardiovascular and cerebrovascular events (MACCE) within 1 year after discharge were compared. The primary end point was the clinical outcome of ACS patients in different age groups, including all-cause deaths in the hospital and the incidence of MACCE within 1 year after discharge. The secondary end point was the proportion of ACS patients underwent percutaneous coronary intervention (PCI) in different age groups. Multivariate Logistic regression was used to analyze the risk factors of all-cause deaths in ACS patients. Kaplan-Meier curve was used to express the incidence of MACCE within 1 year after discharge in different age groups. Multivariate Cox regression was used to analyze the factors affecting the incidence of MACCE within 1 year after discharge of ACS patients. Results:As age increased, the proportion of male patients gradually decreased, and the percentages of male patients aged < 55 years old, 55-64 years old, 65-74 years old, and ≥ 75 years old were 87.2% (496/569), 77.0% (428/556), 66.4% (534/804), and 60.1% (543/904), respectively; and ACS patients combined with hypertension, diabetes, coronary heart disease, and stroke history were more common [the percentages of patients with hypertension aged < 55 years old, 55-64 years old, 65-74 years old, ≥ 75 years old were 41.3% (235/569), 52.2% (290/556), 59.7% (480/804), and 66.9% (605/904); the percentages of diabetes were 18.6% (106/569), 25.5% (142/556), 27.0% (217/804), and 28.2% (255/904); the percentages of coronary heart disease were 10.1% (57/564), 13.9% (77/555), 17.6% (141/803), and 23.7% (213/899); the percentages of stroke were 0.7% (4/564), 4.0% (22/552), 4.5% (36/801), and 8.6% (77/894)]. But the percentages of patients with a history of active smoking, typical chest pain/chest tightness and dyslipidemia were significantly reduced [the percentages of smoking history were 60.2% (340/565), 48.0% (266/554), 33.7% (270/801), and 21.7% (195/899), typical chest pain/chest tightness were 96.9% (536/553), 96.4% (516/535), 91.8% (716/780), 90.2% (776/860); the percentages of dyslipidemia were 11.2% (63/565), 9.2% (51/553), 5.7% (46/802), and 4.9% (44/896)], the time of S-to-D was significantly prolonged [minutes: 176.0 (73.5, 557.0), 194.5 (89.3, 682.3), 221.0 (98.8, 940.5), and 270.0 (115.0, 867.0)], hemoglobin (Hb) level was significantly reduced(g/L: 145.44±17.43, 135.95±19.25, 129.75±19.03, 122.19±20.55), and the incidence of non-ST-segment elevation myocardial infarction (NSTEMI) increased significantly [18.6% (106/569), 20.5% (114/556), 26.6% (214/804), 26.5% (240/904)], and the differences were statistically significant (all P < 0.05). The proportion of Killip grade Ⅲ -Ⅳ were the highest in patients aged ≥ 75 years old, 9.0% and 12.6%, respectively. Compared with the groups aged < 55 years old, 55-64 years old, and 65-74 years old, the proportion of patients aged ≥ 75 years old who underwent PCI was the lowest, and the all-cause mortality in the hospital and the incidence of 1-year MACCE of patients underwent PCI were significantly lower than those of patients underwent conservative treatment [6.0% (28/463) vs. 10.4% (45/434), 14.6% (43/294) vs. 24.3 % (55/226), both P < 0.05]. As age increased, the hospital all-cause mortality and the 1-year MACCE incidence increased (all-cause mortality rates in < 55 years old, 55-64 years old, 65-74 years old, ≥ 75 years old groups were 0.9%, 2.2%, 5.5%, 8.3%, and the 1-year MACCE incidences were 5.0%, 6.7%, 13.9%, 18.7%, both P < 0.01). The multivariate Logistic regression analysis showed that age, cardiogenic shock, ST-segment elevation myocardial infarction (STEMI), the number of vascular disease and underwent PCI were the independent risk factors of all-cause mortality [the odds ratio ( OR) and 95% confidence interval (95% CI) were 1.644 (1.356-1.993), 11.794 (7.469-18.621), 2.449 (1.419-4.227), 1.334 (1.096-1.624), 0.391 (0.247-0.619), all P < 0.001]. Cox regression analysis showed that age, STEMI, the number of vascular disease and underwent PCI were independent risk factors of the occurrence of MACCE within 1 year after discharge [hazard ratio ( HR) and 95% CI were 1.354 (1.205-1.521), 1.387 (1.003-1.916), 1.314 (1.155-1.495), 0.547 (0.402-0.745), all P < 0.05]. Conclusions:In the chest pain center model, compared with other age of ACS patients, the proportion of NSTEMI in elderly patients group aged ≥ 75 years old was higher, the proportion of PCI was lower, and the clinical outcome was worse. However, the prognosis of elderly patients receiving PCI treatment was better than the patients receiving conservative treatment.