Abstract: OBJECTIVE To explore the influencing factors for lower respiratory tract infection in elderly patients with acute myocardial infarction after percutaneous coronary intervention（PCI）.METHODS A retrospective analysis of 200 elderly patients with acute myocardial infarction who underwent emergency PCI at the First Affiliated Hospital of Nanchang University from May 2016 to Jan. 2020 was Established.Based on the occurrence of lower respiratory tract infection after 3 months, we divided the patients into two groups, 130 cases in the presence of postoperative lower respiratory tract infection group（study group） and 70 cases in the absence of postoperative lower respiratory tract infection group（control group）. the general data in both group, such as gender, age, body mass, serum levels of high mobility group box 1（HMGB1）, Interleukin-6（IL-6）, tumor necrosis factor-α（TNF-α）, and high sensitivity C-reactive protein（hs-CRP）,Analyzed was to summarize the factors influencing lower respiratory tract infections in elderly patients with acute myocardial infarction after PCI and determine the value of the above serum indicators using subject operating characteristic（ROC） curves.RESULTS The differences in the history of hypertension, operation time and length of hospitalization between the two groups were significant（P＜0.05）; HMGB1, IL-6, TNF-α, and hs-CRP in the study group were significantly higher than those in the control group after PCI（P＜0.05）; Operation time was the influencing factors of lower respiratory tract infection in elderly patients with acute myocardial infarction after PCI（P＜0.05）; ROC analysis showed that the area under the curve of the combined index is 0.871（0.795-0.946）, which were higher than any single index.CONCLUSION Serum HMGB1, IL-6, HS-CRP and TNF-α are risk factors for lower respiratory tract infection in elderly patients with acute myocardial infarction after PCI, the combined detection of these indicators has a high diagnostic value for the occurrence of lower respiratory tract infections in elderly patients with acute myocardial infarction after PCI.