Clinical Characteristics and Risk factors of Acute Myocardial Infarction in the Elderly after Hip Fracture: A Retrospective Study

Abstract Background: The purpose of this retrospective study is to investigate the characteristics and determine the risk factors of Acute Myocardial Infarction (AMI) after hip fracture in the Elderly. Methods: We collected clinical data of older patients who suffered hip fracture from January 2019 to December 2020. The data collected include demographic and clinical characteristics, underlying diseases and laboratory results. In AMI patients, we further collected typeof myocardial infarctions, clinical symptoms, electrocardiogram (ECG), Killip class and diagnosis method. We identified independent risk factors for AMI after hip fracture using Least absolute shrinkage and selection operator (LASSO) regression and multivariate logistic regression analyses. Results: There are 40 (4.2%) cases developed AMI in all 958 old hip fracture patients. There were 685 (71.5%) female patients and 273(28.5%) male patients. Among 40 AMI patients, 38(95.0%) had Type 2 myocardial infarction (T2MI) and2 (5.0%) had Type 1 myocardial infarction (T1MI). The majority of these ECG were ST segment depression (57.5%). 16(40.0%) AMI patients initially present with chest tightness and 14(35.0%) patients presented asymptomatic. The Killip class of the AMI was mostly Killip I(60.0%). AMI patients were significantly older(age≥80，p=0.030) and had more comorbidities(p=0.001). Most of AMI patients were complicated with hypertension(60.0%), coronary heart disease(CHD) (45.0%), diabetes(42.5%) and more prone to have anemia(71.5%), hypoproteinemia( 52.5%), electrolyte disorders (45.0%), heart failure(42.5%) deep vein thrombosis (32.5%), pneumonia (32.5%). The C-reactive protein (CRP) on admission was higher(p=0.000) and albumin (Alb) (p=0.000) was lower in the AMI group. Higher age (OR 2.187, 95%CI 1.028-4.654), combined with diabetes (OR 5.701, 95%CI 2.411-13.479), hemoglobin (Hb)≤100 g/L(OR 3.969, 95%CI 1.467-10.737), CRP≥40mg/L (OR 7.013, 95%CI 2.865-17.170), and ALb≤35 g/L (OR 2.139, 95%CI 1.030-4.441) were independent risk factors for AMI after hip fracture. Conclusion: Elderly patients who have diabetes are prone to AMI after hip fracture. Higher CRP, lower Hb and Alb at admission also increase the risk of AMI. After traumatic stress, they are more likely to have a variety of complications. It is necessary to strengthen the management of AMI patients to reduce the occurrence of AMI and other complications.