Objective: To investigate the influence of obstructive sleep apnea syndrome (OSAS) on myocardial work and prognosis in patients with acute myocardial infarction (AMI). Methods: Patients with complete follow-up data diagnosed with AMI who were admitted to the Second Affiliated Hospital of Suzhou University due to chest pain within 24 hours attacks from February 2020 to January 2022 were retrospective enrolled in the study and were split into two groups based on sleep apnea hypoventilation index (AHI): OSAS group (AHI≥5/h) and non-OSAS group (AHI<5/h). Follow up for (12.4±0.1) months. There were finally 210 AMI patients including 130 males and 80 females with (69.6±9.4) years, ranging from 36 to 83 years. The general characteristics, haematological index, echocardiographic parameters, myocardial work (MW) and the occurrence of major adverse cardiac events (MACE) in 1 year between the two groups were quantified. Logistic regression analysis and receiver operating characteristic (ROC) curve were used to assess the risk of MACE in patients with AMI. Results: There were 50 cases in the OSAS group and 160 cases in the non-OSAS group. Compared with the non-OSAS group, OSAS group demonstrated higher BMI,neck circumference, Killip grade,GRACE score,ESS score,SYNTAX score, the number of diseased vessels and higher prevalence of hypertension, hyperlipidemia and smoking history. The differences were statistically significant (P<0.05). There were also statistically significant differences in sleep study result and hematological indexesof of cTnT, NT-ProBNP, and creatinine between the two groups (P<0.05). The general work index (GWI) of the OSAS group was lower than that of the non-OSAS group [(870.1±435.6) vs (1 005.0±313.6) mmHg% (1 mmHg=0.133 kPa), P=0.017]; The general myocardial active work (GCW) of the OSAS group was lower than that of the non-OSAS group [(1 046.7±472.2) vs (1 262.7±274.9) mmHg%, P=0.003]; The general work efficiency (GWE) of the OSAS group was lower than that of the non-OSAS group [(79.8±14.2)% vs (84.5±5.8)%, P=0.001]; The general reactive power (GWW) of the OSAS group was higher than that of the non-OSAS group [(312.2±163.2) vs (264.0±85.1) mmHg%, P=0.007]. There were 10 cases (20.0%) of MACE in the OSAS group and 13 cases (8.1%) in the non OSAS group, with a statistically significant difference (P=0.001).The combination of decreased OSAS (OR=4.039, 95%CI: 1.159-6.918), decreased myocardial work, including GCW [OR=0.850 (95%CI: 0.742-0.958)], GWE [OR=0.871 (95%CI: 0.818-0.924)], GWI (OR=0.862, 95%CI: 0.732-0.991), increased GWW (OR=2.425, 95%CI: 1.482-3.368), and increased GRACE score (OR=3.775, 95%CI: 2.314-5.236) increased the risk of MACE in AMI patients (all P<0.05). The area under the ROC curve (AUC) for predicting MACE in AMI using OSAS+myocardial work+GRACE score was 0.779 (95%CI: 0.717-0.834), with a sensitivity of 65.2% and a specificity of 84.5%. After the combination of the three, there were statistically significant differences compared to the AUC of combined OSAS, GRACE score, and myocardial work (all P<0.05). Conclusions: The MW of AMI patients with OSAS decreased compared to those without OSAS. The combination of OSAS and MW can improve the predictive value of MACE in patients with AMI.