Introduction: Patients with ST-elevation myocardial infarction are at risk of developing cardiac arrest. A validated tool for predicting cardiac arrest would help physicians recognize these high-risk patients earlier. This study assessed the usefulness of various score systems in predicting cardiac arrest in patients hospitalized for ST-elevation myocardial infarction. Methods: Patients’ data were retrieved from the hospital’s ST-elevation myocardial infarction registry records. Patients aged 18 years or older seen at the emergency department with a diagnosis of ST-elevation myocardial infarction between 1 July 2013 and 30 June 2014 were enrolled. The Thrombolysis in Myocardial Infarction score, the 6-month Global Registry of Acute Coronary Event risk score, CHADS2 score, and HEART score were calculated and compared. Results: A total of 249 patients were recruited. The Thrombolysis in Myocardial Infarction score, 6-month Global Registry of Acute Coronary Event risk score, CHADS2 score, and HEART scores were calculated. In total, 41 (16.5%) patients had cardiac arrest at emergency department or during hospitalization and 12 (29.3%) of them survived. The 6-month Global Registry of Acute Coronary Event risk score had the biggest area under the receiver-operating characteristic curve (0.72). Conclusion: The 6-month Global Registry of Acute Coronary Event risk score is more useful in predicting cardiac arrest in patients hospitalized for ST-elevation myocardial infarction than the other three scores. It is recommended that the 6-month Global Registry of Acute Coronary Event risk score be calculated for identifying emergency department patients hospitalized for ST-elevation myocardial infarction who are at risk of cardiac arrest during their hospital stay.