BACKGROUND: ST-elevation myocardial infarction (STEMI) is a type of myocardial infarction caused by a buildup of plaque or clot in the coronary arteries. There are approximately 750,000 STEMI cases each year in the United States. The American Heart Association's Mission Lifeline initiative aimed to optimize prehospital emergency medical services (EMS) and enhance STEMI triage rates through improved standardized protocol. This study evaluates the implementation of Mission Lifeline techniques by Polk County Fire Rescue (PCFR) on improved EMS-to-balloon (E2B) times and triage rates. METHODS: Data from PCFR, Florida's 4th largest EMS system, were analyzed quarterly from 2015 to 2023. The study included patients with chest pain that were >
35 years of age. RESULTS: Among 2,585 patients, the percentage meeting the 90-min EMS-to-Balloon time increased from 74% in 2015 to 84% by the year 2019. The average annual under-triage rate for STEMI decreased from ranging from 2% in 2015 to 4% in 2017 to below 1% after the year 2020, reaching as low as 0% in 2021 and 2023. Over-triage rates initially fluctuated, increasing to a height of 12% by 2017, but decreased to <
3% by 2022 and further dropped to 0.6% of cases were over-triage by 2024. CONCLUSION: Implementation of Mission Lifeline procedures, including obtaining pre-hospital 12-lead ECG and hospital pre-activation, significantly enhanced STEMI care. These interventions led to improved E2B times and more accurate prehospital STEMI identification, underscoring the importance of coordinated, protocol-driven prehospital STEMI care in improving patient outcomes.