No time to waste : Pre-hospital actions and time delays in patients with ST elevation myocardial infarction – temporal trends and prognostic impact on short- and long-term survival

Abstract: Background: In ST-elevation myocardial infarction (STEMI) patients, a rapid diagnosis is imperative to reduce total ischaemic time minimizing risk for heart failure, serious arrhythmias, or death. Prehospital context is complex, and the patient delay constitute major part of the pre-hospital phase. Patient delay has been prone hard to impact but the system delay has had major transformation during the years.  Aim: The overall aim was to explore pre-hospital actions and time delays in STEMI patients, investigating temporal trends and estimate prognostic impact on short- and long-term survival.  Methods: Study I, was a multicentre survey study, exploring decisions, and actions in relation to the choice of first medical contact (FMC). Study II was a sub-study to the multicentre survey, exploring the interaction between tele nurses and callers in authentic calls when the caller with an evolving myocardial infarction (MI) chose to call Swedish health care direct (SHD) as FMC. Study III, was based on the same database as study I, exploring early (< 20 minutes) and late (> 90 minutes) response from symptom onset in STEMI patients. Study IV, was based on SWEDEHEART-registry, investigating temporal trends in pre-specified risk groups for pro-longed pre-hospital delay times (PHDT), estimating cumulative survival in short and long term stratified in six different PHDT groups.  Results: Study I, only half of the patients’ contacted emergency medical services (EMS) as their FMC. Choice of FMC prolonged time to diagnosis in relation of calling EMS. Choosing SHD pro-longed delay to diagnosis with 38 minutes. Study II, four interactions were found between tele-nurses and callers, reasoning, distinct, irrational, and indecisive, and type of interaction could lead or mislead the call moving progressively forward or not. Study III, bystanders calling EMS, men, intensive and alarming symptoms such as dyspnoea and weakness and to interpret symptoms attributed from the heart was associated with a rapid action calling an ambulance within 20 minutes, which was performed by one of five patients. Study IV, trend curves for median PHDT was hump shaped for the 20 years studied. Women, older age, and patients with diabetes had consistent pro-longed PHDT, except for the oldest patients (> 80 years). PHDT was an independent risk for short- and long-term survival. Patients with the shortest PHDT 0-1 hour had the highest mortality up to five days. In five-year follow up this group accompanied with the group within 1-2 hours had highest estimated survival.  Conclusion: Pre-hospital delay is an independent predictor of short- and long-term survival. To interpret symptom correctly and knowledge in how to act, calling an ambulance rapidly, impact time to diagnosis and diminish time delays. Pre-hospital delay merits further attention regarding future interventions.