Prehospital times in primary percutaneous coronary intervention: The new frontier for improvement

Background: Primary percutaneous coronary intervention (PPCI) remains the treatment of choice for patients presenting with ST-elevation myocardial infarction (STEMI). With STEMI, total ischemic time is an important predictor of myocardial injury and other short and long-term adverse events including mortality. Several studies have examined ‘Door to Balloon’ times, but few studies have examined pre-hospital and in hospital component times as individual pieces that make up total ischemic time. Methods: Total ischemic and component times for patients who received PPCI from 2012- 2015 in the Queen Elizabeth-II Halifax Infirmary were described. Median total ischemic times and component times were calculated and compared. Regression modeling was performed to identify which component times and component variables explained the most variation in total ischemic times. Results: 551 patients who had successful PPCI and complete component times were identified. Most were male (76%) with a median age of 59.2 years (IQR: 52.7-68.0 years). The longest component time was ‘Symptom Onset to First Medical Contact’ (Median: 61 min, IQR: 32-138 min). ‘Symptom Onset to First Medical Contact’ was found to account for most of the variation seen in total ischemic time (R2= 61%). Conclusions: We determined that most time in the component of receiving PPCI lies in the pre-hospital setting and that component variables including EHS use and pre-activation of the cardiac catheter lab reduce total ischemic time. More research needs to be devoted to reducing patient delay, as there appears to be little room for improvement in hospital component times.