Objective: The American Heart Association (AHA) recommends a benchmark door-to-electrocardiogram (ECG) time of 10 minutes for acute myocardial infarction patients, but this is based on expert opinion (level of evidence C). We sought to establish an evidence-based benchmark door-to-ECG time.
Methods: This retrospective cohort study used a population-based sample of patients who suffered an ST elevation myocardial infarction (STEMI) in Ontario between 1999 and 2001. Using cubic smoothing splines, we described (1) the relationship between door-to-ECG time and ECG-to-needle time and (2) the proportion of STEMI patients who met the benchmark door-to-needle time of 30 minutes based on their door-to-ECG time. We hypothesized nonlinear relationships and sought to identify an inflection point in the latter curve that would define the most efficient (benefit the greatest number of patients) door-to-ECG time.
Results: In 2,961 STEMI patients, the median door-to-ECG and ECG-to-needle times were 8.0 and 27.0 minutes, respectively. There was a linear increase in ECG-to-needle time as the door-to-ECG time increased, up to approximately 30 minutes, after which the ECG-to-needle time remained constant at 53 minutes. The inflection point in the probability of achieving the benchmark door-to-needle time occurred at 4 minutes, after which it decreased linearly, with every minute of door-to-ECG time decreasing the average probability of achievement by 2.2%.
Conclusions: Hospitals that are not meeting benchmark reperfusion times may improve performance by decreasing door-to-ECG times, even if they are meeting the current AHA benchmark door-to-ECG time. The highest probability of meeting the reperfusion target time for fibrinolytic administration is associated with a door-to-ECG time of 4 minutes or less.