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A key benefit of a prehospital 12‐lead ECG is notification of the receiving facility of an impending STEMI patient’s arrival. Shortening door‐to‐balloon time by 30 minutes reduces in‐hospital mortality from STEMI by about 1% [53]. Implementation of a prehospital 12‐lead ECG program with prehospital notification shortened door‐to‐balloon times by about 60 minutes in San Diego [54]. An evaluation of a large patient registry revealed that prehospital notification and subsequent ED activation of the catheterization team, before patient arrival at the hospital, shortened door‐to‐balloon time by approximately 15 minutes [55].

Occasional false‐positive activation of the PCI team is a necessary by‐product of an aggressive field approach to alerting hospitals about patients with suspected STEMI. One report suggests that up to 15%–20% of team activations may not result in any intervention [56]. The rate of false‐positive activations depends on the pretest probability of finding a STEMI. If EMS clinicians perform 12‐lead ECGs broadly (e.g., everyone over the age of 30 with any of the following characteristics: chest pain, shortness of breath, abdominal pain, diabetes, or cardiac history), the prevalence of actual STEMI is between 0.5% and 5%. The positive predictive value of a “STEMI positive” prehospital 12‐lead ECG may approximate 50% [57]. Such an approach could result in more false positive than true positive activations of the PCI team.

When patients have a reasonable likelihood of STEMI based on their clinical presentations and 12‐lead ECG findings, prehospital cardiac catheterization PCI team activation has consistently been shown to shorten the time to definitive treatment. For example, Nestler et al. showed that prehospital activation of the catheterization laboratory reduced the median door‐to‐balloon times from 59 to 32 minutes [58]. Cone et al. found that field activation of the catheterization laboratory was associated with 37‐ and 35‐minute shorter door‐to‐balloon times than ED activation for walk‐in STEMI patients or STEMI patients arriving by EMS without field activation, respectively [59]. In addition, field activation of the catheterization laboratory was associated with improved performance relative to 90‐minute STEMI treatment benchmarks. Finally, Horvath et al. found similar reductions in the door‐to‐balloon times (44 vs. 57 minutes) in EMS‐transported STEMI patients who had prehospital activation of the cardiac catheterization laboratory compared to those who had the laboratory activated after ED arrival [60].

Field activation of the cardiac catheterization laboratory when a prehospital ECG shows evidence of STEMI is strongly supported by published data. However, in one published study of 27,840 patients with STEMI, where field activation could have occurred, only 41% of the time did field activation happen [61]. EMS systems should work with their PCI‐capable hospitals to establish and promote cardiac catheterization laboratory prehospital STEMI activation protocols and quality improvement monitoring.