Primary percutaneous coronary intervention for patients presenting with ST-elevation myocardial infarction: process improvements in rural prehospital care delivered by emergency medical services.

BACKGROUND: Safe and effective patient care for ST-elevation myocardial infarction (STEMI) relies on prompt emergency medical service (EMS) and established care coordination with receiving hospitals to conduct primary percutaneous coronary intervention (PCI). Likewise, a new emphasis has been placed on first medical contact-to-balloon (E2B) times as opposed to door-to-balloon times, identifying prehospital care as an important contributing factor for high-quality STEMI care. Therefore, we evaluated EMS processes of care before and after a period of continuous quality improvement to improve E2B times in our rural tertiary care medical center.

METHODS: A retrospective, consecutive cohort study was conducted on 177 patients who received primary PCI at Dartmouth-Hitchcock Medical Center, a rural hospital, from January 1, 2006 to October 31, 2009. This cohort was stratified from January 1, 2008 to May 1, 2008 (n = 88) and May 1, 2008 to October 31, 2009 (n = 89), to acknowledge periods of no improvement (pre) and continuous quality improvement (post) in STEMI care. Primary outcome measures included frequency of non-PCI-capable hospital bypass, E2B, and frequency of prehospital electrocardiogram (ECG) and cardiac catheterization laboratory (CCL) activation. Descriptive statistics and log-rank tests were used to determine whether measures differed significantly by time period. A time-to-event analysis was conducted using a Cox proportional hazards model to assess the impact of outcomes measures on E2B pre/post-May 1, 2008.

RESULTS: Patients who presented before May 1, 2008 had longer E2B times compared with patients in the post-May 1, 2008 cohort (145.1 minutes vs 115.2 minutes, t test P = .01). A log-rank test confirmed this (pre: 130 minutes vs post: 106 minutes, χ(2) = 5.3, log-rank P = .02). Similarly, patients who presented before May 1, 2008 had lower percentages of prehospital ECGs (49% vs 80%, P = .001) and CCL activations (4% vs 32%, P < .001). When prehospital ECGs (140 minutes vs 106 minutes, χ(2) = 5.9, log-rank P = .01) or CCL activations (125 minutes vs 98 minutes, χ(2) = 4.2, log-rank P = .04) were conducted, E2B times were significantly reduced. Patients who received both prehospital ECGs and prehospital CCL activations had significantly reduced E2B times compared with those who did not (125 minutes vs 91 minutes, χ(2) = 4.8, P = .02).

CONCLUSIONS: The time saving benefits of prehospital ECGs may not be fully realized unless prehospital CCL activations also occur. EMS providers achieved further reductions in median E2B of approximately 24 minutes when prehospital ECGs were combined with prehospital CCL activation. Every effort should be made by PCI-capable medical centers to assess prehospital STEMI care and to integrate EMS providers into regional STEMI care quality improvement initiatives and education.