Mode of hospital presentation in patients with non–ST-elevation myocardial infarction: Implications for strategic management

Tymchak, Wayne; Armstrong, Paul W.; Westerhout, Cynthia M.; Sookram, Sunil; Brass, Neil; Fu, Yuling; Welsh, Robert C.

doi:10.1016/j.ahj.2011.06.011

« Previous Next »American Heart Journal
Volume 162, Issue 3 , Pages 436-443, September 2011

Mode of hospital presentation in patients with non–ST-elevation myocardial infarction: Implications for strategic management

Wayne Tymchak, MD, FACC
- Division of Cardiology, Department of Medicine, University of Alberta, Alberta, Canada
- Mazankowski Alberta Heart Institute, 8440 112 St. NW, Edmonton, Alberta, Canada
- Royal Alexandra Hospital, Edmonton, Alberta, Canada
Paul W. Armstrong, MD, FACC
- Division of Cardiology, Department of Medicine, University of Alberta, Alberta, Canada
- Mazankowski Alberta Heart Institute, 8440 112 St. NW, Edmonton, Alberta, Canada
- Royal Alexandra Hospital, Edmonton, Alberta, Canada
Cynthia M. Westerhout, PhD
- Division of Cardiology, Department of Medicine, University of Alberta, Alberta, Canada
- Royal Alexandra Hospital, Edmonton, Alberta, Canada
Sunil Sookram, MD
- Division of Cardiology, Department of Medicine, University of Alberta, Alberta, Canada
- Royal Alexandra Hospital, Edmonton, Alberta, Canada
Neil Brass, MD
- Division of Cardiology, Department of Medicine, University of Alberta, Alberta, Canada
- Royal Alexandra Hospital, Edmonton, Alberta, Canada
Yuling Fu, MD
- Division of Cardiology, Department of Medicine, University of Alberta, Alberta, Canada
- Royal Alexandra Hospital, Edmonton, Alberta, Canada
Robert C. Welsh, MD, FACC
- Division of Cardiology, Department of Medicine, University of Alberta, Alberta, Canada
- Mazankowski Alberta Heart Institute, 8440 112 St. NW, Edmonton, Alberta, Canada
- Royal Alexandra Hospital, Edmonton, Alberta, Canada
- Reprint requests: Robert C. Welsh, MD, FRCPC, FACC, 2C2 Cardiology, WMC – Mazankowski Alberta Heart Institute, 8440 112 St. NW, Edmonton, Alberta,Canada T6G 2B7.

Received 23 February 2011; accepted 20 June 2011. published online 10 August 2011.

Introduction

Contemporary non–ST-elevation myocardial infarction–acute coronary syndrome guidelines emphasize early-risk stratification and optimizing therapy including an invasive strategy in high-risk patients. To assess the feasibility of initiating this strategy in the prehospital environment, we examined how such patients are transported to hospital, their risk profile, and the proportion potentially eligible for such a strategy.

Methods

Consecutive patients with ST-segment elevation myocardial infarction admitted in Edmonton were studied between September and November 2008 and divided according to their mode of transport to hospital: emergency medical services (EMS) versus self-presenting. Baseline characteristics, GRACE Risk Score, blinded core laboratory electrocardiogram analysis, cardiac biomarkers, in-hospital procedures, and outcomes were analyzed.

Results

Thirty-five percent (93/263) of patients presented via EMS and often to percutaneous coronary intervention hospitals, that is, 64.5% versus 44.1% (P = .0016). They were older (75 vs 62 years, P < .001), more often female (43% vs 28.1%, P < .001), diabetic (34.4% vs 22.9%, P = .045), and hypertensive (72.0% vs 57.1%, P = .017) and had higher GRACE Risk Scores (median 166 vs 130, P < .001). Electrocardiogram analysis revealed more baseline Q waves (38.8% vs 25.5%, P = .031) and ST depression ≥2 mm (P = .027) in EMS-transported patients. Fewer EMS patients underwent cardiac catheterization (60.2% vs 88.2%, P < .001), and a paradoxical relationship existed between catheterization rates and GRACE Risk Score in the total cohort (low-risk: 93.4% vs high-risk: 59.3%, P < .001). The composite of death/re–myocardial infarction/congestive heart failure/shock was greater in EMS patients (unadjusted odds ratio 3.96, 95% CI 1.80-8.69, P = .001); these differences were attenuated after GRACE Risk Score adjustment.

Conclusion

Regional strategies using risk-based triage, early medical therapy, and timely triage to percutaneous coronary intervention centers represents an unrealized opportunity to enhance ST-segment elevation myocardial infarction care.