Emergency Health Services

STEMI Ambulance Outcome Key Performance Indicators

ST Elevation Myocardial Infarction (STEMI)


STEMI: Evidence of myocardial damage visible on a 12-Lead ECG resulting in ST segment elevation.1.
ICD-10-CA codes: Main Problem =’R9430’ or Main Problem = Acute Myocardial infarction ('I21','I22') AND secondary problem coded as ‘R9430’

NACRS identified
STEMI visits

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All visits reported in NACRS database between April 1, 2013 and March 31, 2016 where one of the diagnoses was STEMI.

Eligible visits

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Adult Ontario patients with a valid health card number

Excludes: (total=466)

  • Patients 18 and under or missing age (n=6)
  • Unknown gender (n=1)
  • Non-Ontario patients (n=447)
  • Patients without a valid health card (n=12 )

Treated in
ED/Cath lab as main problem

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ED visits or cardiac catheterization lab visits for adults with a main problem of STEMI or secondary problem of STEMI with a main problem of Acute Myocardial infarction (AMI).


  • Visits not treated in the ED/Cath lab (n=31)
  • Urgent care center visits (n=186)
  • Main problem is not STEMI or AMI (n=2,381)
  • Palliative care coded on ED visits (n=26)

Initial visit

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ED to ED transfers (n=427) based on the following criteria:

  1. Any ED visit within 6 hours of a previous ED visit;
  2. Any ED visit within 12 hours of a previous ED visit where either the previous ED visit hospital transfer to number matches to second visit hospital number OR the hospital from type or to type is ambulatory care.
  3. Any ED visits within 24 hours where the previous ED visit hospital number matches the hospital from number of the second visit

Final Cohort: Arrival via Ambulance


  • Patients that did not arrive via ambulance (n=7,969)

Mortality Rate

The mortality rate is created by linking the STEMI cohort to Health Analytics Branch’s internal death file. The death file uses several administrative databases (Discharge Abstract Database, National Ambulatory Care Reporting System, Ontario Mental Health Reporting System, Continuing Care Reporting System, OHIP Claims, and Registered Person Database) to determine Ontario resident’s date of death. The STEMI cohort is linked to the death file to determine the 30-day mortality rate post registration date of the ED visit.

Risk Adjustment Factors

When comparing outcomes across regions or over time, it is important to account for differences in patient characteristics. Risk adjustment is a method used to control for patient characteristics that may affect health care outcomes and improves comparability after the pre-existing influence of patient population is removed.  Therefore, risk adjustment allows for fair comparison of performance between the populations such as LHINs.

The selected risk factors were identified based on a literature review, clinical evidence and expert group consultations using the principles of appropriateness, viability (i.e., sufficient number of events) and data availability.  The risk adjustments for the STEMI 30-day mortality rate control for:

  • Fiscal year
  • Fiscal quarter
  • Age
  • Sex
  • Charlson comorbidity index 
  • Previous inpatient admissions
  • Shock
  • Diabetes with complications
  • Congestive heart failure
  • Cancer
  • Cerebrovascular disease
  • Renal failure
  • Arrival by ambulance

Confidence Limit

A confidence interval (CI) reflects the uncertainty surrounding the risk-adjusted mortality ratio. In the analyses presented in this document, the CI indicates that the true value of the risk-adjusted mortality ratio falls between the upper and lower confidence limits 19 times out of 20. The narrower a CI, the more one can be confident in the value of the risk-adjusted mortality ratio.

Reporting Period

The reporting period is based on three years of pooled data from 2013/14 to 2015/16. The data is scheduled to be updated annually where the next period will be based on three years of pooled data from 2014/15 to 2016/17.

For more information, please contact:
Health Analytics Branch

 1Ontario STEMI Bypass Protocol, Cardiac Care Network of Ontario, September, 2015.

For More Information

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