Characteristics of ST Elevation Myocardial Infarction Patients Who Do Not Undergo Percutaneous Coronary Intervention After Prehospital Cardiac Catheterization Laboratory Activation.

OBJECTIVES: To assess the clinical and electrocardiographic characteristics of patients diagnosed with ST elevation myocardial infarction (STEMI) that are associated with an increased likelihood of not undergoing percutaneous coronary intervention (PCI) after prehospital Cardiac Catheterization Laboratory activation in a regional STEMI system.

METHODS: We performed a retrospective analysis of prehospital Cardiac Catheterization Laboratory activations in Mecklenburg County, North Carolina, between May 2008 and March 2011. Data were extracted from the prehospital patient record, the prehospital electrocardiogram, and the regional STEMI database. The independent variables of interest included objective patient characteristics as well as documented cardiac history and risk factors. Analysis was performed using descriptive statistics and logistic regression.

RESULTS: Two hundred thirty-one prehospital activations were included in the analysis. Five independent variables were found to be associated with an increased likelihood of not undergoing PCI: increasing age, bundle branch block, elevated heart rate, left ventricular hypertrophy, and non-white race. The variables with the most significance were any type of bundle branch block [adjusted odds ratios (AOR), 5.66; 95% confidence interval (CI), 1.91-16.76], left ventricular hypertrophy (AOR, 4.63; 95% CI, 2.03-10.53), and non-white race (AOR, 3.53; 95% CI, 1.76-7.08). Conversely, the only variable associated with a higher likelihood of undergoing PCI was the presence of arm pain (AOR, 2.94; 95% CI, 1.36-6.25).

CONCLUSIONS: Several of the above variables are expected electrocardiogram mimics; however, the decreased rate of PCI in non-white patients highlights an area for investigation and process improvement. This may guide the development of prehospital STEMI protocols, although avoiding false positive and inappropriate activations.