4. Secondary effectiveness outcomes Using the same modelling approach as previously described (i.e., b. primary effectiveness outcome), multivariable logistic regression will be performed to identify baseline characteristics that are independently associated with false-positive cardiac catheterization laboratory activation among patients who are candidate for primary PCI. A first-order interaction term involving prehospital cardiac catheterization laboratory activation will be tested for statistical significance. If appropriate, analysis will be stratified according to prehospital versus hospital cardiac catheterization laboratory activation. Then medical outcomes will be compared between false positive and true positive cardiac catheterization laboratory activation after adjusting for quintile of propensity score.