A novel prehospital electrocardiogram score predicts myocardial salvage in patients with ST-segment elevation myocardial infarction evaluated by cardiac magnetic resonance.

OBJECTIVES

We hypothesized that prehopsital ECG scores can identify ST-segment elevation myocardial infarction (STEMI) patients in whom time delay is particularly important for myocardial salvage.

METHODS

We evaluated the Anderson-Wilkins (AW) score (which designates the acuteness of ischemia) and grade 3 ischemia (GI3) (which identifies severe ischemia) in the prehospital ECG and compared them to the myocardial salvage index (MSI) assessed by cardiac magnetic resonance.

RESULTS

In 150 patients, system delay (alarm to balloon inflation) (β = -0.304, p < 0.001) and AW score (β = 0.364, p < 0.001) correlated with MSI. AW scores ≥3 (p < 0.001) and GI3 (p = 0.002) predicted the MSI. We formed 4 subgroups combining AW scores (<3 or ≥3) and grades of ischemia (<GI3 or =GI3), yielding a prehospital salvage score of 1-4, which predicted the MSI (p < 0.001), left ventricular ejection fraction at 3 months (p = 0.017), infarct size (p < 0.001), and troponin T (p < 0.001). MSI was only dependent on system delay in patients with acute ischemia (AW score = 3) with (β = -0.687, p = 0.005) or without (β = -0.454, p < 0.001) severe ischemia (GI3).

CONCLUSION

In patients with STEMI, the novel prehospital salvage score identifies subgroups in which myocardial salvage is particularly time dependent.