A rapid protocol to identify and exclude acute myocardial infarction: Continuous 12-lead ECG monitoring with 2-hour delta CK-MB

Abstract

A prospective observational study was performed in 706 chest pain patients who underwent our chest pain evaluation protocol which consists of continuous 12-lead ST-segment monitoring with automated serial ECG (SECG) and a 2-hour delta (Δ) CK-MB level determination before ED physician making final disposition decision to determine the incremental value of our 2-hour protocol for identifying myocardial infarction (MI) as compared with the initial ECG in combination with a baseline CK-MB. The initial ECG was obtained on presentation and considered positive if it revealed injury or ischemia. SECGs were obtained at least every 10 minutes and considered positive if it revealed new injury or ischemia. The baseline CK-MB value was considered positive if it was ≥12 ng/mL and index ≥4%. ΔCK-MB was defined as a difference between the 2 hour and baseline CK-MB and was considered positive if the value was ≥+1.5 ng/mL. MI was defined as acute myocardial infarction (AMI) or recent AMI (ie, AMI patients presenting on falling curve of CK-MB). The incremental value of the 2 hour protocol (ie, SECG in conjunction with ΔCK-MB) was more sensitive for identification of MI than the baseline protocol (ie, initial ECG in conjunction with the baseline CK-MB) (94.0% versus 55.4%; P < .0001) and reliably both identified (+LR = 14.6) and excluded MI (−LR = 0.06). SECG monitoring in conjunction with the 2 hour ΔCK-MB allows for early identification and exclusion of MI, and can assist the ED physician in making appropriate treatment and disposition decisions. (Am J Emerg Med 2000;18:698-702.