Serial Creatine Kinase‐MB Results Are a Sensitive Indicator of Acute Myocardial Infarction in Chest Pain Patients with Nondiagnostic Electrocardiograms: The Second Emergency Medicine Cardiac Research Group Study

Abstract

Objective: To determine the test performance characteristics of serial creatine kinase-MB (CK-MB) mass measurements for acute myocardial infarction (MI) in patients presenting to the ED with chest pain and nondiagnostic ECGs. Methods: A prospective, observational test performance study was conducted. Hemodynamically stable patients aged 2 2 5 years with chest discomfort, but without ECGs diagnostic for MI, were enrolled at 7 university teaching hospitals. Presenting ECGs showing >1 -mV ST-segment elevation in 2 2 electrically contiguous leads were considered diagnostic for MI; patients with diagnostic ECGs on presentation were excluded. Real-time, serial CK-MB mass levels were obtained using a rapid serum immunochernical assay at the time of ED presentation (0-hour) and 3 hours later (3-hour). The following testing schemes were evaluated for their sensitivity and specificity for detection of MI during patient evaluation in the ED: 1) an elevated ( 2 8 ng/mL) presenting CK-MB level; 2) an elevated presenting and/or 3-hour CK-MB level; 3) a significant increase (i.e., 2 3 ng/mL) within the range of normal limits for CK-MB concentrations during the 3-hour period (A CK-MB); andor 4) development of ST-segment elevation during the 3 hours (second ECG). Results: Of the 1,042 patients enrolled, 777 (74.6%) were hospitalized, including all 67 MI patients (8.6% of admissions). As a function of duration of time in the ED, the test performance characteristics of serial CKMBs for MI ( Conclusion: Serial CK-MB monoclonal antibody mass measurements in the E D can identify MI patients with initially nondiagnostic ECGs. CK-MB sensitivity significantly increases over 3 hours of observation of stable chest discomfort patients in the ED; it also increases as a function of the total interval from onset until enzyme measurement.

2011 ACCF/AHA Focused Update Incorporated Into the ACC/AHA 2007 Guidelines for the Management of Patients With Unstable Angina/Non–ST-Elevation Myocardial Infarction

“…212,214,249 -251 One study of 1,042 patients found the addition of a 3-h delta CK-MB to result in a sensitivity of 93% and a specificity of 94% for MI. 248 In another study of 2,074 consecutive ED chest pain patients, a 2-h delta CK-MB in conjunction with a 2-h delta troponin I measurement had a sensitivity for acute MI of 93% and specificity of 94% in patients whose initial ECG was nondiagnostic for injury. When combined with physician judgment and selective nuclear stress testing, the sensitivity for MI was 100% with specificity of 82%, and the sensitivity for 30-d ACS was 99.1% with specificity of 87%.…”

“…A newer method to both identify and exclude MI within 6 h of symptoms is to rely on changes in serum marker levels (delta values) over an abbreviated time interval (e.g., 2 h) as opposed to the traditional approach of performing serial measurements over 6 to 8 h. 212,214,[247][248][249][250] Because assays are becoming more sensitive and precise, this method permits the identification of increasing values while they are still in the normal or indeterminate range of the assay. By relying on delta values for the identification or exclusion of MI, higherrisk patients with positive delta values can be selected earlier for more aggressive anti-ischemic therapy (e.g., GP IIb/IIIa inhibitors), and lower-risk patients with negative delta values can be considered for early stress testing.…”

2012 ACCF/AHA Focused Update Incorporated Into the ACCF/AHA 2007 Guidelines for the Management of Patients With Unstable Angina/Non–ST-Elevation Myocardial Infarction

“…218,220,[255][256][257] One study of 1042 patients found the addition of a 3-h delta CK-MB to result in a sensitivity of 93% and a specificity of 94% for MI. 254 In another study of 2074 consecutive ED chest pain patients, a 2-h delta CK-MB in conjunction with a 2-h delta troponin I measurement had a sensitivity for acute MI of 93% and specificity of 94% in patients whose initial ECG was nondiagnostic for injury. When combined with physician judgment and selective nuclear stress testing, the sensitivity for MI was 100% with specificity of 82%, and the sensitivity for 30-d ACS was 99.1% with specificity of 87%.…”

“…251 In the TACTICS TIMI-28 study, subgroups of patients with no ECG changes, a low TIMI score, and no cTn elevation showed no benefit from the invasive strategy, whereas those with positive cTn, independent of the presence of elevated CK-MB levels, showed markedly reduced odds of adverse clinical events of 0. 13 A newer method to both identify and exclude MI within 6 h of symptoms is to rely on changes in serum marker levels (delta values) over an abbreviated time interval (eg, 2 h) as opposed to the traditional approach of performing serial measurements over 6 to 8 h. 218,220,[253][254][255][256] Because assays are becoming more sensitive and precise, this method permits the identification of increasing values while they are still in the normal or indeterminate range of the assay. By relying on delta values for the identification or exclusion of MI, higher-risk patients with positive delta values can be selected earlier for more aggressive anti-ischemic therapy (eg, GP IIb/IIIa inhibitors), and lower-risk patients with negative delta values can be considered for early stress testing.…”

Can Electrocardiographic Criteria Predict Adverse Cardiac Events and Positive Cardiac Markers?

“…Creatine kinase-MB (CK-MB) levels help guide disposition decisions and offer prognostic value. 7,8 The cardiac troponins have proven even more valuable in assessing risk and guiding initial treatment. [9][10][11][12][13][14] Hence, ECG findings predictive of positive cardiac markers might be helpful as well.…”