Patients with suspected ACS should have vital signs measured (BP in both arms if dissection is sus- pected)andshouldundergoathoroughcardiovascularexamination. Patients with evidence of LV dysfunction on examination (eg, rales, gallop) or acute mitral regurgitation have a higher likelihood of severe underlying CAD and are at high risk of a poor outcome. In the SHOCK (Should we Emergently Revascularize Occluded Coronaries for Cardiogenic Shock) study, NSTEMI accounted for Other trials have reported lower percentages.92,151 The physical examina- tion may also help identify comorbid conditions (eg, occult GI bleeding) that could impact therapeutic risk and decision making. See Online Data Supplement 2 for additional information on risk stratification. 3.4. Cardiac Biomarkers and the Universal Definition of MI: Recommendations See Table 5 for a summary of recommendations from this sec- tion and Online Data Supplement 3 for additional information on cardiac injury markers and the universal definition of AMI. 3.4.1. Biomarkers: Diagnosis Class I 1. Cardiac-specific troponin (troponin I or T when a contemporary assay is used) levels should be mea- sured at presentation and 3 to 6 hours after symp- tom onset in all patients who present with symptoms consistent with ACS to identify a rising and/or falling (Level of Evidence: A) 2. Additional troponin levels should be obtained beyond 6 hours after symptom onset in patients with normal troponins on serial examination when electrocardio- graphic changes and/or clinical presentation con- fer an intermediate or high index of suspicion for (Level of Evidence: A) 3. If the time of symptom onset is ambiguous, the time of presentation should be considered the time of onset for assessing troponin values.67,68,72 (Level of Evidence: A) Class III: No Benefit 1. With contemporary troponin assays, creatine kinase myocardial isoenzyme (CK-MB) and myoglobin are not useful for diagnosis of ACS.158 164 (Level of Evidence: A) 3.4.2. 