ACLS review: Acute Coronary Syndromes Part 3

Cardiac Enzymes

·         Cardiac troponin is the preferred biomarker and is more sensitive

·         Cardiac troponins are useful in diagnosis, risk stratification, and determination of prognosis

·         An elevated level of troponin correlates with an increased risk of death, and greater elevations predict greater risk of adverse outcome.

Note:  In the patients with STEMI reperfusion therapy should not be delayed pending results of biomarkers. Important limitations to these tests exist because they are insensitive during the first 4 to 6 hours of presentation unless continuous persistent pain has been present for 6 to 8 hours.

If biomarkers are initially negative within 6 hours of symptom onset, it is recommended that biomarkers should be remeasured between 6 to 12 hours after symptom onset (Class I, LOE A).

Assess initial 12 lead ECG

·         The 12 lead ECG stands at the center of the decision making for the care of the patient with acute coronary syndrome

·         The 12 lead ECG should be obtained with 10 minutes of arriving in the ED.

Note:  Prehospital 12-lead ECGs speed the diagnosis, shorten the time to reperfusion (fibrinolytics45–52 or primary percutaneous coronary intervention [PPCI]53–60). EMS personnel should routinely acquire a 12-lead electrocardiogram (ECG) as soon as possible for all patients exhibiting signs and symptoms of ACS

ECG classifications

·         ST-segment elevation

·         ST depression or T-wave inversion

·         Nondiagnostic or normal ECG

ECG classification: ST Elevation

·         Must search for ST elevation > 1mm in 2 or more contiguous leads

·         Must search for new or presumably new LBBB

Note:  Men 40 years or older:  J-point elevation (2 mm) in leads V2 and V3 and (1 mm)

Men <40 years old:  J-point elevation (2.5 mm) in leads V2 and V3 and (1 mm) in all other leads.
Women:  J-point elevation (1.5 mm) in leads V2 and V3 and (1 mm) in all other leads.
Circulation. 2010; 122: S787-S817 doi: 10.1161/CIRCULATIONAHA.110.971028

Measuring ST-elevation

·         The J point is the point where the QRS complex meets the ST segment

·         Measure ST elevation 0.04sec (1mm) to the right of the J point

·         The baseline for this measurement is the P wave to the end of the T wave