Cardiac Markers

Course overview

The electrocardiogram plays a significant role in the identification of acute MI in symptomatic patients. However, it is not foolproof. ECG changes only occur in about 50% of acute MI patients. There are small MIs, reinfarctions, extensions of MIs, non Q-wave MIs and MIs that do not even have ST segment elevation (NSTEMI). Also, ECG criteria in patients with previous left bundle branch block (LBBB) are more difficult to interpret. What happens to the other 50%? Are their heart attacks destined to remain undiagnosed? Do we have to wait for the ECG changes to manifest? (If they even do!) Thankfully, the ECG is not the only tool in the cardiac diagnostic tool bag. Chemical markers are more reliable over the long term and some can assist in determining severity of the MI which the ECG cannot do well.