Author: Dr. Hans Murcia
Early repolarization, also known as J-point elevation, may present with ST segment elevations similar to STEMI on ECG. Given the risks and expense of activating the Cath lab for every patient with ST elevation, it is important to recognize true STEMI from early repolarization.
How can we use the ECG computerized interpretation to help us differentiate acute STEMI from early repolarization.
Take a group of patients with known STEMI in which the ECGs only had subtle changes indicative of STEMI, derive a criteria sensitive to the detection of STEMI and then test it with a group of ECGs with known early repolarization. The purpose was to design an algorithm using the criteria above to improve the computerized ECG interpretation to interpret STEMI and early repolarization more accurately.
There are three criteria that when multiplied by constants and applied in an inequality provides a way to significantly improve the computerized interpretation of ECG regarding STEMI vs early repolarization
There is a large number of conditions that present with ST segment elevations on ECG that do not represent myocardial infarction. Conditions such as pulmonary embolism, hyperkalemia, acute pericarditis and early repolarization tend to present with ST segment changes that would not necessitate thrombolytics or PCI. Left ventricular hypertrophy and early repolarization are some of the most common conditions for which patients are unnecessarily taken to the cath lab. The criteria presented in this paper, provides an algorithm that takes into account three subtle variables that can be calculated to improve the computerized interpretation differentiation between STEMI and early repolarization. The criteria that indicate STEMI were large R-wave amplitude, significant ST elevation in lead V3, and prolonged QTc.
Limitations of the study include the impracticality to implement these new criteria in our daily practice. It is worth noting that this set of criteria is specific and sensitive in detecting STEMI from early repolarization, but the magnitude of the measurements is not something that the provider cannot easily calculate at bedside. These calculations can only be performed by the ECG machine. Thus, this criteria is only beneficial if it can be integrated into the existing algorithm of the ECG machine; otherwise, it is purely academic.
There are multiple conditions (cardiac and pulmonary) that present with ST segment elevations that are not STEMI, and thus do not require thrombolytics or PCI. Early repolarization is one of those conditions and there are criteria that when integrated in the ECG machine, it can help to differentiate the two.
Smith SW. Electrocardiographic differentiation of early repolarization from subtle anterior ST-segment elevation myocardial infarction. Cardiology/original research. Annals of Emergency Medicine. Vol 60, No I: July 2012