The stability of myocardial area at risk estimated electrocardiographically in patients with ST elevation myocardial infarction

In patients with ST-elevation myocardial infarction (STEMI) the amount of myocardial area at risk (MaR) indicates the maximal potential loss of myocardium if the coronary artery remains occluded. During the time course of infarct evolution ischemic MaR is replaced by necrosis, which results in a decrease in ST segment elevation and QRS complex distortion. Recently it has been shown that combining the electrocardiographic (ECG) Aldrich ST and Selvester QRS scores result in a more accurate estimate of MaR than using either method alone. Therefore, we hypothesized that the combined Aldrich and Selvester score, indicating MaR, is stable until myocardial reperfusion therapy. In a retrospective analysis of a study population of 114 patients, 33 patients were included. The combined Aldrich and Selvester score was determined in ECGs recorded in the ambulance (ECG1) and in the hospital before reperfusion (ECG2). The combined Aldrich and Selvester score was considered stable if the difference between ECG1 and ECG2 was <4.5-percentage point. Stability of the combined Aldrich and Selvester score was observed in 12/33 patients (36.4%), and in regards to anterior and inferior ST elevation in 4/14 patients (28.6%) and 8/19 patients (42.1%), respectively. The median time between the recording of ECG1 and ECG2 was 75 minutes, however the changes in ECG scores were independent of the time between ECG recordings. Patients not meeting the stability criterion either had a decrease (9 patients) or increase (12 patients) of the combined Aldrich and Selvester score. In conclusion, the ECG estimated MaR was stable between the earliest recording time and initiation of reperfusion treatment only in a subgroup of the patients with STEMI. The findings of this study may suggest heterogeneity in regards to the development of the MaR and could indicate a potential need for differentiation in the acute treatment.