The stability of the ST segment estimation of myocardial area at risk between the prehospital and hospital electrocardiograms in patients with ST elevation myocardial infarction.

Purpose: Several ST segment deviation scores have been developed to estimate the myocardial area at risk (AAR) during acute myocardial infarction (AMI), which can be used to measure the effectiveness of reperfusion therapy. The purpose of this study was to assess whether one of these ST segment deviation scores (the Aldrich score) is sufficiently stable between the electrocardiogram (ECG) recorded in the ambulance (ECG 1) and the ECG recorded at the time of admission to the hospital (ECG 2) to be used as a baseline estimation of the AAR.

Methods: The Aldrich scores were compared between ECG 1 and ECG 2 in 77 patients who met the criteria for ST elevation myocardial infarction. The ECGs had a time interval of at least 5 minutes and were recorded before reperfusion therapy. Sufficiently stable was defined as 95% of the patients did not show a temporal change of the Aldrich score of more than 4.5%.

Results: The mean time interval between ECG 1 and ECG 2 was 20 ± 9 minutes. Forty-three percent of the total study population showed an "unstable Aldrich score" between ECG 1 and ECG 2. Fifty-seven percent showed a "stable Aldrich score", which means that the 95% standard for sufficiently stable was not fulfilled. By dividing the population based on infarct location, the group with inferior AMI (n = 43) showed more stability (67%) than the group with anterior AMI (n = 34) (44%) (P < .05). However, this remains less than the 95% stability standard.

Conclusion: For both inferior and anterior AMI locations, the Aldrich score was not sufficiently stable to be used as a reliable baseline estimation of the AAR in AMI.