The early diagnosis of acute myocardial infarction. Comparison of a simple algorithm with a computer program for electrocardiogram interpretation.

The sensitivity and specificity of electrocardiographic (ECG) interpretation by a simple algorithm was compared with a computer read ECG machine. Clinical data and ECG findings on 264 consecutive patients admitted to a coronary care unit with suspected acute myocardial infarction were prospectively entered into an algorithm with 13 end-points. These end-points were compared with the interpretations of a computer read ECG machine (Marquette MAC PC). 86 patients (32.5%) had confirmed acute infarction. 85% of those with infarction had some form of ST elevation on their initial ECG. Patients with ST elevation presented earlier (4.9 +/- 4.9 versus 8.0 +/- 9.7 hours after symptom onset, p < 0.001), and were older (66.5 +/- 11.0 versus 62.0 +/- 12.5 years, p < 0.01) than those without infarction. According to the algorithm 94.2% of patients with infarction had some form of ECG abnormality, compared with 55.6% of those without infarction (p < 0.001). The area under the receiver operating characteristic (ROC) curve of the algorithm was 92.3% of the area of the graph. This was more (p < 0.01) than the area under the ROC curve of the interpretations of the computer read ECG machine (83.9%). Marked ST elevation with reciprocal changes was the most specific indicators of infarction (Likelihood ratio 51.7). The algorithm, therefore, was comparatively sensitive and specific in the early diagnosis of acute infarction.