Dynamic changes in electrocardiographic findings between initial and follow-up electrocardiograms (ECGs) have rarely been studied for disease severity and differential diagnosis in non-ST elevation acute coronary syndrome. We aimed to determine whether the changes in staple variables on ECG can assist in distinguishing between neuropsychiatric or gastrointestinal disorders (mild non-ischemic disorders), heart failure, and NSTE-ACS (non-ST elevation acute coronary syndrome).

This retrospective study enrolled 1279 patients who presented with ischemic symptoms; were diagnosed with NSTE-ACS, acute heart failure, and mild disorders; and underwent echocardiography and coronary angiography. After performing propensity matching of the ECG follow-up interval, 184 patients with symptom onset within 48 h were included and analyzed.

As a discriminator for NSTE-ACS, the maximum change in the T/QRS ratio in two contiguous leads was superior to the maximum change in ST segment depression, T wave inversion, and ST/T ratio. ECGs of patients with NSTE-ACS and heart failure showed a tendency to increase and decrease the T/QRS ratio change, respectively. Compared with regional wall motion abnormality, the change in troponin I/h and the maximum change in ST segment depression and T-wave inversion, the most deviated T/QRS ratio change from 1 (>1.5 or < 0.5) in two contiguous leads was the most significant discriminator for disease severity and differential diagnosis (standardized β = 0.545, p < 0.001).

The maximum changes in the T/QRS ratio in two contiguous leads can assist in distinguishing disease severity and acute mimicking disease such as acute heart failure in patients with suspected ACS.