A new electrocardiographic pattern indicating inferior myocardial infarction

Background: We identified a specific pattern that does not display contiguous ST-segment elevation (STE), indicating acute inferior myocardial infarction (MI) with concomitant critical stenoses on the other coronary arteries. We sought to define the frequency, underlying anatomic substrate, diagnostic power and prognostic implications of this pattern.

Methods: One thousand patients with a diagnosis of non-STEMI were enrolled as the study group. Within the same date range, all patients with inferior STEMI and 1000 patients, who had been excluded for MI (no-MI), were also enrolled. The coronary angiograms were reviewed by two interventional cardiologists, who were blinded to the ECGs. Echocardiographic wall motion bullseye displays and coronary angiography maps were constructed for each group. The dead or alive status was checked from the electronic national database.

Results: The final study population consisted 2362 patients. The prespecified ECG pattern was observed in 6.3% (61/966) of the non-STEMI cohort and 0.5% (5/1000) of no-MI patients. These patients had a larger infarct size as evidenced by 24-hour troponin levels, higher frequency of angiographic culprit lesion, and higher frequency of composite acute coronary occlusion endpoint compared to their non-STEMI counterparts. On the other hand, they had a similar in-hospital (5% vs. 4%, respectively; P = 0.675) and one-year mortality compared to the patients with inferior STEMI (11% vs. 8%, respectively; P = 0.311).

Conclusion: We here define a new ECG pattern indicating inferior MI in patients with concomitant critical lesion(s) in coronary arteries other than the infarct-related artery. Patients with this pattern have multivessel disease and higher mortality.