Diversity of Electrocardiographic Patterns in Left Main Culprit Acute ST-Elevation Myocardial Infarction.

Background: The clinical implications of diverse electrocardiographic (ECG) findings in acute ST-elevation myocardial infarction (STEMI) patients with left main (LM) culprit are not well understood.

Methods: Using the multicenter Midwest STEMI consortium database of 12,403 patients, we identified 68 (0.5%) with unprotected LM culprits. The activating ECGs (aECG) were classified into three patterns: a) Non-ST-elevation (NSTE); b) ST-elevation (STE); or c) Atypical.

Results: The median age was 68 (IQ percentile: 58-83) years, 67% were male. LM occlusion (TIMI flow: 0-1) was observed in 20 (29%) and sub-occlusive LM (TIMI flow: 2-3) in 48 (71%) patients. Worse in-hospital adverse outcomes (cardiac arrest: 50% vs. 18%, p=0.016; shock: 75% vs. 36%, p=0.007; and death, 75% vs. 44%, p=0.03) occurred among patients with an occlusive versus sub-occlusive LM culprit, respectively. Both a NSTE-type (n=14; 20.5%) and STE-type (n=14; 20.5%) aECG pattern were observed in the minority of patients limiting the diagnostic utility for identifying the presence of LM culprit acute myocardial infarction (aggregate sensitivity: 41%; specificity:71%). A STE-type aECG was more frequently associated with LM occlusion (n=10/14; 71%) compared with either a NSTE- or Atypical-type ECG pattern (10/54; 19%; p=0.001; aggregate sensitivity: 50%, specificity: 92%) and higher adverse in-hospital cardiac events.

Conclusion: Previously reported archetypal ECG patterns associated with LM culprit MI were observed in a minority of patients, limiting thier diagnostic utility. A STE-type pattern more accurately detected the presence of occlusive LM coronary flow and was associated with worse in-hospital outcomes.