Acute coronary syndrome with a totally occluded culprit artery: relation of the ST injury vector with ST-elevation and non-ST elevation ECGs.

Background: In acute coronary syndrome (ACS), ST-segment elevation (STE), often associated with a completely occluded culprit artery, is an important ECG criterion for primary percutaneous coronary intervention (PCI). However, several studies showed that in ACS a completely occluded culprit artery can also occur with a non-ST-elevation (NSTE) ECG. In order to elucidate reasons for this discrepancy we examined ST injury vector orientation and magnitude in ACS patients with and without STE, all admitted for primary PCI and having a completely occluded culprit artery.

Methods: We studied the ECGs of 300 ACS patients (214/86 STE/NSTE; 228/72 single/multivessel disease) who had a completely occluded culprit artery during angiography prior to primary PCI. The J+60 injury vector orientation and magnitude were computed from Frank XYZ leads derived from the 10-s standard 12-lead ECG.

Results: Demographic and anthropomorphic characteristics of the STE and NSTE patients did not differ. STE patients had a higher rate of right coronary artery occlusions, and a lower rate of left circumflex occlusions than NSTE patients (43 vs. 31%, and 13 vs. 22%, respectively; P<0.05). Injury vector elevation and magnitude were larger in STE than in NSTE patients (32° ± 37° vs. 6° ± 39°, and 304 ± 145 μV vs. 134 ± 72 μV, respectively; P<0.0001).

Conclusion: STE criteria favor certain injury vector directions and larger injury vector magnitudes. Obviously, several ACS patients with complete culprit artery occlusions requiring primary PCI do not fulfill these criteria. Our study suggests that STE-NSTE-based ACS stratification needs further enhancement.