Introduction: Acute myocardial infarction (AMI) is one of the most common causes of death, especially in those who develop cardiogenic shock (CS). The ECG is a main tool in making a diagnosis of the localization of myocardial infarction (MI) and the possible location of the culprit lesion. ST-segment elevation (STE) in lead aVR is of great importance because it is a sign of either left main coronary artery (LM) occlusion or of proximal left anterior descending artery (LAD) or left circumflex artery (ACx) occlusion. STE in aVR > V1 STE suggests of the LM occlusion. The opposite ratio suggests of proximal LAD occlusion. Other ECG features of LM obstruction include diffuse ST-segment depression in precordial and inferior leads. Such patient demands an urgent myocardial reperfusion either via percutaneous coronary intervention (PCI) or, extremely rare, a coronary artery bypass grafting (CABG). CABG accounts < 5% of primary interventions after AMI (1-3).

Case report: 70-years-old female patient was initially admitted to Clinic for Surgery, where femoropopliteal bypass was done, due to right superficial femoral artery occlusion. Postoperatively the patient developed stenocardia and was transferred to Coronary Care Unit. The ECG showed STE in aVR > STE in V1 and ST depression in other leads. Laboratory tests showed high troponin levels. Echocardiography showed hypokinesis of anteroseptolateral left ventricular wall with mild reduction in LV systolic function (EF 45%). Meanwhile, the patient developed CS, with high lactate levels. After patient stabilization by inotropes, an urgent coronarography was performed. It showed subocclusion of LM, as well as subocclusion of ostial LAD and left circumflex artery (ACx) which is additionally significantly stenosed in proximal segment, and proximal significant stenosis of right coronary artery (RCA). The patient was immediately transferred to cardiac surgery where triple CABG was created, LIMA with LAD and obtuse marginal branch (OM1) and RCA with vein saphena magna. Postoperatively, the patient was hemodynamically stable with normal LVEF.

Conclusion: Previous studies showed that STE in aVR
> STE in V1 suggest LMCA occlusion which we did not find in our patient. New recommendations for universal definition of myocardial infarction suggest that STE in aVR >1 mm is equivalent to myocardial infarction with STE.