Distinguishing the right coronary artery from the left circumflex coronary artery as the infarct-related artery in patients undergoing primary percutaneous coronary intervention for acute inferior myocardial infarction.

Aims: Aim of this study was to investigate the diagnostic accuracy of the conventional electrocardiogram (ECG) algorithm [ST-segment elevation (STE) in lead III exceeding that in lead II combined with ST-segment depression in lead I or aVL] for identification of the infarct-related artery (IRA) in a large cohort of patients undergoing primary percutaneous coronary intervention (PCI) for inferior wall STE myocardial infarction (STEMI).

Methods And Results: We included 1131 patients with inferior STEMI, who underwent primary PCI between 2000 and 2007 and of whom a pre-procedural 12-lead ECG was available, recorded immediately prior to PCI. The IRA was determined during emergency angiography. Coronary angiography confirmed the right coronary artery (RCA) as the IRA in 895 patients (79%) with inferior wall STEMI. Application of the ECG algorithm resulted in 624 true positive cases of acute RCA obstruction (sensitivity: 70%, 95% CI: 67 -73%) and 170 cases with true negative result (specificity: 72%, 95% CI: 66-77%). Sensitivity of >90% was established in patients with cumulative ST-segment deviation above median (>18.5 mm).

Conclusion: The conventional ECG algorithm showed a low sensitivity for the non-invasive diagnosis of RCA occlusion in an all-comer, inferior STEMI cohort undergoing primary PCI. Sensitivity was only sufficient in patients with extensive ST-segment deviation.