Background: Acute myocardial infarction is one of the most common presentations of coronary artery disease (CAD). Although coronary angiography remains the gold standard for identification of the infarctrelated artery (IRA), conventional 12-lead electrocardiography (ECG) is an essential tool for diagnosis, risk stratification and prognosis. If specific ECG patterns can be recognized, it will be possible to determine the IRA and size of the ventricular area that is jeopardized. The existing ECG algorithms have good sensitivity for the right coronary artery (RCA) and good specificity for the left circumflex artery (LCx) as predictors of IRA in patients with acute inferior-wall myocardial infarction (IWMI), while the specificity for the RCA and sensitivity for the LCx are modest.
OBJECTIVE: To evaluate deviations in lead aVR to predict IRA in patients with IWMI, and to validate several commonly used 12-lead ECG characteristics.
Methods: A total of 585 consecutive patients with a first occurrence of acute IWMI were analyzed for the association between ECG and IRA diagnosed using coronary angiography. Subsequently, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of depression in lead aVR, along with various commonly used ECG criteria for predicting the IRA, were estimated using coronary angiographic findings as the gold standard.
Results : The RCA and the LCx were found to be the IRA in 415 (71%) and 170 (29%) patients, respectively. It was observed that the absence of ST depression in lead aVR, ST depression in lead I ≥0.5 mm, ST depression in lead aVL >1 mm and ST elevation in lead III > ST elevation in lead II had excellent sensitivity and specificity in predicting the RCA as the culprit vessel. Similarly, ST depression in lead aVR ≥0.5 mm, the ratio of ST depression in lead V3 to ST elevation in lead III >1.2 had excellent sensitivity and specificity in predicting the LCx as the culprit vessel.
Conclusion: These findings reveal that evaluation of ST deviations in lead aVR offers good sensitivity and specificity for LCx and RCA occlusions. The authors believe that using multiple ECG criteria may provide earlier and better identification of the IRA.
