Keyword

• Diffuse ST depression; 
• Left main stenosis; 
• Lead aVR

Introduction

Diffuse ST segment depression in the inferior and anterolateral leads that is associated with ST segment elevation in leads aVR and V₁ (Fig. 1, Fig. 2, Fig. 3 and Fig. 4) is thought to represent circumferential subendocardial ischemia, suggesting an injury vector directed toward the ventricular chamber. When accompanied by angina at rest, this ECG is believed to have a 75% predictive accuracy of left main coronary artery (LMCA) occlusion or three-vessel coronary artery disease.¹ The current recommendation by the American Heart Association/American College of Cardiology Foundation/Heart Rhythm Society (AHA/ACCF/HRS) for "resting ECGs that reveal ST-segment depression greater than 0.1 mV in 8 or more body surface leads coupled with ST-segment elevation in aVR and/or V₁ but are otherwise unremarkable,” is that the automated interpretation should suggest "ischemia due to multivessel or LMCA obstruction”.¹ In this document, presence of typical symptoms is not mentioned and the guidelines are read as a "stand alone” recommendation for ECG interpretation either at bed side or off line. Moreover, there is no specification as to what is an ECG that is "otherwise unremarkable”. For example, does the presence of Q waves or QRS axis deviation considered "remarkable”? Furthermore, it is unclear whether in patients with diffuse ST depression with ST elevation in aVR as a chronic stable pattern, the same association with LMCA exist. These recommendations were endorsed by the recently published 2012 European Society of Cardiology Guidelines for the management of ST elevation acute myocardial infarction.² Dual antiplatelet therapy is recommended by the guidelines for all patients presenting with acute coronary syndromes (ACS), regardless of whether they are to receive percutaneous coronary intervention (PCI) or medical treatment alone.³ Oral P2Y₁₂receptor inhibitors, such as clopidogrel, prasugrel and ticagrelor, improve clinical outcomes in patients with ACS, but are associated with an increased risk of operative bleeding when administered within five days of coronary artery bypass graft (CABG) surgery. Since most of the patients with LMCA disease or left main equivalent (LMEQ, proximal narrowing in both the left anterior descending and left circumflex arteries) will likely need CABG surgery, some authors have recommended withholding P2Y₁₂ receptor inhibitors in patients presenting with such ECG pattern until the treatment plan has been established.⁴ Thus, early identification of patients with ACS due to LMCA or LMEQ disease is of extreme importance. However, in our experience, the same ECG pattern of diffuse ST segment depression with ST elevation in lead aVR may be seen in patients with cardiomyopathies as well as left ventricular hypertrophy with repolarization changes and in numerous other medical conditions that may or may not be associated with circumferential subendocardial ischemia. Diffuse ST depression with ST elevation in aVR is not even the most common ECG pattern seen in patients presenting with LMCA obstruction.^{5, 6 and 7} This study assesses the diagnostic accuracy of the criteria defined by the 2009 AHA/ACCF/HRS recommendations as written.¹ The main objectives of this study were to assess 1) the prevalence of acute ischemia caused by LMCA or LMEQ disease among patients having the ECG pattern of diffuse ST depression along with ST elevation in lead aVR; 2) what other medical conditions are associated with such an ECG pattern; and 3) whether ECG confounders, such as left ventricular hypertrophy (LVH) or various forms of intraventricular conduction delay affect the accuracy of predicting LMCA/LMEQ by this particular ECG pattern. In the present study, we used a common situation in which the cardiologist is analyzing ECGs from various areas of a tertiary hospital (in patients, intensive care units, as well as outpatient clinics) without complete access to patients' clinical data.