Robert J. Knotts, MDa, James M. Wilson, MDa, b, Edward Kim, MDa, Henry D. Huang, MDa, Yochai Birnbaum, MDa, b,
AbstractBackground and PurposeWe assess whether the electrocardiographic (ECG) pattern of ST depression in > 7 body surface leads combined with ST elevation in aVR and V1 is predictive of left main coronary artery (LMCA) stenosis or left main equivalent (LMEQ) disease. MethodsWe collected 133 patients showing this particular ECG pattern. Patients with left bundle branch block, ventricular rhythm or ventricular paced rhythm were excluded. ResultsOnly 28% of the patients had non-ST elevation acute coronary syndrome (NSTE-ACS). ECGs were classified as chronic, dynamic or no prior in 28%, 48% and 24%, respectively. A total of 57 patients (44%) underwent coronary angiography (CA). No significant coronary artery disease was found in 26%. LMCA/LMEQ disease was found in only 23% of these patients. The positive predictive value of the ECG pattern was not improved after exclusion of patients with intraventricular conduction abnormalities and left ventricular hypertrophy or in patients with dynamic ECG changes. ConclusionsThis ECG pattern is not always caused by LMCA/LMEQ disease; therefore, the term "suspect circumferential subendocardial ischemia” may be preferred. Other medical conditions may also be associated with a similar ECG pattern. Keyword- Diffuse ST depression;
- Left main stenosis;
- Lead aVR
IntroductionDiffuse 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. Fig. 1. ECG of an 87-year-old man showing sinus rhythm with right bundle branch block and left anterior fascicular block. Patient was known to have severe aortic stenosis. Patient presented with chest pain and was diagnosed as having a non-ST elevation myocardial infarction. There is ST depression with negative T waves in the inferior leads and leads V3–V6 and ST elevation in leads aVR and V1. Subsequent coronary angiography revealed 70% diameter stenosis of his left main coronary artery, 50% stenosis in the distal left anterior descending artery and 50% distal right coronary artery stenosis. Patient underwent aortic valve replacement and coronary artery bypass grafting with left internal mammary artery graft to the left anterior descending artery and a saphenous vein graft to the obtuse marginal branch.
Fig. 2. ECG of a 31-year-old woman with known non-ischemic cardiomyopathy (non-compaction) and recurrent ventricular tachycardia for which a defibrillator was implanted. The ECG shows sinus rhythm with left ventricular hypertrophy. There is ST depression with negative T waves in leads I, II, III, aVF and V4-V6. There is ST elevation in lead aVR, V1 and V2. This pattern was present in several previous ECGs in the preceding 4 months. Coronary angiography did not reveal any significant coronary artery disease. Echocardiogram showed left ventricular ejection fraction of 38% with global hypokinesis.
Fig. 3. ECG of a 67-year-old man with a history of coronary artery disease (two myocardial infarction in the past), severe aortic stenosis, and symptomatic peripheral artery disease who came with progressive symptoms of effort induced angina. ECG shows sinus tachycardia, ST depression in leads I, II, III, aVF, V3–V6 with positive T waves. There is ST elevation in leads aVR and V1. These changes were not present in a previous ECG done several months earlier. Cardiac markers were negative. Coronary angiography revealed significant LMCA and right coronary artery stenosis. The patient underwent CABG and aortic valve replacement.
Fig. 4. ECG of a 55-year-old man with known coronary artery disease and pulmonary hypertension secondary to scleroderma was admitted due to non STE-myocardial infarction. During hospitalization he developed chest pain and ECG shows sinus rhythm with right axis deviation with ST depression and negative T waves in leads I, II, III, aVF, V3–V6. There was also ST elevation in lead aVR. The ST deviation was not present on his admission ECG. Urgent coronary angiography revealed 70% proximal stenosis in his left anterior descending artery. No other lesions were identified. The patient underwent PCI with stenting.
MethodsWe collected 142 electrocardiograms (ECGs) with dates ranging from March 2, 2008 to April, 13 2011 from the ones sent for routine reading at the St. Luke's Episcopal Hospital ECG laboratory and read by one investigator (YB). ECGs showing diffuse ST segment depression in > 7 leads with ST-segment elevation in aVR were collected. Patients with left bundle branch block, QRS duration of > 130 msec, ventricular rhythm or ventricular paced rhythm were excluded. The polarity of the T waves in the leads with maximal ST depression was defined as positive if the terminal part of the T wave was > 0.1 mV above the isoelectric line, or negative. Demographic data, date of ECG, the indication for the ECG, presence of elevated cardiac markers, diagnosis of cardiac conditions (non-ST elevation acute coronary syndrome [NSTE-ACS], non-ischemic dilated cardiomyopathy [NIDCM], ischemic cardiomyopathy, hypertrophic obstructive cardiomyopathy and hypertensive heart disease, and significant valvular disease), performance of coronary angiography (if so, number of diseased vessels [> 70% diameter stenosis] and presence of left main stenosis > 50%), performance of revascularization (percutaneous intervention [PCI] or CABG) following the ECG and the existence of previous ECG (> 24 hours) with the same pattern or without this pattern were obtained from the patients' medical records. Angiographic data were broken up into LMCA, LMEQ disease or three-vessel disease (3VD), two-vessel disease (2VD), one-vessel disease (1VD) or no significant coronary artery narrowing. If the patients were post-CABG and the grafts to the left anterior descending (LAD) and/or obtuse marginals were patent we did not list them as LMCA or LMEQ disease. The ECG patterns were classified as chronic (present for at least 24 hours prior to selected ECG), dynamic (more significant changes or new pattern) or no prior ECG obtained.
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