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ST-Segment Elevation in Lead aVR on the Presenting Electrocardiogram

ST-Segment Elevation in Lead aVR on the Presenting Electrocardiogram Much attention has recently been given to the use of ST-segment elevation (STE) in electrocardiographic lead aVR in the setting of acute coronary syndromes as indicative of left main and/or proximal left anterior descending coronary artery disease.1 It must be remembered, however, that STE in lead aVR is not specific for these coronary findings. While Nakamura et al1 discuss a differential diagnosis in their “Comment” section, they fail to mention one of the most common causes of STE in lead aVR, which is left ventricular (LV) hypertrophy. Left ventricular hypertrophy, usually but not always, shifts the QRS axis leftward in the frontal plane, with secondary ST-T abnormalities directed rightward. While the classic “LV strain pattern” is most often noted in limb leads 1 and aVL, because of an ST-segment vector directed between +60° and +240°, there are cases of LV hypertrophy with an ST-segment vector of approximately +270° (as in this case) wherein the ST-segment vector continues to lie on the positive side of the perpendicular to the aVR lead axis and, therefore, generates STE in that lead. The absence of LV hypertrophy by QRS voltage criteria, moreover, does not exclude this diagnosis, since patients with increased LV mass may exhibit repolarization abnormalities alone. With regard to the performance of exercise testing in cases such as this, I would agree with the authors' fourth bullet point in their “Take-Home Points” that use of the Bruce graded exercise testing protocol is relatively contraindicated in a patient such as this. However, I have safely used a combination of Naughton and Bruce exercise testing protocols in ambulatory outpatients presenting with atypical vs perhaps an unstable angina syndrome. Starting at 2.0 mph and 0% grade (2 metabolic equivalents [METs]), there are 3 additional 2-minute stages at 2.0 mph, with progressive increase in grade only, resulting in 1-MET increments. If the patient appears stable at that point, one may switch to Bruce protocol stage 2 at 2.5 mph and 7 METs. Unlike the Modified Bruce protocol, which provides 3 exercise stages prior to Bruce stage 2 and which might be considered in a similar situation, the combination of Naughton and Bruce protocols provides 4 stages of graded exercise prior to Bruce stage 2 with each stage increment, with the transition to the Bruce protocol of no greater than 2 METs. Back to top Article Information Correspondence: Dr Zema, 1131 Stringers Ridge Rd, Unit 14 J, Chattanooga, TN 37405 (mjzema@gmail.com). Financial Disclosure: None reported. References 1. Nakamura K, Berry NC, An PG, Dudzinski DM. Significance of ST-segment elevation in lead aVR. Arch Intern Med. 2012;172(5):389-39122412103PubMedGoogle ScholarCrossref http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archives of Internal Medicine American Medical Association

ST-Segment Elevation in Lead aVR on the Presenting Electrocardiogram

Archives of Internal Medicine , Volume 172 (15) – Aug 13, 2012

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Publisher
American Medical Association
Copyright
Copyright © 2012 American Medical Association. All Rights Reserved.
ISSN
0003-9926
eISSN
1538-3679
DOI
10.1001/archinternmed.2012.2079
Publisher site
See Article on Publisher Site

Abstract

Much attention has recently been given to the use of ST-segment elevation (STE) in electrocardiographic lead aVR in the setting of acute coronary syndromes as indicative of left main and/or proximal left anterior descending coronary artery disease.1 It must be remembered, however, that STE in lead aVR is not specific for these coronary findings. While Nakamura et al1 discuss a differential diagnosis in their “Comment” section, they fail to mention one of the most common causes of STE in lead aVR, which is left ventricular (LV) hypertrophy. Left ventricular hypertrophy, usually but not always, shifts the QRS axis leftward in the frontal plane, with secondary ST-T abnormalities directed rightward. While the classic “LV strain pattern” is most often noted in limb leads 1 and aVL, because of an ST-segment vector directed between +60° and +240°, there are cases of LV hypertrophy with an ST-segment vector of approximately +270° (as in this case) wherein the ST-segment vector continues to lie on the positive side of the perpendicular to the aVR lead axis and, therefore, generates STE in that lead. The absence of LV hypertrophy by QRS voltage criteria, moreover, does not exclude this diagnosis, since patients with increased LV mass may exhibit repolarization abnormalities alone. With regard to the performance of exercise testing in cases such as this, I would agree with the authors' fourth bullet point in their “Take-Home Points” that use of the Bruce graded exercise testing protocol is relatively contraindicated in a patient such as this. However, I have safely used a combination of Naughton and Bruce exercise testing protocols in ambulatory outpatients presenting with atypical vs perhaps an unstable angina syndrome. Starting at 2.0 mph and 0% grade (2 metabolic equivalents [METs]), there are 3 additional 2-minute stages at 2.0 mph, with progressive increase in grade only, resulting in 1-MET increments. If the patient appears stable at that point, one may switch to Bruce protocol stage 2 at 2.5 mph and 7 METs. Unlike the Modified Bruce protocol, which provides 3 exercise stages prior to Bruce stage 2 and which might be considered in a similar situation, the combination of Naughton and Bruce protocols provides 4 stages of graded exercise prior to Bruce stage 2 with each stage increment, with the transition to the Bruce protocol of no greater than 2 METs. Back to top Article Information Correspondence: Dr Zema, 1131 Stringers Ridge Rd, Unit 14 J, Chattanooga, TN 37405 (mjzema@gmail.com). Financial Disclosure: None reported. References 1. Nakamura K, Berry NC, An PG, Dudzinski DM. Significance of ST-segment elevation in lead aVR. Arch Intern Med. 2012;172(5):389-39122412103PubMedGoogle ScholarCrossref

Journal

Archives of Internal MedicineAmerican Medical Association

Published: Aug 13, 2012

Keywords: electrocardiogram,st segment elevation

References