Lead aVL on electrocardiogram: emerging as important lead in early diagnosis of myocardial infarction?

Serial Electrocardiograms-An Unsung Hero

This case report describes a patient in their 60s with diabetes and hypertension who presented to the emergency department with retrosternal chest pain.

T-wave inversions in inferior ST-elevation myocardial infarction - A case of "inferior Wellens sign"

BACKGROUND

Although T-wave inversions are nonspecific, in the appropriate clinical setting, the pattern of negative biphasic T-waves or T-wave inversion in V2-V3 can indicate critical stenosis of the left anterior descending coronary artery (i.e. "anterior Wellens sign"). Recently tall T-waves in V2-V3 have been reported in association with posterior reperfusion (i.e."posterior Wellens sign"). Less commonly, negative biphasic T-waves or T-wave inversions in the inferior leads have been reported in association with critical stenosis of the right coronary artery (RCA) or left circumflex artery (LCx). We present a case where T wave inversions (i.e. "inferior Wellens sign") and a tall T-wave in V2-V3 (i.e. "posterior Wellens sign") preceded the development of an inferior-posterior ST-elevation myocardial infarction (STEMI).

CASE REPORT

A 37-year-old man presented to the Emergency Department for one day of chest pain. On arrival, his pain had resolved, and his 1st ECG showed inverted/biphasic T-waves in lead III and aVF and a tall T wave in V2-V3. Three- and one-half hours after arrival, his chest pain returned and his ECG showed an inferior-posterior STEMI. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: New, focal T-wave inversions in an anatomic distribution may be an early warning sign of impending myocardial infarction. Careful attention to the T-waves during asymptomatic periods may assist in identifying patients that may have critical stenosis of an underlying coronary artery. In this case, T-wave inversions in the inferior leads, along with a tall T-wave in V2-V3, were seen prior to the development of an inferior-posterior STEMI.

Why complicate an important task? An orderly display of the limb leads in the 12-lead electrocardiogram and its implications for recognition of acute coronary syndrome

Background

In the standard ECG display, limb leads are presented in a non-anatomical sequence: I, II, III, aVR, aVL, aVF. The Cabrera system is a display format which instead presents the limb leads in a cranial/left-to-caudal/right sequence, i.e. in an anatomically sequential order. Lead aVR is replaced in the Cabrera display by its inverted version, −aVR, which is presented in its logical place between lead I and lead II.

Main text

In this debate article possible implications of using the Cabrera display, instead of the standard, non-contiguous lead display, are presented, focusing on its use in patients with possible acute coronary syndrome. The importance of appreciating reciprocal limb-lead ECG changes and the diagnostic and prognostic value of including aVR or lead −aVR in ECG interpretation in acute coronary syndrome is covered. Illustrative cases and ECGs are presented with both the standard and contiguous limb lead display for each ECG.

A contiguous lead display is useful when diagnosing acute coronary syndrome in at least 3 ways: 1) when contiguous leads are present adjacent to each other, identification of ST elevation in two contiguous leads is simple; 2) a contiguous lead display facilitates understanding of lead relationships as well as reciprocal changes; 3) it makes the common neglect of lead aVR unlikely.

Conlusions

It is logical to display the limb leads in their sequential anatomical order and it may have advantages both in diagnostics and ECG learning.

Pitfalls in Electrocardiographic Diagnosis of Acute Coronary Syndrome in Low-Risk Chest Pain

Less than half of patients with a chest pain history indicative of acute coronary syndrome have a diagnostic electrocardiogram (ECG) on initial presentation to the emergency department. The physician must dissect the ECG for elusive, but perilous, characteristics that are often missed by machine analysis. ST depression is interpreted and often suggestive of ischemia; however, when exclusive to leads V1–V3 with concomitant tall R waves and upright T waves, a posterior infarction should first and foremost be suspected. Likewise, diffuse ST depression with elevation in aVR should raise concern for left main- or triple-vessel disease and, as with the aforementioned, these ECG findings are grounds for acute reperfusion therapy. Even in isolation, certain electrocardiographic findings can suggest danger. Such is true of the lone T-wave inversion in aVL, known to precede an inferior myocardial infarction. Similarly, something as ordinary as an upright and tall T wave or a biphasic T wave can be the only marker of ischemia. ECG abnormalities, however subtle, should give pause and merit careful inspection since misinterpretation occurs in 20–40% of misdiagnosed myocardial infarctions.

Does T wave inversion in lead aVL predict mid-segment left anterior descending lesions in acute coronary syndrome? A retrospective study

OBJECTIVES

Limited data are available regarding the predictive value of electrocardiographic T wave inversion in lead aVL for mid-segment left anterior descending (MLAD) lesions among patients with acute coronary syndrome (ACS).

SETTING

Retrospective single-centre study, using a prospectively-collected coronary angiography database from January 2012 to December 2013.

PARTICIPANTS

We included consecutive adult patients with ACS who underwent urgent percutaneous coronary intervention (PCI) within 24 h after arriving at the hospital. We excluded patients who did not undergo an ECG before PCI, patients with proximal MLAD occlusion and patients diagnosed with vasospastic angina.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was MLAD lesion >50%. The other outcome of interest was MLAD lesion as a cause of ACS. First, we evaluated the diagnostic values of T wave inversion in lead aVL regardless of other T wave changes for each outcome. Second, we evaluated the diagnostic values of isolated T wave inversion in lead aVL.

RESULTS

Overall, 219 patients were eligible for the analysis. T wave inversion in lead aVL regardless of other T wave changes had a sensitivity of 32.9%, specificity of 48.2%, positive predictive value of 27.6% and negative predictive value of 54.5% for predicting MLAD lesions. Isolated T wave inversion in lead aVL had a sensitivity of 9.8%, specificity of 86.9%, positive predictive value of 30.8% and negative predictive value of 61.7% for predicting MLAD lesions. These diagnostic values did not change materially when focusing on patients with MLAD lesion as the cause.

CONCLUSIONS

While T wave inversion in lead aVL regardless of other T wave changes had low diagnostic values for predicting MLAD lesions, isolated T wave inversion in lead aVL had a high specificity. Our inferences underscore the importance of a cautious interpretation of T wave inversion in lead aVL among patients with ACS.

Isolated T Wave Inversion in Lead aVL: An ECG Survey and a Case Report

Background. Computerized electrocardiogram (ECG) analysis has been of tremendous help for noncardiologists, but can we rely on it? The importance of ST depression and T wave inversions in lead aVL has not been emphasized and not well recognized across all specialties. Objective. This study's goal was to analyze if there is a discrepancy of interpretation by physicians from different specialties and a computer-generated ECG reading in regard to a TWI in lead aVL. Methods. In this multidisciplinary prospective study, a single ECG with isolated TWI in lead aVL that was interpreted by the computer as normal was given to all participants to interpret in writing. The readings by all physicians were compared by level of education and by specialty to one another and to the computer interpretation. Results. A total of 191 physicians participated in the study. Of the 191 physicians 48 (25.1%) identified and 143 (74.9%) did not identify the isolated TWI in lead aVL. Conclusion. Our study demonstrated that 74.9% did not recognize the abnormality. New and subtle ECG findings should be emphasized in their training so as not to miss significant findings that could cause morbidity and mortality.