Lead aVR: Importance of the "Forgotten 12th Lead" in Patients With ACS

[AnthonyM83]

http://www.medscape.com/viewarticle/589781...mp;uac=106044SV

Lead aVR: Importance of the "Forgotten 12th Lead" in Patients With ACS

In recent years, more studies have demonstrated the importance of lead aVR during the analysis of the 12-lead electrocardiogram (ECG) in patients with acute coronary syndrome (ACS).

(Continued at the site...Easy read, like two paragraphs plus an abstract)

[FireMedic65]

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[scott33]

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Same here. Can you copy and paste please

[wrmedic82]

Introduction

In recent years, more studies have demonstrated the importance of lead aVR during the analysis of the 12-lead electrocardiogram (ECG) in patients with acute coronary syndrome (ACS). These studies have indicated that lead aVR is a strong predictor of left main coronary artery (LMCA) occlusion when used in isolation[1] or in conjunction with other leads.[2] Studies have indicated that the presence of simultaneous ST-segment elevation (STE) in leads aVR + aVL[3] or the presence of STE in aVR that exceeds the amount of STE in lead V1[4,5] is highly specific for LMCA occlusion in patients with ACS. Other studies have discussed STE in lead aVR in less specific terms, simply citing that this finding is indicative of either LMCA occlusion or left anterior artery occlusion,[6,7] or indicative of either LMCA occlusion or triple-vessel disease.[8] The magnitude of STE in lead aVR that is considered significant is inconsistent among these articles; some articles have evaluated any STE in aVR, whereas others have focused on STE greater than 1 mm. This difference may account for the varying specificities for LMCA involvement. Regardless, the literature continues to show with increasing consistency that STE in lead aVR in patients with ACS is associated with more ominous coronary occlusions. Patients with LMCA occlusions, left anterior artery occlusions, or triple-vessel occlusions have a worse prognosis, requiring more aggressive immediate therapy and often bypass surgery. Emergency physicians who find ECG predictors of any of these 3 conditions in their patients with ACS (whether ST-segment elevation myocardial infarction [sTEMI] or non-STE ACS) would be prudent to mobilize resources for rapid invasive therapy. Additionally, because many of these patients will require coronary artery bypass grafting, it certainly seems advisable to withhold clopidogrel.[4] Below is a summary of one more study that adds to the literature indicating that STE in lead aVR predicts more pronounced coronary occlusions and a worse prognosis.

Admission ST-Segment Elevation in Lead aVR as the Factor Improving Complex Risk Stratification in Acute Coronary Syndromes

Szymanski FM, Grabowski M, Filipiak KJ, Karpinski G, Opolski G

Am J Emerg Med. 2008;26:408-412

Summary

Szymanski and colleagues evaluated the association of STE in lead aVR with mortality. The investigators assessed 205 consecutive patients with non-STEMI ACS for STE in lead aVR of at least 0.5 mm. Patients were divided into 3 risk groups on the basis of their Thrombolysis in Myocardial Infarction (TIMI) risk score,[9] a validated ACS scoring system that is used to gauge 14-day risk for adverse outcome in patients admitted with ACS. Low-risk patients had 0-2 points; intermediate-risk patients had 3-4 points; and high-risk patients had 5-7 points on the TIMI scale. STE in lead aVR was found in 114 patients. The researchers found that the presence of STE in aVR was a strong and independent predictor of 30-day mortality (odds ratio, 7.8). During this 30-day period, 18 patients (8.8%) died. Of those who died, 16 of 18 (88.9%) had STE in aVR vs 98 of 187 (52.4%) of the survivors who had STE in aVR. Mortality also increased with the severity of STE in aVR. Mortality was 2 of 91 (2.2%) for patients without STE in aVR, 8 of 74 (10.8%) for patients with STE of 0.5 mm, 4 of 29 (13.8%) for patients with STE of 1 mm, 2 of 9 (22.2%) for patients with STE of 1.5-2.5 mm, and 2 of 4 (50%) for patients with STE of ≥ 3 mm. The increases in mortality were statistically significant.

Viewpoint

When considering the TIMI risk stratification scores, the researchers discovered that patients with STE in aVR, when compared with patients without STE in aVR, had higher death rates in the low-risk (18.5% vs 0%) and intermediate-risk groups (15.5% vs 2.6%). The study authors concluded that STE in lead aVR in patients with ACS was a good predictor of short-term mortality and could be used synergistically with TIMI scores for early stratification of risk. The takeaway point is simple: When patients with ACS, including non-STE ACS, demonstrate STE in lead aVR, the aggressiveness of early management must be increased. These patients have more complex coronary lesions and will likely benefit from earlier invasive therapy.

Abstract

This study aimed to analyze the prognostic value of the presence of ST elevation in lead aVR [aVR(+)] in initial standard electrocardiogram (ECG) performed on admission in combination with clinical variables and Thrombolysis in Myocardial Infarction (TIMI) risk score for unstable angina/non-ST-elevation myocardial infarction (UA/NSTEMI). In 205 consecutive patients with UA/NSTEMI, we retrospectively evaluated admission ECG for aVR(+) of more than 0.5 mm. With the use of multivariate analysis, admission aVR(+) was found to be a strong and independent predictor of 30-day mortality. Mortality also increased with the severity of aVR(+): 2.2%, 10.8%, 13.8%, 22.2%, 50% (P value for trend <.0001). In prespecified low-risk groups by clinical factors, those with aVR(+) had higher death rates than those without aVR(+): 16.1% vs 2.2% (P = .04), 13.9% vs 1.1% (P = .001), 12.4% vs 1.1% (P = .002), 9.6% vs 1.2% (P = .02), and 6.7% vs 0% (P = .05) for patients with negative troponin, heart rate of 110 beats per minute or less, systolic blood pressure greater than 90 mm Hg, Killip I class on admission, and age 70 years or younger, respectively. Patients with aVR(+) compared to patients without aVR(+) had higher death rates in the low- and intermediate-risk groups by TIMI risk score. Our findings suggest that aVR(+) has significant prognostic value in patients with UA/NSTEMI and may provide an additional prognostic value to the conventional cardiovascular risk factor, particularly in patients in the low-risk and intermediate-risk groups.

Edited April 15, 2009 by wrmedic82

[akroeze]

Interesting.

From a field treatment perspective does this change anything for us? Should we be calling STEMI alerts possibly for isolated aVR elevation?

[AnthonyM83]

I don't think we can change the STEMI criteria, but it definitely means we should take that patient very seriously and be aggressive in timely medication administration, quick off-scene time, and constant EKG monitoring. The study just correlates with 30-day mortality, so they're not necessarily going to croak on you...but you should do whatever is possible to limit heart damage (ASA, decrease myocardial O2 demand, ER notification).