Terminal QRS distortion is present in anterior myocardial infarction but absent in early repolarization

Lee. @smithECGBlog. The American Journal of Emergency Medicine;2016;34(11):2182-2185

Clinical Question

• In patients with benign early repolarisation, is there the absence of terminal QRS distortion on the ECG?

Background

• For patients who present with chest pain, it can be difficult to distinguish between ECG findings of benign early repolarisation (BER) and left anterior descending artery occlusion (LADO)
• Terminal QRS distortion has been reported to be present in a number of patients presenting with LADO
• This trial investigated whether terminal QRS distortion was also present in patients with BER

Design

• Retrospective observational cohort study
• Secondary analysis
• Terminal QRS distortion defined as the absence of both of the following in V2 and/or V3
  • S wave
    • Any deflection at the end of the R wave that dipped below the level of the PQ junction
  • J wave
    • Any positive deflection (notching or slurring) above the level of the ST segment at the J point
• If patient had multiple ECGs only 1st ECG analysed
• 2 reviewers reported ECGs, not blinded to study objectives

Setting

• Single centre, USA
• Data collected from 2003 – 2005

Population

• Inclusion:
  • Patients presented to ED with chest pain
  • Admitted and ruled out for MI with serial troponins – 3 serial negative Troponin I (all below the reference value)
  • Had cardiologist confirmed interpretation of ER on the ECG
• Exclusion:
  • <1mm ST elevation in any of leads V2 – V4
• 242 patients found to have early repolorisation and a clinical picture of non-ischaemic chest pain
• 71 patients excluded as <1mm ST elevation
• Mean age 38 years
• 86% male

Outcome

• Primary outcome:
  • Terminal QRS distortion was absent in 100% of patients with benign early repolorisation (95% CI 97.8-100%)
• Secondary outcomes: In patients with BER
  • S wave absent in
    • 0.6% in lead V2
    • 9% in lead V3
  • J wave absent in
    • 95% in lead V2
    • 83% in lead V3
• When a J wave was present the S wave was significantly smaller amplitude
  • Median S wave amplitude with J wave present vs without J wave present
    • V2: 4 vs 14.5mm, P=0.004
    • V3: 0 vs 9mm, P<0.0001

Authors’ Conclusions

• The presence of any terminal QRS distortion was 100% specific to acute MI

Strengths

• Use of two reviewers
• All patients included were admitted and had serial troponins
• Clearly defined criteria for assessing terminal QRS distortion

Weaknesses

• Retrospective
• Single centre
• Did not investigate patients presenting with other causes of ST elevation e.g. pericarditis, left ventricular hypertrophy
• ECG readers were not blinded to study objective
• Small data set compared to the large number of ECGs that are taken daily worldwide
• Full patient demographics not available, and at first glance it is a limited data set (average age 38, and 86% male)- as age, sex, body habitus and ethnicity may all contribute to ECG patterns, a limited pool of patients could have biased the results

The Bottom Line

• In patients that have benign early repolorisation there is the absence of terminal QRS distortion
• The vast majority of patients with BER had a S wave that was present in V2 and/or V3; and those that did not have a S wave always had a J wave
• If a patient has an absence of a S wave and a J wave in V2/V3 then the diagnosis of BER is very unlikely and based on previous research the diagnosis of acute MI should strongly be considered

External Links

• [article] Terminal QRS distortion is present in anterior myocardial infarction but absent in early repolarisation 
• [further reading] Best Explanation of Terminal QRS Distortion in Diagnosis of Electrocardiographically Subtle LAD Occlusion
• [further reading] Dr Smith’s ECG Blog

Metadata

Summary author: @davidslessor
Summary date: 16/02/22

Peer reviewer: Segun Olusanya