Tag Archives: ECG

Normal ECG still doesn't rule out PE

ECGs from a prospective study of patients in the ED with suspected pulmonary embolism were studied to identify the relative frequency of ECG features of pulmonary hypertension. For a patient to be eligible for enrollment, a physician was required to have sufficient suspicion for pulmonary embolism to order objective diagnostic testing in the ED. Such testing included D-dimer measurement, computed tomography pulmonary angiography, ventilation/perfusion scanning, or venous ultrasonography.
ECGs were done in 6049 patients, 354 (5.9%) of whom were diagnosed with pulmonary embolism. The frequency, positive likelihood ratio (LR+) and 95% confidence interval (CI) of each predictor were as follows:

  • S1Q3T3 8.5% with pulmonary embolism versus 3.3% without pulmonary embolism (LR+ 3.7; 95% CI 2.5 to 5.4)
  • nonsinus rhythm, 23.5% versus 16.6% (LR+ 1.4; 95% CI 1.2 to 1.7)
  • inverted T waves in V1 to V2, 14.4% versus 8.1% (LR+ 1.8; 95% CI 1.3 to 2.3)
  • inversion in V1 to V3, 10.5% versus 4.0% (LR+ 2.6; 95% CI 1.9 to 3.6)
  • inversion in V1 to V4, 7.3% versus 2.0% (LR+ 3.7; 95% CI 2.4 to 5.5)
  • incomplete right bundle branch block, 4.8% versus 2.8% (LR+ 1.7; 95% CI 1.0 to 2.7)
  • tachycardia (pulse rate>100 beats/min), 28.8% versus 15.7% (LR+ 1.8; 95% CI 1.5 to 2.2).

The authors point out that the study may be subject to reporting bias or incorporation bias because those patients with ECG abnormalities may have then been more likely to undergo further evaluation for PE.
Overall, they summarise that the main findings were that the S1Q3T3 pattern and precordial T-wave inversions had the highest LR(+) values with lower-limit 95% CIs above unity, whether or not the patient had preexisting cardiopulmonary disease, but emphasise that the sensitivities of each of these findings were low, and clinicians should not decrease their suspicion for pulmonary embolism according to their absence.
Likelihood ratios and specificities were similar when patients with previous cardiopulmonary disease were excluded from analysis.
12-Lead ECG Findings of Pulmonary Hypertension Occur More Frequently in Emergency Department Patients With Pulmonary Embolism Than in Patients Without Pulmonary Embolism
Ann Emerg Med. 2010 Apr;55(4):331-5

80 lead ECG increases AMI detection – so what?

The 80-lead ECG is more sensitive than a 12 lead ECG for detecting infarcts in the posterior, right, inferior, and high lateral areas of the heart.
80-lead ECG body surface mapping was applied to 1830 patients in the emergency department with moderate to high risk chest pain. 12 lead ECG detected STEMI in 91 patients and an additional 25 patients had 80-lead-only STEMI.

The authors and an editorialist point out some interesting issues and unanswered questions regarding the application of this technology:

  • Since almost all of the 80-lead-only STEMI patients had an elevated troponin, is this just another way of diagnosing NSTEMI?
  • Since there are no convincing data demonstrating a benefit from immediate therapy of NSTEMI, would the earlier detection improve outcome?
  • Angiographic findings in the 80-lead-only STEMI group showed similar lesions to 12-lead STEMI patients, with more frequent involvement of posterior (left circumflex) and right ventricular (right coronary artery) regions
  • Is the increase in sensitivity offered by the 80-lead ECG accompanied by a decrease in specificity?

More research is needed – preferably in a randomised controlled trial – before this interesting technology is rolled out in emergency departments
Acute detection of ST-elevation myocardial infarction missed on standard 12-Lead ECG with a novel 80-lead real-time digital body surface map: primary results from the multicenter OCCULT MI trial.
Ann Emerg Med. 2009 Dec;54(6):779-788
The 80-lead ECG: more expensive NSTEMI or Occult STEMI
Ann Emerg Med. 2009 Dec;54(6):789-90

Characteristic ECG signs of LAD occlusion without ST elevation

In a single centre observational study over 10 years of patients undergoing acute PCI of the left anterior descending (LAD) artery, 35 of 1890 (2%) had a distinct non-ST elevation ECG pattern.
The ECG showed ST-segment depression at the J-point of at least 1 mm in the precordial leads with upsloping ST-segments continuing into tall, symmetrical T-waves. Patients also showed a mean J-point elevation of approximately 0.5 mm in lead aVR.
This novel ECG pattern resolved after reperfusion in all included patients.
The authors caution that these electrocardiographic changes may be missed or misdiagnosed as reversible ischaemia, which might substantially delay the transportation to a PCI centre or the start of reperfusion therapy
The authors conclude: “It is important for cardiologists and emergency care physicians to recognise this distinct ECG pattern, so they can triage such patients for immediate reperfusion therapy.”

Image from Dr Smith's ECG Blog

Persistent precordial “hyperacute” T-waves signify proximal left anterior descending artery occlusion
Heart. 2009 Oct;95(20):1701-6

Myocardial infarction not so common in LBBB?

An observational cohort study of 7937 ED visits by patients presenting with chest pain or ‘ischemic equivalent’ (shortness of breath for which ACS was considered a possible cause) was done to examine the relationship between left bundle branch block (LBBB) on the ECG and the incidence of acute myocardial infarction (AMI). No difference was observed in the rates of AMI in patients with new or presumed new LBBB, old LBBB, and no LBBB. The authors suggest that this large cohort of undifferentiated ED patients may be more reflective of the true prevalence of AMI in LBBB (7.3% in this study) and question the appropriateness of a liberal fibrinolytic strategy for such patients. Another argument for primary PCI?
Lack of association between left bundle-branch block and acute myocardial infarction in symptomatic ED patients
Am J Emerg Med. 2009 Oct;27(8):916-21