Abstract
ECG is still the first diagnostic tool for coronary artery disease. It is possible to predict the localisation of affected vessel(s) through ST and T changes on ECG. Sometimes, reciprocal changes may be the only marker of acute myocardial ischaemia, as single T-wave inversion in lead aVL may represent a coronary artery lesion in the left anterior descending (LAD). A 49-year-old woman presented to the emergency department, with left-sided chest pain. Her initial ECG showed no ischaemic changes. On the third hour ECG there was T-wave inversion in leads aVL and V2, and troponin turned positive. Coronary angiography showed 90% mid-LAD occlusion. The importance of this case is that patients with ischaemic chest pain should be followed with serial ECG. Also, emergency physicians should be alert to identify new changes on ECG, as isolated T-wave inversion in lead aVL can be the only finding to take the patient into the catheterisation laboratory.
Background
ECG is still the first examination for coronary artery diseases in the changing and developing medical environment. As it is possible to predict the localisation of a coronary artery that is affected by means of diagnosing acute myocardial infarction (MI) through looking at the elevations of ST-segment in ECG, it is also possible to predict the localisation of the coronary artery that is affected by reciprocal ECG changes including ST depression and T-wave inversion.1 Sometimes, the reciprocal changes can be the sole sign of acute MI. Lead aVL change, which has recently proved to be accurate through case notifications, is one of them; however, it has still not attracted much notice. The only finding in ECG for acute MI might be ST-depression.2 Moreover, T-wave inversion in lead aVL might be the only sign of a left anterior descending artery (LAD) lesion.3 The purpose of this case is to emphasise the importance of isolated ST changes in lead aVL and to point out the benefits of encouraging emergency physicians to use early invasive intervention for these patients.
Case presentation
A 49-year-old woman with a history of hypertension was admitted to the emergency department, with chest pain and shortness of breath for 15 min. Her medical history included only hypertension. Vital signs were as follows—temperature 36.2°C, blood pressure 158/101 mm Hg, pulse 87/min and oxygen saturation 99%. She reported a substernal chest pain radiating to her left shoulder. Physical examination was unremarkable. Her initial ECG showed normal sinus rhythm (NSR) and no ischaemic changes (figure 1). In the laboratory investigation, the level of serum electrolytes, troponin value, complete blood count, coagulation and other biochemical values were normal. The thrombolysis in MI score determined for the patient was 1. There was no significant feature observed in her chest X-ray. A controlled ECG showing NSR and new onset T-wave inversion in lead aVL and V2 (figure 2.) Transthoracic echocardiography revealed left ventricular segmental contraction disability (apex hypokinetic) and the ejection fraction was 50%. Meanwhile, the control troponin value (3rd hour) was 0.39 ng/mL (normal interval 0–0.03 ng/mL). The patient was given acetylsalicylic acid, clopidogrel and unfractionated heparin and sent for emergency cardiac catheterisation. Angiography revealed a 90% mid-LAD and 50% ostial LAD lesions, and she received a stent (figures 3 and 4).
Figure 1.
Twelve-lead ECG at presentation showing normal sinus rhythm and no ischaemic change.
Figure 2.
Dynamic T-wave changes on ECG; T-wave inversions in leads aVL and V2.
Figure 3.
Coronary angiography showing mid-left anterior descending lesion (white arrow).
Figure 4.
Coronary angiography showing ostial left anterior descending occlusion (white arrow).
Discussion
ECG provides data for use in detecting acute coronary syndrome, the coronary arteries affected by the acute coronary syndrome and the severity of myocardial ischaemia. Sometimes it is possible to diagnose these using the first ECG, whereas other times it is diagnosed by repetitive ECG, as in this case.
Although immediate cardiac catheterisation is suggested for ST elevation MI (STEMI) in the guidelines, recently it has been suggested to have immediate cardiac catheterisation in case of de Winter's T-waves (symmetric T-waves with down-sloping ST depression in precordial derivations), left main coronary artery occlusion (ST elevation with common ST depression in aVR) and Wellens findings, which is regarded as the STEMI equivalent.4
The first marker for inferior MI might be a T-wave change in lead aVL; it might also be seen as the first finding in mid-LAD lesion. However, this important finding is not well-known and has not been put into practice.5
In a study by Hassen et al,6 an ECG, including isolated T-wave inversion in lead aVL, was shown to 191 doctors, and 143 of them (74.9%) interpreted it as normal.
Farhan et al7 analysed ECGs of 191 patients with chronic stable angina having cardiac catheterisation; the authors stated that only 14.1% of the patients had isolated T-wave inversion in lead aVL and emphasised that it has high-predictive value for showing mid-LAD lesions.
Isolated T-wave inversion in lead aVL is not always a pathological finding, it might appear as a normal finding. The incidence in the general population is not well known, however, it is reported to be 10–20% in the Caucasian population in Scotland.8 Therefore, it would be better to use certain kinds of qualitative and quantitative definitions in order to recognise whether T-wave inversion is normal or pathological. For example, it is stated that Pardee T-waves (refer to minimal ST segment elevation at onset and mid-portion ≥0.02 mV above isoelectric line and T-wave inversion ≥0.06 mV in one of the precordial leads V1–V6), defined by Pardee, have high predictive value for ischaemic heart diseases.9
One of the points to be emphasised in this case is the importance of repetitive ECG for those patients describing chest pain, especially with ischaemic features, even if the first ECG and/or enzymes were observed to be normal. Combination of the clinical status, risk factors and patients' symptoms with T-wave changes may suggest ischaemic heart disease.
Learning points.
ECG is still the first diagnostic tool for coronary artery disease and dynamic changes in ECG are important in diagnosis of myocardial ischaemia.
It is possible to predict the localisation of affected vessel(s) through ST and T changes on ECG. Sometimes, reciprocal changes may be the only marker of acute myocardial ischaemia.
The first reciprocal marker for inferior wall myocardial infarction or mid-left anterior descending lesion may be T-wave change in lead aVL.
It would be better to reassess the patients by repetitive ECG and enzymes since there might be isolated T-wave inversion in lead aVL even in the normal population.
Footnotes
Contributors: RA conceived of the case. RA and FD initiated the case design and OOO and EUA helped with implementation. All the authors approved the final manuscript.
Competing interests: None declared.
Patient consent: Obtained.
Provenance and peer review: Not commissioned; externally peer reviewed.
References
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