62-Year-Old With Acute Dyspnea

Published on September 27, 2026

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Differential Diagnosis

Hyperkalemia
Non-ST-segment elevation myocardial infarction (NSTEMI)
Wellens syndrome
Pulmonary embolism with acute right ventricular strain
Hypertrophic cardiomyopathy

Diagnosis

The diagnosis in this case is pulmonary embolism with acute right ventricular strain. The ECG demonstrates sinus tachycardia at approximately 110 beats per minute with a normal axis and normal intervals. There is ST-segment elevation of approximately 1 millimeter in leads III and aVF with reciprocal ST-segment depression in lead aVL—a pattern consistent with inferior ST-segment elevation myocardial infarction (STEMI). In addition, there are T wave inversions in the right precordial leads V1 through V3, with deep T wave inversions visible throughout the V1 rhythm strip, as well as an S1Q3T3 pattern, all consistent with acute right ventricular strain.

Discussion

This case demonstrates an interesting phenomenon: a pulmonary embolism with right ventricular strain masquerading as an inferior STEMI. The ST-segment elevation in leads III and aVF with reciprocal ST-segment depression in lead aVL should prompt activation of the cardiac catheterization laboratory and/or immediate transfer to a cath-capable facility; however, there are additional clues that point to an alternative diagnosis.

While T wave inversions are often cited as a finding in acute coronary syndrome, alternative causes also exist. Electrocardiographic findings that support the diagnosis of pulmonary embolism over acute coronary syndrome include T wave inversions in leads V1 through V3, inferior T wave inversions, and an S wave in lead I. One study suggests the pattern of simultaneous T wave inversions in lead III and V1 yields a specificity of 99% for pulmonary embolism.¹ This ECG not only suggests pulmonary embolism but identifies this patient as high risk.^2-3 Additionally, the presenting symptom (acute dyspnea and hypoxia rather than chest pain) points to acute pulmonary embolism rather than acute coronary syndrome.

A large pulmonary embolism can mimic a STEMI by increasing right ventricular wall tension and oxygen demand. Because the right coronary artery supplies the inferior wall of the left ventricle in most patients (right-dominant circulation), right coronary artery hypoperfusion in pulmonary embolism can produce inferior ECG changes that range from T wave inversion to ST-segment depression to frank ST-segment elevation, as in this case.⁴ Regardless, immediate transfer to a cardiac care center is warranted.

Wellens syndrome refers to deeply inverted or biphasic T waves in leads V2 and V3 in a patient who is pain-free at the time of the ECG and reflects critical left anterior descending artery stenosis. This patient’s presentation of acute dyspnea, tachycardia, and hypoxia does not fit. Hypertrophic cardiomyopathy produces deep asymmetric T wave inversions typically in the lateral leads often with voltage criteria for left ventricular hypertrophy. Neither is present on this ECG, and hypertrophic cardiomyopathy does not present acutely over hours. Findings of hyperkalemia—peaked T waves, bradycardia, junctional rhythm, widened QRS complex—are not visualized on this ECG.

Urgent care management of a suspected pulmonary embolism is focused on hemodynamic stabilization and immediate transfer. A thorough history should screen for symptoms of hypoperfusion, such as syncope or altered mental status, and risk factors (such as recent surgery, malignancy, or prolonged immobilization). Initial steps include establishing intravenous access, placing the patient on continuous cardiac monitoring, and administering supplemental oxygen if hypoxic. Hemodynamically unstable patients (ie, presenting with hypotension or shock) require immediate resuscitation and transfer via advanced life support to the nearest emergency department.⁵

What to Look For

Pulmonary embolism can produce inferior ST-segment elevation that mimics STEMI.
Simultaneous T wave inversions in the inferior (II, III, aVF) and right-precordial leads (V1–V3) strongly favor pulmonary embolism over acute coronary syndrome.
Sinus tachycardia is the most common ECG abnormality in pulmonary embolism.
The classic S1Q3T3 pattern is specific but has low sensitivity (<20%) for pulmonary embolism and represents acute right ventricular strain.

Pearls For Initial Management, Considerations For Transfer

Establish intravenous access, initiate continuous cardiac monitoring, and administer supplemental oxygen immediately if the patient is hypoxic.
Perform a rapid screening history for risk factors of deep vein thrombosis and pulmonary embolism, such as recent surgery or immobilization.
Transfer the patient immediately via advanced life support to the nearest emergency department if the patient is hemodynamically unstable or if there is high clinical suspicion for pulmonary embolism.
Do not delay transfer to obtain outpatient imaging or blood work when a massive pulmonary embolism is clinically suspected.

References

Kosuge M, Kimura K, Ishikawa T, et al. Electrocardiographic differentiation between acute pulmonary embolism and acute coronary syndromes on the basis of negative T waves. Am J Cardiol. 2007;99(6):817–821. doi:10.1016/j.amjcard.2006.10.043
Kosuge M, Kimura K, Ishikawa T, et al. Prognostic significance of inverted T waves in patients with acute pulmonary embolism. Circ J. 2006;70(6):750–755. doi:10.1253/circj.70.750
Kukla P, McIntyre WF, Fijorek K, et al. T-wave inversion in patients with acute pulmonary embolism: prognostic value. Heart Lung. 2015;44(1):68–71. doi:10.1016/j.hrtlng.2014.10.003
Alsidawi S, Effat M, Rongkavilit C. Massive pulmonary embolism with ST elevation in the inferior leads and other interesting ECG findings. J Biomed Graph Comput. 2013;3(2):44–47. doi:10.5430/jbgc.v3n2p44
Konstantinides SV, Meyer G, Becattini C, et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism developed in collaboration with the European Respiratory Society (ERS). Eur Heart J. 2020;41(4):543–603. doi:10.1093/eurheartj/ehz731

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