Pulmonary embolism mimicking acute myocardial infarction: a case report and review of literature
Saida Zelfani1,&, Hela Manai1, Saoussen Laabidi1, Abir Wahabi1, Sara Akeri1, Mounir Daghfous1
1Pre Hospital Emergency Department (SAMU 01), Emergency Medical Help Center of Tunis, Tunis, Tunisia
Saida Zelfani, Pre Hospital Emergency Department (SAMU 01), Emergency Medical Help Center of Tunis, Tunis, Tunisia
The diagnosis of pulmonary thromboembolism (PTE) with changes shown by electrocardiography (ECG) is a challenge in the clinical practice due to rare pathognomonic findings. We report the case of a 37-year old woman managed in out of hospital sitting for a chest pain. Electrocardiogram was suggestive of antero-septal acute myocardial infarction (AMI). Catheterization revealed non occlusive coronary disease. Transthoracic echocardiography showed an elevated pulmonary and right heart pressures. Computed tomography pulmonary angiography confirmed the diagnosis of bilateral pulmonary embolism. PTE with ECG changes should be considered in the differential diagnosis of AMI, particularly in young patients with chest pain and ST segment elevation suggestive of acute coronary syndrome.
The ST segment elevation represents common electric sign of acute transmural ischemia caused by an occlusion of an epicardial coronary artery by a blood clot. Especially in pre hospital care and without other investigations, urgent therapy for patients with chest pain and ST elevation must be considered to reanalyze the occluded artery by percutaneous coronary intervention or fibrinolysis when cat lab is unavailable or far away.
Symptoms of pulmonary thromboembolism (PTE) and acute myocardial infarction (AMI) can be similar, including acute dyspnea, chest pain, syncope and palpitations. Physical examination is nonspecific and cannot reliably distinguish these two diagnoses. Electrocardiogram (ECG) may be helpful for the diagnosis of PE but its limited by his sensitivity and specificity [1-3]. Although several ECG changes can be observed in the acute phase of PTE, ST segment elevation is a rare finding [4-6].
We report a case of woman who had dynamic ST segment elevation suggestive of antero-septal AMI that proved to be bilateral PTE.
Patient and observation
A 37-year-old woman, without past medical history, presented to
emergency room in primary center, complaining of chest pain, acute
coronary syndrome was suspected. Our emergency medical system received
call for this
patient and activated pre hospital emergency team for transfer.
The patient suffered from continuous acute two hours before our
intervention. She doesn't
have previous history of similar episode. No previous history of
coronary artery disease, peripheral vascular disease, stroke, malignancy,
thromboembolism was reported. There was no family history of thromboembolic
disease. Physical examination revealed: a regular pulse rate 110
beats/min, blood pressure was 100/65mmHg, respiratory rate wa 20
saturation was 95% at room air and 99% with 2l/min oxygen via nasal
canula and temperature was 37°C. Cardiac auscultation was normal. There
were no congestive neck veins. An initial ECG showed a sinus rhythm,
an ST segment
elevation of 2 mm in V2 and V3 without other anomalies (Figure
The initial diagnosis of antero-septal AMI was established. After initiating
treatment by Aspirin (250 mg), Clopidogrel (300 mg) and intravenous
heparin, the patient was transferred to cat lab. Twenty minutes
later a second ECG
showed a right bundle branch block (RBBB) with disappearance of
ST segment elevation on precordial leads (Figure
Coronary angiography performed forty five minutes later, however showed normal
coronary arteries without stenosis. Transthoracic echocardiography
(TTE) revealed right ventricular dilatation and elevated pulmonary
(HTAP = 60 mmHg). Computed tomography pulmonary angiography concluded
to proximal bilateral pulmonary embolism with dilated right ventricle
septum (Figure 3).
A Doppler ultrasound of the lower extremities did not show any
finding compatible with deep venous thrombosis. An intravenous
heparin was initiated with good
outcome. An etiological investigation of thromboembolic disease
demonstrated the presence of deficiency of protein C. Oral anticoagulation
before discharge from the hospital. The patient was doing well
at 3 months of follow-up.
The ECG still has a major role in diagnosing and triage of patients
presenting with chest pain . The current American
college of cardiology/American heart association (ACC/AHA) guidelines for
STEMI recommend that patients with suggestive symptoms of myocardial ischemia
who have ST segment elevation at the J point (in 2 contiguous leads or more
of 0.2 mV or more in males or 0.15 mV or more in women in leads V2V3 and/o
of 0.1 mV or more in all other leads in threshold) should undergo immediate
reperfusion therapy .
Otto found that 63 patients among 123 (59%) with chest pain and ST elevation
in pre hospital care had diagnosis rather than AMI .
In another study, Brady found that 157 patients among 212 (74%) presenting
with chest pain had elevation of the ST segment due to non ischemic etiologies.
This condition is challenging for emergency physicians and even cardiologists.
The differential diagnosis of elevation of the ST segment is wide including
conditions with secondary of the myocardium (for exemple dissection of aortic
wall), pre existing ST elevation without acute ischemia and instances with
new ST with chest pain and without evidence of ischemia (for example myocarditis
or pericarditis, pulmonary embolism, electrolyte imbalance, rate related
repolarization changes etc) . Wang described twelve
conditions of mimicking STEMI (Table
1) and highlighted the electrocardiographic clues that can be used
to differentiated them from AMI . Some creteria
can be useful to differentiate STEMI from the elevation of ST due to non
ischemic etiologies (NISTE). The most sensitive is reciprocal changes, it
support the diagnosis of AMI with a positive predictive value more than
90%. Reciprocal changes were not present in our case. Due to the presence
of atypical ECG changes for acute PTE in our patient, AMI was considered
initially in the differential diagnosis and a coronary angiogram was performed
before other non invasive tests. Other evaluations like echocardiography
could be helpful in this case. TTE is a readily available bedside test that
can be performed in the emergency department on admission and is helpful
to differentiate massive PTE and anteroseptal AMI. The ST segment changes
in the ECG of this case were similar to those of previous report .
However, ST segment elevation is not among the usual findings associated
with PE. It probably occurs due to acute right ventricular strain and elevated
pressures resulting from a sub massive or massive PE .
Chia et al.  described ECG findings of ST segment
elevation and a qs or qr pattern in 3 patients with PE in the right precordial
leads those abnormalities were mostly normalized within 6 weeks due to the transient
nature of ECG abnormalities.
Emergency physician must be aware of the importance to differentiate between STEMI and NISTE in patients presenting with symptoms suggestive of MI in order to avoid unsafe treatment. Chest pain is common in PE and a sensible ECG analyze can detect specific signs.
The authors declare no competing interests.
All authors contributed to this work. They also read and approved the final version of this work.
Table and figures
Table 1: etiologies of ST elevation according to Wang (11)
Figure 1: electrocardiogram shows ST-segment elevation of 2 mm in leads V2 and V3
Figure 2: electrocardiogram shows a right bundle branch block (RBBB) in leads V1, V2 and V3
Figure 3: chest CT scan
showing proximal pulmonary embolism (A) and dilated right ventricle (B)
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