Cardiovascular Journal of Africa: Vol 31 No 6 (November/December 2020)

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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 31, No 6, November/December 2020 AFRICA 331
Posterior infarction: a STEMI easily missed
Lina Hähnle, Charle Viljoen, Julian Hoevelmann, Robert Gill, Ashley Chin
Abstract
Anterior ST-segment depression encompasses important
differential diagnoses, including ST-segment elevation
myocardial infarction, non-ST-segment elevation myocardial
infarction and pulmonary embolism. Diagnostic accuracy is
crucial, as this has important therapeutic implications. This
ECG case report reviews the electrocardiographic changes
seen in patients with chest pain and anterior ST-segment
depression.
Keywords: ECG, STEMI, NSTEMI, pulmonary embolism
DOI: 10.5830/CVJA-2020-059
A 65-year-old woman with a 30 pack-year smoking history,
hypertension, dyslipidaemia and type 2 diabetes mellitus woke
up with severe central crushing chest pain and autonomic
symptoms. She was rushed to her nearest emergency centre
where a 12-lead electrocardiogram (ECG) was performed (Fig.
1). This showed a sinus tachycardia, with narrow QRS complexes
and no Q waves. The ST-segment depression in the anterior leads
(V1 to V4) prompted the attending physician to acquire another
ECG, which extended the recording to include posterior leads
(V7, V8 and V9) (Fig. 2). This showed ST-segment elevation
in V7 to V9, confirming the diagnosis of an acute posterior
ST-segment elevation myocardial infarction (STEMI).
The patient was given loading doses of dual antiplatelet
therapy and taken for primary percutaneous coronary
intervention (PCI). Coronary angiography showed an acute
occlusion of the proximal circumflex artery (LCx), which was the
culprit lesion. The patient also had severe coronary artery disease
in both the right coronary artery and the left anterior descending
artery (LAD). (Fig. 3A, B). A drug-eluting stent (DES) was
inserted in the LCx to treat the culprit lesion, resulting in good
reflow. The patient was stabilised in the coronary care unit and
discharged on guideline-directed medical therapy. Percutaneous
intervention of the non-culprit lesions was planned as an elective
procedure.
Discussion
All patients who present with chest pain should have a 12-lead
ECG.1 The ECG should be scrutinised for any features that
might suggest myocardial ischaemia, infarction or pulmonary
embolism (Table 1). Prompt recognition of these life-threatening
conditions will aid in the institution of timeous and appropriate
revascularisation therapy.1,2
Hatter Institute for Cardiovascular Research in Africa,
University of Cape Town, Cape Town, South Africa
Lina Hähnle, BSc, MB BCh
Charle Viljoen, MB ChB, MMed, FCP (SA),
Julian Hoevelmann, MD
Division of Cardiology, University of Cape Town, Cape
Town, South Africa
Charle Viljoen, MB ChB, MMed, FCP (SA)
Ashley Chin, MB ChB, FCP (SA), MPhil
Department of Internal Medicine III, Klinik Für Innere
Medizin III, Kardiologie, Angiologie, Internistische
Intensivmedizin, Universitätsklinikum des Saarlandes,
Saarland University, Homburg, Germany
Julian Hoevelmann, MD
Department of Medicine, University of Cape Town, Cape
Town, South Africa
Robert Gill, MB ChB, Dip HIV Man (CMSA), FCP (SA)
ECG Series
Table 1. ECG features of acute posterior STEMI, NSTEMI and acute PE
Acute posterior STEMI NSTEMI Acute PE
Q wave in III Only present if inferior STEMI involvement Should not be present May be present as part of SIQIIIT III
Dominant R in V1 Usually present and develops over days Should not be present Only present if RVH developed from chronic
pulmonary thromboembolic disease. Severe PE
may cause incomplete or complete RBBB.
S wave in I Should not be present Should not be present May be present as part of SIQIIIT III
ST-segment depression V1–V3 Usually present May be present May be present
ST-segment elevation V7–V9 Usually present Should not be present Should not be present
ST-segment elevation elsewhere Inferior ST-segment elevation may be present Should not be present Should not be present
T-wave inversion in V1–V3 May be present in the acute setting, followed
by upright T wave in V1
May be present (Wellens’ pattern) May be present
T-wave inversion in III May be present May be present May be present as part of SIQIIIT III
STEMI, ST-segment elevation myocardial infarction; NSTEMI, non-ST-segment elevation myocardial infarction; PE, pulmonary embolism; RBBB, right bundle
branch block; RVH, right ventricular hypertrophy;.