https://orcid.org/0000-0002-1061-8096
A 58-year-old man with a history of hypertension, dyslipidaemia, and a known complete right bundle branch block (RBBB) presented to the emergency department with persistent chest pain at rest for 1 h. The pain radiated to his left arm and was accompanied by diaphoresis and nausea.
On examination, he was haemodynamically stable, euvolaemic, and well-perfused. Lung auscultation was clear, with no added sounds or crepitations. Heart sounds were rhythmic and normal, with no murmurs or pericardial rub.
A 12-lead electrocardiogram (ECG) was obtained and is shown below.
Question 1
Which of the following is NOT a characteristic finding in complete RBBB?
Normal R wave peak time in leads V5 and V6
RSR′ in leads V1 and V2
S wave duration greater than R wave duration in leads I and V6, or an S wave > 40 ms
Upright T waves in the right precordial leads and inverted T waves in the left precordial leads
R wave peak time > 50 ms in lead V1
Correct answer: D.
Discussion and explanation
In RBBB, T waves are typically discordant with the QRS complex, leading to inverted T waves in the right precordial leads and upright T waves in the left precordial leads. However, in this ECG, lead V2 shows a concordant upright T wave, which is atypical for isolated RBBB and may indicate an underlying pathological process.1 All other options describe classic RBBB findings.
Question 2
What is the next appropriate step in management?
Serial troponins at 0/1 h or 0/2 h and clinical decision based on results
Emergent coronary angiography
Load dual antiplatelet therapy
Initiate anticoagulation and perform CT angiography to rule out pulmonary embolism
Perform ischaemia testing to guide subsequent catheterization
Correct answer: B.
Discussion and explanation
The patient presents with persistent angina and an ECG showing ST elevation in leads I, aVL, and V2, along with reciprocal ST depression in the inferior leads, consistent with an acute ST-elevation myocardial infarction. Emergent coronary angiography is the most appropriate next step. While pre-treatment with aspirin and a P2Y12 inhibitor may be considered, it carries a class IIb recommendation in the 2023 ESC guidelines for acute coronary syndromes due to limited supporting evidence.2 Alternative options would lead to diagnostic delays or inappropriate management.
Question 3
Which coronary artery is most likely responsible for the infarction?
Diagonal branch of the left anterior descending artery (LAD)
Septal branch of the LAD
Obtuse marginal branch of the circumflex artery
Posterior interventricular artery
Posterolateral branch
Correct answer: A.
Discussion and explanation
The ECG shows a pre-existing RBBB with new ST elevation in leads I, aVL, and V2, along with a concordant upright T wave in V2 and reciprocal ST depression in lead III. This pattern, known as the South African Flag Sign, indicates a high lateral infarction, typically involving a diagonal branch (see Supplementary material online, Figure S1).3 Coronary angiography confirmed a 100% occlusion of the second diagonal branch (see Supplementary material online, Video S1). South African Flag Sign is rarely reported in RBBB patients, making this case notable. Recognizing this pattern is crucial for early intervention and improved patient outcomes.
Supplementary material
Supplementary material is available at European Heart Journal – Case Reports online.
Acknowledgements
The authors wish to express their gratitude to the Cardiology Department at Hospital de la Santa Creu i Sant Pau for their invaluable support and contribution to this work.
Consent: Direct written consent was obtained from the patient for the publication of this manuscript, in accordance with Committee of Publication Ethics (COPE) guidelines.
Funding: None declared.
Data availability
The data that support the findings of this study are available from the authors upon request.
References
Author notes
Conflict of interest: None declared.
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