OVERVIEW
Please submit letters for the editor's consideration within three weeks of receipt of Clinical Medicine. Letters should ideally be limited to 350 words, and sent by email to: clinicalmedicine{at}rcplondon.ac.uk
Editor – We read with great interest the letter from Gottschalk et al, and we would like to thank them for their interest in our review article. We are grateful to the authors for drawing our attention to the terminology ‘Brugada phenocopy’ (BrP) and their work on BrP.
Riera et al 1 introduced the term ‘Brugada phenocopy’ to describe the Brugada pattern that can be linked to a pre-existing and well-known condition. They chose this term based on a previous definition of phenocopy: ‘an environmental condition that imitates (copies) one produced by a gene’. The authors described a classic Brugada-type 1 ECG pattern in a patient intoxicated with propofol. In this particular case, the environmental condition was the infusion of propofol that triggered this particular ECG manifestation.
BrP are clinical entities that are etiologically distinct from true congenital BrS. BrP are defined by ECG patterns that are identical to BrS but are elicited by various clinical circumstances.
There are few key features that helps in distinguishing between BrP and the true congenital BrS. 2 First, patients with BrP have a reversible underlying condition, such as adrenal insufficiency, hypokalemia or myocardial ischemia, that elicits or induces the Brugada ECG pattern. There is prompt normalisation of the ECG once this underlying condition is resolved. This is contrary to true congenital BrS where the ECG manifestations are unmasked by sodium channel blockers, vagotonic agents, febrile states and various metabolic conditions. Second, patients with BrP have a low clinical pretest probability of true congenital BrS, as opposed to a high clinical pretest probability in patients with true congenital BrS who have a documented personal history of cardiac arrest, non-vagal syncope or a family history of sudden cardiac death. 3 Third, patients with BrP have a negative provocative challenge with a sodium channel blocker, while those with true congenital BrS have a positive provocative challenge. 2
Gottschalk et al recently developed a morphological classification system which divides BrP into type-1 and type-2 BrP according to the manifested ECG pattern. The type-1 BrP is identical to a coved or type-1 Brugada ECG pattern and the type-2 BrP is identical to a saddleback or type-2 Brugada ECG pattern. 4–6 These two categories include A, B, and C qualifiers. Class A includes BrP that have met all mandatory diagnostic criteria, including negative provocative challenge with a sodium channel blocker. Class B includes highly suspected BrP; however, not all mandatory diagnostic criteria are complete. Class C includes highly suspected BrP; however, provocative testing is not justified, such as in cases with recent surgical right ventricular outflow tract manipulation 7 or BrP secondary to inappropriate ECG high pass filters. 8 The systematic diagnostic criteria discussed needs to be applied for suspected cases of BrP.
We agree with the authors that the term ‘Brugada phenocopy’ should be used to replace ‘Brugada-like ECG pattern’ in the absence of true Brugada syndrome, in order to achieve consistency in the literature.
- © Royal College of Physicians 2015. All rights reserved.
Article Tools
Jump to section
Related Articles
Cited By...
- No citing articles found.