Brugada phenocopy: A new electrocardiogram phenomenon

Abstract

Brugada phenocopies (BrP) are clinical entities that are etiologically distinct from true congenital Brugada syndrome. BrP are characterized by type 1 or type 2 Brugada electrocardiogram (ECG) patterns in precordial leads V1-V3. However, BrP are elicited by various underlying clinical conditions such as myocardial ischemia, pulmonary embolism, electrolyte abnormalities, or poor ECG filters. Upon resolution of the inciting underlying pathological condition, the BrP ECG subsequently normalizes. To date, reports have documented BrP in the context of singular clinical events. More recently, recurrent BrP has been demonstrated in the context of recurrent hypokalemia. This demonstrates clinical reproducibility, thereby advancing the concept of this new ECG phenomenon. The key to further understanding the pathophysiological mechanisms behind BrP requires experimental model validation in which these phenomena are reproduced under strictly controlled environmental conditions. The development of these validation models will help us determine whether BrP are transient alterations of sodium channels that are not reproducible with a sodium channel provocative test or alternatively, a malfunction of other ion channels. In this editorial, we discuss the conceptual emergence of BrP as a new ECG phenomenon, review the progress made to date and identify opportunities for further investigation. In addition, we also encourage investigators that are currently reporting on these cases to use the term BrP in order to facilitate literature searches and to help establish this emerging concept.

Keywords: Brugada phenocopy; Brugada syndrome; Cardiomyopathy; Electrocardiogram filters; Electrolytes; Myocardial ischemia; Pulmonary embolism.

Figure 1

Type 1 Brugada phenocopies. A: True congenital type 1 Brugada electrocardiogram (ECG) pattern; B: Type 1 Brugada phenocopies (BrP) in a patient with an acute inferior ST-segment elevation myocardial infarction with right ventricular involvement; C: Type 1 BrP in a patient with concurrent hyperkalemia, hyponatremia and acidosis; D: Type 1 BrP in a patient with an acute pulmonary embolism; E: Type 1 BrP in a patient with hypokalemia in the context of congenital hypokalemic periodic paralysis.

Figure 2

Type 2 Brugada phenocopies. A: True congenital type 2 Brugada electrocardiogram (ECG) pattern; B: Type 2 Brugada phenocopies (BrP) in a patient with an accidental electrocution injury; C: Type 2 BrP in a patient with congenital pectus excavatum causing mechanical mediastinal compression; D: Type 2 BrP as a result of an inappropriate high pass ECG filter.

Figure 3

Brugada phenocopy clinical reproducibility. A: Electrocardiogram (ECG) on presentation while the patient is hypokalemic consistent with a type 1 Brugada ECG pattern; B: After correction of the electrolyte abnormality, the ECG normalizes; C: While in hospital, the patient again becomes hypokalemic with recurrence of the type 1 Brugada ECG pattern; D: Subsequent normalization of the ECG pattern after potassium is corrected.