Types 2 and 3 Brugada have been merged into Type 2. The diagnoses have been perplexing for years because they have been based on a "saddleback" morphology. However, saddleback morphology is a very common normal variant: "saddleback" morphology is rarely Brugada pattern and even more rarely Brugada syndrome.
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This is a post showing the difficulty of the decision to place an implanted defibrillator.
A young athlete presented with syncope. Here was his ECG:
|There is an rSr' with ST elevation and postive T-wave, creating a "Saddleback" in both V1 and V2|
Brugada syndrome is a condition which can lead to polymorphic ventricular tachycardia, ventricular fibrillation, and sudden death. Identifying it before death is important.
Brugada syndrome requires BOTH 1) Brugada ECG pattern and 2) clinical criteria.
Here is an example of type I Brugada pattern during fever that disappeared after antipyresis. It can be transitory and uncovered in a variety of situations (see below).
The recognition and management of Type 1 Brugada pattern ECG is not entirely straightforward, but, in my opinion, it is far easier than the recognition and management of patients with possible Type 2/3 Brugada (Type 3 has morphology has now been incorporated into type 2). Here one of the Brugada brothers outlines the management of possible Brugada syndrome, but does not discuss type 2 in enough detail for me to understand it.
Many articles and web sites simply state that a Type 2 Brugada pattern has a "saddleback" in V2. They discuss it no further. This is not helpful, because a saddleback is a very common pattern in V2 (up to 7% in of patients with no apparent heart disease) and is a normal variant in the vast majority of cases, especially in athletes.
Saddleback is called saddleback because of an r'-wave (rSr') with an upright T-wave, forming a saddle. This is also known as right ventricular conduction delay, and, if the QRS is wide enough (but not greater than 120 ms), it is incomplete right bundle branch block (I-RBBB).
How does a non-electrophysiologist go about suspecting Type 2 Brugada?
Again, one must distinguish between the syndrome and the ECG morphology. The morphology alone is not enough for the diagnosis. There must also be the right clinical context (see below) or positive electrophysiologic testing.
How do we recognize type 2 Brugada morphology on the ECG? Fortunately, there was a consensus paper on this topic written by Bayes de Luna and the Brugada brothers. Here is the full text of it.
There is also a very nice paper (full text html link): Differential diagnosis of rSr' pattern in Leads V1-V2: Comprehensive Review and Proposed Algorithm. This is by the same authors of the new criteria for type 2 Brugada, so it is fairly authoritative. (Here is a link to the full text pfd).
Here is a differential diagnosis of rSr', modified from the rSr' paper:
A. Benign Patterns: -r' is of fast inscription, unlike in RBBB or Brugada, both of which have a wider R'. Caused by:
1. Higher placement of leads V1, V2
2. Normal variant, with late activation of the posterobasal LV
3. Incomplete RBBB, with delayed conduction through right bundle. No associated adverse outcomes. However, there is a higher incidence of subsequent development of complete RBBB.
4. Athletes: 35-50% due to physiologic RV enlargement
5. Pectus Excavatum, due to change of heart location in chest
B. Pathological Patterns: -r' often taller then -r, with slower ascent/descent
1. Type 2 Brugada pattern
2. RV enlargement, hypertrophy from a variety of pathologies
3. Arrhythmogenic RV dysplasia (ARVD)
6. Na channel blockers (anti-dysrhythmics, TCAs)
Let's go back to our case, with more detail:
A young athlete had a painful condition for which he was seen in the ED. After an episode of pain, he had a syncopal spell with complete loss of consciousness and postural tone, with spontaneous awakening. There was a prodrome which seemed vasovagal in character. He had started having lower abdominal discomfort and pressure, associated with some diaphoresis, then started feeling dizzy and passed out. He spontaneously regained consciousness. He had no prior history of syncopal spells. There was no family history of premature sudden cardiac arrest in first degree relatives. There was no history of exertional syncope or post-exertional syncope. He had a normal exam in the ED.
Here is the ECG again:
|Is it type 2 Brugada pattern?|
Is it type 2 Brugada syndrome?
The short answer is NO.
1. It is not type 1 Brugada.
2. The takeoff/downstroke of the ST segment in V1 and V2 is not flat enough ("beta" angle not wide enough) for it to be type 2 Brugada. A pronounced r'-wave is common in athletes.
Here is the long answer
Below I summarize the paper I mentioned above, entitled (with full text link): Current electrocardiographic criteria for diagnosis of Brugada pattern: a consensus report
Diagnosis of Brugada Syndrome requires both:
1. Brugada pattern ECG (either Brugada Type 1, or the newly defined Brugada Type 2)
Findings may be dynamic and are sometimes concealed; findings may be observed only in certain circumstances such as fever, intoxication, electrolyte imbalance, presence of sodium channel medications/drugs, or vagal stimulation.
2. At least one of the following:
(a) survivor of cardiac arrest,
(b) witnessed/recorded polymorphic ventricular tachycardia (VT),
(c) history of nonvagal syncope,
(d) familial antecedents of sudden death in patients younger than 45 years without acute coronary
(e) Type 1 Brugada pattern in relatives.
Type 1 Morphology
Here is Type 1 pattern in V1 and/or V2, which is quite recognizable:
|R' wave must have amplitude of at least 2 mm|
Corrado index (see below) = 1.5/0.5 = 3.0. Thus it is greater than 1.0.
1. R'-wave at least 2 mm in V1 or V2
2. But no distinct R'-wave because the ST segment takes off at an angle from the peak
3. The ST segment is convex upward ("coved"). [They use terminology of "concave downward"]
4. The peak at the high takeoff does not correspond with the J-point. It is BEFORE the J-point, as measured in other leads (such as lead II across the bottom).
5. Gradual downsloping of ST segment such that at 40 ms after the takeoff, the decrease in amplitude is less than 4 mm (in this example, it is less than 1 mm). In normal RBBB, the decrease in amplitude is much greater (see this example).
6. ST is followed by a symmetrically negative T-wave
7. "The duration of QRS is longer than in RBBB," and "there is a mismatch between V1 and V6." This criterion is perplexing and not well explained.
8. The downsloping should be such that the Corrado index is greater than 1.0 (see example above).
Corrado index is the ratio:
[ST elevation at the J-point]
[ST elevation at 80 ms after the J-point].
In athletes, the index is less than 1.0 due to a horizontal or upsloping elevated ST segment, as here:
|Corrado index less than 1 in an athlete, as ST segment slopes up|
Criteria for Type 2 Brugada:
In the consensus paper we are discussing here, types 2 and 3 Brugada have been merged into one type called type 2. They specify the criteria to be used (below).
Here is an example from the article:
a) An RSr' with a typical saddleback pattern in V1 and/or V2.
b) V1 may have either an upright, flat, or inverted T-wave (in our case above it is inverted).
c) T-wave in V2 is usually but not always positive.
d) Minimum ST segment ascent of 0.5 mm. There could be no saddle without an ascent.
Once these are fulfilled, there should be, in lead V2:
1. High take-off of the descending limb of the r' at least 2 mm above the isoelectric line (in our case, it is greater than 2 mm). The r'-wave is thus not distinct, as it is in benign causes of rSr'
2. Mismatch between QRS duration in leads V1 and V6 (longer in lead V1). This helps to distinguish from RBBB, in which the QRS duration is equal in V1 and V6.
3. As with Type 1, the peak of the r'-wave does not correspond to the J-point in other leads.
4. The base of the triangle outlined should be longer than 3.5 mm. This confirms that the slope of the ST segment is flat enough for the diagnosis. I explain this in an annotated version here:
I have done this with lead V1 of our ECG:
|The distance from the S-wave to the almost vertical line is less than 3.5 mm, so does not meet criteria.|
|This drawing is incorrect, and only to show how it should NOT be done.|
Both lines must be drawn from where the downsloping begins at the top of the r' wave.
The criteria as studied in these comparison populations were approximately 90% sensitive and 90% specific in this study.
This was recorded later:
|All the suspicious findings are gone. There is only normal variant ST elevation (early repol)|
In patients with Brugada, the Brugada morphology can be unmasked by recording V1 and V2 at higher interspaces (see this paper).
In another paper, it is shown that healthy patients may have false positive Type 2 morphology if the leads are placed too high, but NOT type 1 (full text link)! (Chung EH. Brugada-type patterns are easily observed in high precordial lead ECGs in collegiate athletes. Journal of Electrocardiology 47 (2014) 1–6.)
This was done here:
Additional etiologies were considered for his syncope given he is a collegiate athlete including HOCM, catecholaminergic polymorphic VT, and arrhythmogenic right ventricular dysplasia. Transthoracic echo did not show any evidence of HOCM or right ventricular dysplasia. EF was normal. He had no known family history of sudden cardiac death at a young age.
The electrophysiologist was confident that this was not Brugada, that a procainamide challenge test could be done but that this would normally be done only for "unexplained" syncope, not for typical vasovagal syncope. The patient was discharged with no exercise limitations. He left open the possibility of an exercise test to rule out catecholaminergic polymorphic VT (CPVT), which occurs during stress and exercise. However, without an exertional component, the probability of CPVT was very low.
In fact, this ECG is either:
1) a typical athlete's mimic of type 2 Brugada, or
2) a too-high recording, or
Here is a patient who presented with recurrent pre-syncope and palpitations.
Here is lead V2 blown up:
|The base of the triangle is about 3.5 mm, and it meets the other criteria.|
This 40-something patient presented with dizziness and chest pain. The dizziness seemed to be vertigo more than pre-syncope.
Here the lines are drawn:
|The base is greater than 3.5 mm, and other criteria for type 2 Brugada Pattern are present.|
There is Brugada Pattern, but not Brugada syndrome
Here is a comprehensive article inherited dysrhythmias: Executive summary: HRS/EHRA/APHRS expert consensus statement on the diagnosis and management of patients with inherited primary arrhythmia syndromes