Recurrent syncope and bifascicular block

You are dispatched to an “unknown medical complaint.” En route to the scene, dispatch advises you that a 66 year old male is complaining of a fall with injury, chest pain, left arm pain, and nausea.

On arrival, the patient is standing in his kitchen. He is pale and extremely diaphoretic. You direct him to a chair so you can obtain a history of the present illness.

The patient states that he “passed out” in the bathroom the night before and twice this morning. The most recent episode was in the kitchen just before the patient’s spouse contacted 9-1-1.

The patient states he has always been healthy except for a “little bit of high blood pressure”, high cholesterol, and “a right bundle branch block which is at least 20 years old.” There is no other history of syncope or falls.

The patient is alert and oriented to person, place, and time, but he admits that he is “foggy” with regard to the syncopal episodes. However, he denies hitting his head and states he has no head or neck pain.

A 2 cm horizontal laceration is noted under the patient’s chin. He doesn’t remember the last time he had a tetanus shot. He is also complaining of posterior rib pain on the right side. The pain is worse with inspiration and palpation but the chest wall is stable. He denies shortness of breath. He denies arm pain. He is not nauseated at the time of EMS evaluation.

Vital signs are assessed.

  • HR: 90
  • RR: 16
  • NIBP: 105/60
  • SpO2: 96 on RA

Breath sounds are clear bilaterally

The cardiac monitor is attached.

A 12 lead ECG is acquired.


By this time the patient “feels better.” He is no longer diaphoretic and he thinks he’ll “be okay.”

The patient is adamant that he does not want to be transported to the hospital.

Do you think he needs to go to the hospital?

What do you think is causing his syncope?

How do you explain to the patient the risk he is taking by refusing care?


The 12-lead ECG shows bifascicular block (right bundle branch block and left anterior fascicular block). In addition there is a slight first degree AV block. Some cardiologists refer to first degree AV block as “PR prolongation” because it is not a true block (the impulse reaches the ventricles in a 1:1 ratio).

Others might point to bifascicular block with first degree AV block and say that this ECG shows “trifascicular block” but that is controversial. The guidelines require alternating right and left bundle branch block, or bifascicular block with alternating left anterior and posterior fascicular block, or documented second or third degree block, in addition to bifascicular block in order to call it true “trifascicular block”.

Regardless, the presence of bifascicular block in a syncope patient is concerning because it suggests that conduction through the last remaining fascicle is precarious. There’s a good chance this patient is experiencing intermittent third degree AV block, although he could also be experiencing runs of ventricular tachycardia. Without documenting the arrhythmia we can’t say for certain but this history of present illness suggests cardiac syncope.

Here is an excerpt from Epstein A, DiMarco J, Ellenbogen K et al. ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities. Journal of the American College of Cardiology. 2008;51(21):e1-e62. doi:10.1016/j.jacc.2008.02.032. (PDF)

2.1.3. Chronic Bifascicular Block

“Syncope is common in patients with bifascicular block. Although syncope may be recurrent, it is not associated with an increased incidence of sudden death. Even though pacing relieves the neurological symptoms, it does not reduce the occurrence of sudden death. An electrophysiological study may be helpful to evaluate and direct the treatment of inducible ventricular arrhythmias that are common in patients with bifascicular block. There is convincing evidence that in the presence of permanent or transient third-degree AV block, syncope is associated with an increased incidence of sudden death regardless of the results of the electrophysiological study. Finally, if the cause of syncope in the presence of bifascicular block cannot be determined with certainty, or if treatments used (such as drugs) may exacerbate AV block, prophylactic permanent pacing is indicated, especially if syncope may have been due to transient third degree AV block.”

Class IIa

1. Permanent pacemaker implantation is reasonable for syncope not demonstrated to be due to AV block when other likely causes have been excluded, specifically ventricular tachycardia (VT). (Level of Evidence: B)”

Bifascicular block is an ECG finding that should be included along with hypertrophic cardiomyopathy (HCM), the Brugada pattern, long/short QT interval, the Wolff-Parkinson-White pattern (WPW), and arrhythmogenic right ventricular dysplasia (ARVD), and of course ischemia or arrhythmia, in the evaluation of the syncope patient.

There’s no shame in transmitting an ECG to the hospital for a physician over-read. I’ve done it several times for borderline ECGs, especially for syncope, and particularly when there is no prodrome and the history does not suggest dehydration or vasovagal syncope.

In this case the patient understood the risk of refusing care and refused transport to the hospital. He was encouraged to follow up with his physician and contact 9-1-1 again if he changed his mind.

Updated 12/08/2015

Further Reading

Bifascicular Blocks – What You Need To Know


  • SoCal Medic says:

    Tom,Naturally, any syncopal episode needs explained, and the only way of doing that is by going to the hospital and being evaluated. It is hard to tell on my screen, but there appears to be elevation in V5, V6 and possibly acute in Lead I. The right bundle branch block may be old, but the Bifascicular block may not be, which is a huge concern with his recent history. Skin signs dont lie, he needs to go, and that alone through different techniques may be enough to get him to go. Explanation of the 12 Lead may work as well, he obviously has some knowledge of his past EKG’s. With any sort of syncopal episodes, you run the risk of death. TO many things can happen in a fall, driving, whatever he may be doing, not to mention the underlying cause of why he had the episode to start with.My fear is with the elevation I am seeing on my screen, plus the complexity of the block, you have to be curious as to whether or not he is losing that last conduction route, or having it impaired.What meds is he taking? What medical history within the family exists? Any recent change in diet? Intake? Output? Weight Loss?

  • SoCal Medic says:

    OK I am stupid, I missed the long PR interval, he is in the trifascicular block, and in serious danger.

  • Tom B says:

    Christopher – This is a bifascicular block (RBBB/LAFB) with borderline 1AVB, sometimes referred to as a technical trifascicular block.Some authors do not consider a 1AVB to be a true block, and it’s impossible to know whether the delay is in the AV node or the last remaining fascicle.I’ve heard that the term “trifascicular block” out of favor. It doesn’t really matter to me either way.Regardless of what you call it, the recent history of syncope makes this ECG finding very concerning indeed! (I’m trying to sound British today).In my opinion, we have to presume that the patient is experiencing transient complete heart block (or worse).Even without this ECG finding, this patient’s recent history suggests the possibility of a Stokes-Adams attack (hat tip Dr. Matera), which means that he risks death by refusing transport to the emergency department by EMS.In this case, the risk was explained to the patient, and he signed a refusal against medical advice (but agreed to have his wife take him to the emergency department).Tom

  • SoCal Medic says:

    That would be one of those cases here that I would be on the phone to a Base Station. There is one I would call because they can get a Doc on the phone a lot faster than others, and they also happen to be one of our Cardiac Care Centeres that we would utilize. Thankfully my cell has speaker phone so that I could share the conversation. One of those documentation nightmares to say the least.

  • Terry says:

    Passes out–> falls to the floor–> converts out of a complete heart block. Who needs pacemakers?

  • Catherine M says:

    Sounds like a patient of mine who passed out, turned blue and his wife shook him until he came to. He refused to go to the hospital with me, so I told him to scoot over and hand me the remote. He looked at me like I had 27 heads and said “you really think I should go?” Long story short, he agreed to be transported. While en route he thanked me for “out-stubborning” him.

  • Dave B says:

    In addition to what was mentioned earlier, what is very concerning to me are leads V2 and V3… there is concordant ST eleavtion… in RBBB, there should be no ST elevations, but discordant ST depression. In addition, i would expect discordant positive ST and T in leads II and III, but there is what i believe looks like ST depression, which could be reciprocal to the anterior elevations. this is likely a very new finding, and is very suspicious for an anterior STEMI in the presence of RBBB.

  • Baqui says:

    Except of the  heart problem, I would reconsidered aortic dissection. Extremely diaphoretic, hypotensive , and pain decrescendo type, it  seems as aortic dissection.

  • Ken Grauer says:

    Very interesting ECG in this 66yo man with syncope X 3 and refusal to go to the ED. There are a number of areas of concern – most of which were mentioned by various responders. Two of which I don't believe ANYONE honed in on – namely lead V3 … and some q waves …

    There is sinus rhythm with bifascicular block (RBBB/LAHB). I measure the PR interval at 0.20 second. The BEST way to measure intervals (be it the PR, QRS, or QT) – is to find a complex where the interval either begins or ends on a heavy line. In lead II – the 3rd complex shows the QRS to begin just a smidgeon before a heavy line. Looking over to the left you can see that the P wave preceding this 3rd complex in lead II also begins an equal smidgeon before a heavy line – therefore the PR = 0.20 second.

    0.20 second is NOT a 1st degree AV block. In fact – given the "bell-shaped curve" of PR intervals – 0.21 second is probably normal. I usually like a PR to clearly be at least 0.22 second – and that is NOT the case in this tracing.

    Even IF the PR interval was long in this case (which it is not) – I would not call this "trifascicular block" – because you do NOT know from the surface ECG if the delay is in the AV node or in the 3rd fascicle … All that said – this does NOT matter in this case – because the clinical scenario of a 66yo man with syncope X 3 and definite bifascicular block is enough by itself to merit very careful consideration for a pacemaker … (Would be nice to know if this RBBB/LAHB was new or old).

    Other findings on this tracing include small-but-real q wavges in leads I,aVL; and in V1 (I think) and V2,V3 (for sure). This strongly suggests that this patient with this 'funny-looking' RBBB has had an anterior infarct at some point in the past … The high lateral q waves (in I,aVL) could be normal septal q waves – so those don't tell us anything. But you should NOT have a qR pattern in V2 and V3 with typical RBBB – so that IS abnormal (and to me highly suggestive of prior ant MI of uncertain age).

    As to the ST-T waves – the "easy rule" is that the ST-T way should be opposite the last QRS deflection with LBBB or RBBB in the 3 key leads (= leads I,V1,V6). This IS what we see here – so the ST segments in I,V1, and V6 are all fine. The slightly depressed ST segment in lead V2 is ok (nondefinitive) – BUT – there is subtle-but-real ST elevation in lead V3 – and this lead V3 is THE MOST CONCERNING of all of the leads. This could be an acute (or recent) anterior MI. That's the ONLY lead I see with anything definitive here that may reflect acute ongoing (or recent) infarction.

    LBBB often masks infarction. There are subtle ways (ie, Smith-Sgarbossa rules and some other hints) to identify acute MI with LBBB – but most of the time you won't see that much … In contrast – you much more often will see some clue of ongoing ischemia/infarction with RBBB. Not always (!) – but often, if you look. Lead V3 is clearly abnormal – so I'd repeat the 12-lead as soon as I could (to see if there is any evolution) – try to get an old tracing for comparison – and have high index of suspicion that this might be an acute STEMI in evolution.

    The ST coving we see elsewhere (in leads I,II,aVL,V5,V6) is really nonspecific and to my eye not indicative of any definite acute change.

    For anyone interested – plenty of download didactics and clinical examples available at this web page:

  • john shuey says:

    anyone miss the idea of a head injury?  With a cut on the chin, that spells head wound plus too much more.  Heart is one thing but a bruised brain is another.  This won't show up on a 12 but even pearl looks past surface to what is inside.  Don't chance it. Get LEO support if necessary but GO!!!!!!!!!!!!!!

  • Aaron says:

    aVR has the appearance of STE, but with the morphology I’m not 100%. However I’d still go with my gut feeling of it to be a clinical finding.

  • Mark says:

    LEO support?! On what grounds? Informed consent and refusal is just that informed. You cannot railroad somebody with threat or under duress of law enforcement. Copping a squat in their living room to emphasize your belief that they will pass out again thereby allowing transport as implied would be applied pressure. Explaining the very likely threat to life to the elderly is seldom effective as most of my patients care far more about the time away from loved ones and the shocking cost of it all. They would rather pass away at home than incur cost. Explaining how the loved one would be impacted by the process of their dying on the floor works fairly well too.
    It’s telling that calling the cops on an oriented patient making an informed decision is even an option. When a patient makes what WE think is a bad decision our obligation is to inform them better, make base,nhave them speak with a MD document and witness/sign everything. When/if they do go down we return and give them our best efforts respecting their wishes.
    I have run a few of those calls, the patient looks into my eyes to tell me they know they are dying and refuse treatment and transport. Two times we were called back to the same scene on the same shift one was to run the code and the other was to transport.

    Sent from my iPhone forgive spelling/punctuation

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