ECG of the Week – 23rd September 2013 – Interpretation

By | 25 september 2013

A 73yr old female presents following an episode of syncope.
She is on no medication and has the following vitals:
BP 114/65 RR 18 Sats 97% (RA), Temp 36.3, BSL 6.5
Her ECG is below.
Check  out our original post and the excellent comments here.

Click to enlarge


  • 60


  • Regular
  • Sinus rhythm


  • LAD (-80 deg)


  • PR – Prolonged (~260ms)
  • QRS – Prolonged (140ms)
  • QT – 410ms


  • Upward slurring ST segment leads I, II, aVF, V2-6


  • RBBB Morphology
  • P wave 
    • Notched in lead II
    • Biphasic in lead V1
    • Negative portion in lead V1 ~60ms duration and 1mm deflection
  • Small U waves leads V2-4 (thanks to John Roe for pointing them out)


  • Bifasicular Block
    • RBBB
    • LAFB
  • 1st Degree AV Block

So it’s a trifasicular block ?

Well yes and no.

Many people refer to the combination of bifasicular block with a 1st or 2nd degree AV block as a ‘trifasicular block’, this term is obviously incorrect as a block of all three fasicles should result in complete heart block. 
Further to the inaccurate nature of the term the AHA 2009 Recommendations for the Standardization and Interpretation of the Electrocardiogram specifically recommended the term ‘trifasicular block’ not be used due to the variation in anatomy and pathology producing the pattern.
On this surface ECG it isn’t possible to tell whether all three fasicles are affected as the pr prolongation may be due to disease at the AV node, the left posterior fasicle, or the His bundle. 
In this case the concern is whether the patient has had transient complete heart block causing syncope, a situation associated with an increased risk of sudden death and high mortality rate.
These patients with bifasciular block, pr prolongation and a history of syncope or likely arrhythmia, should be referred to cardiology team for telemetry, review of current medications, and consideration for PPM insertion.
The AHA 2008 guidelines for PPM insertion are clear that an incidental bifasicular block with pr prolongation in the asymptomatic patient does not warrant PPM insertion (LoE: B, Class III recommendation).

Syncope Rules

I just wanted to briefly mention some of the syncope rules out there as it’s a topic that has come up in the ACEM Fellowship exam in the recent past (SAQ 2013.1 Q2 / SAQ 2008.1 Q1)

San Francisco Syncope Rule

Risk factors, any one or more places patient in ‘high risk’ group.
CHESS mnemonic.

  • C= History cardiac failure
  • H =Haematocrit <30%
  • E = Abnormal ECG
  • S = Shortness of breath
  • S = Triage Systolic BP <90 mmHg

Study outcome measure was serious outcome within 30 days, predefined as death, MI, stroke, SAH, arrhythmia, haemorrhage, or any condition causing re attendance and admission.
The initial validation study quotes sensitivity of 98% and specificity of 56% for predicting high risk group / adverse outcome, although other studies of the SFSR have shown a lower sensitivity and specificity.


Score total (1 point each for)

  • Age >65yr
  • History cardiovascular disease
  • Syncope without prodrome
  • Abnormal ECG 
    • (LAD, hypertrophy, ischaemia, conduction disturbance / blocks)

All cause 12 month mortality by score

  • 0 point = 0 %
  • 1 point = 0.8%
  • 2 points = 19.6%
  • 3 points = 34.7%
  • 4 points = 57.1%

As you can see a score of 2 or more is considered high risk.

The criticism of these rules is based on their limited sensitivity and lack of specificity

References / Further Reading

Life in the Fast Lane

  • Trifasicular Block here
  • Surawicz B, Childers R, Deal BJ, Gettes LS, Bailey JJ, Gorgels A, Hancock EW, Josephson M, Kligfield P, Kors JA, Macfarlane P, Mason JW, Mirvis DM, Okin P, Pahlm O, Rautaharju PM, van Herpen G, Wagner GS, Wellens H; American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; American College of Cardiology Foundation; Heart Rhythm Society. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part III: intraventricular conduction disturbances: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society: endorsed by the International Society for Computerized Electrocardiology. Circulation. 2009 Mar 17;119(10):e235-40. PMID: 19228822  Full text here
  • Epstein AE, Dimarco JP, Ellenbogen KA, Estes NA 3rd, Freedman RA, Gettes LS, Gillinov AM, Gregoratos G, Hammill SC, Hayes DL, Hlatky MA, Newby LK, Page RL, Schoenfeld MH, Silka MJ, Stevenson LW, Sweeney MO; American College of Cardiology; American Heart Association Task Force on Practice Guidelines; American Association for Thoracic Surgery; Society of Thoracic Surgeons. ACC/AHA/HRS 2008 Guidelines for device-based therapy of cardiac rhythm abnormalities.Heart Rhythm. 2008 Jun;5(6):e1-62.PMID: 18534360 Full text here
  • Quinn J, McDermott D, Stiell I, Kohn M, Wells G.Prospective validation of the San Francisco Syncope Rule to predict patients with serious outcomes.Ann Emerg Med 47 May 2006 (5): 448–54.PMID 16631985 Full text here
  • Colivicchi F, Ammirati F, Melina D, Guido V, Imperoli G, Santini M; OESIL (Osservatorio Epidemiologico sulla Sincope nel Lazio) Study Investigators.Development and prospective validation of a risk stratification system for patients with syncope in the emergency department: the OESIL risk score. Eur Heart J. 2003 May;24(9):811-9.PMID: 12727148  Full text here


  • Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.

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