EXTRA COPY — ECG Blog #550 - Guess the Clinical Setting — EXTRA COPY

The ECG in Figure-1 was obtained from a middle-aged man who presented with CP (Chest Pain). I was asked for my thoughts on the rhythm.

QUESTIONS:

• What is the rhythm?
• How certain are you of your answer?
• What is the probable cause of this rhythm?

Figure-1: The initial ECG in today's case. (To improve visualization — I've digitized the original ECG using PMcardio).

My Approach to Today's Tracing: 

We are at a distinct disadvantage in Figure-1 for determining the rhythm. This is because we only see 9 beats, and because we lack a long lead rhythm strip. Nevertheless, a number of deductions can confidently be made.

• PEARL #1: LIfe is easier — IF we simply number the beats, as I have done in Figure-2. Doing so allows us to talk intelligently with colleagues about what is going on (as well as making it easier for us to appreciate relationships between P waves and neighboring QRS complexes).

Take Another Look in Figure-2:

• HINT:  Look first at the chest leads ...

Figure-2: I've numbered the beats in today's tracing.

==================================

What We See in Figure-2:

P waves are present in front of beats 7,8,9 (RED arrows in Figure-3):

• The P wave in front of beat #7 is clearly too short to be normally conducted to the ventricles. Thus, at least for this one beat #7 — there is AV dissociation.

Figure-3: RED arrows highlight the presence of sinus P waves.

PEARL #2: Recognizing that the PR interval in front of beat #7 is too short to be a normal sinus-conducted beat is the KEY clue to today's rhythm — as it tells us that beat #7 must be a ventricular escape beat!

• In contrast — the QRS complex in front of beats #8 and 9 is narrow, very different-looking than the QRS of beats #7,8,9 — and, the PR interval in front of beats #8 and 9 is constant and long enough to be sinus-conducted (I measure the PR interval in front of beats #7,8 to be ≥0.13-0.14 — and the PR interval might be longer if we were to see P waves in lead II).
• This tells us that beats #5 and 6 must be ventricular escape beats at the slightly accelerated rate of ~55/minute (the R-R interval between beats #5-6 and 6-7 being between 5-to-6 large boxes). 
• 
  
• PEARL #3: If we focus our attention on lead V3 — Doesn't the QRST complex of beat 7 look slightly different than the QRST of beats #5 and 6? (At least in lead V3 — the QRS and T wave of beat #7 are a little less tall than for beats #5 and 6). This tells us that beat #7 is a fusion beat, and proves that beats #5 and 6 are ventricular in origin (See ECG Blog #128 — for more on fusion beats).

PEARL #4: That beats #5 and 6 are ventricular escape beats — is supported by another look at QRST morphology of beats #1-thru-4 in the limb leads:

• Note in lead I — that the QRS complex begins with a very deep and wide Q wave! We virtually never see such a deep and wide initial negative deflection in left-sided lead I with normal sinus conduction. Thus, this initial deep and wide Q wave in lead I strongly suggests a ventricular etiology for the 4 beats in this lead.
• PEARL #5: Note the subtle-but-real negative deflection at the end of the QRS in each of the 3 inferior leads (YELLOW arrows in Figure-4 highlighting this negative deflection in lead III — but with a similar terminal negative deflection also being seen in leads II and aVF). This terminal negative notch most likely reflects retrograde conduction of the P wave from ventricular beats #1,2,3,4.
• I suspect retrograde conduction continues in the chest leads, and is seen after beats #5 and 6 — until slight acceleration of the underlying sinus P wave rhythm allows the RED arrow P waves in front of beats #8 and 9 to recapture the ventricles with sinus-conducted beats #8 and 9 (See the laddergram below in Figure-5). 

Figure-4: YELLOW arrows suggest retrograde conduction of P waves following ventricular escape beats.

Figure-5: Laddergram suggesting the mechanism of today’s rhythm.

My Impression: I suspect the rhythm in Figure-5 begins with 7 beats of AIVR (Accelerated IdioVentricular Rhythm) at ~55-60/minute — and ends with 2 sinus-capture beats ( = beats #8 and 9).

• The first 6 ventricular beats manifest retrograde P waves (dotted RED lines headed back to the atria).
• Slight acceleration of the rate of sinus impulses allows the RED arrow P waves to recapture the ventricles with beats #8 and 9.
• The overly short PR interval and intermediate shape of the QRS complex and T wave for beat #7 — suggests this is a fusion beat. Early arrival of this 1st RED arrow P wave in the ventricles prevents retrograde conduction of ventricular beat #7 — which therefore makes it possible for the 2nd RED arrow P wave to “capture” the ventricles with a sinus-conducted beat.

==================================

Putting It All Together:

• Today’s patient presented with CP.
• The underlying rhythm in the initial ECG appears to be sinus bradycardia and arrhythmia that is intermittently interrupted by AIVR at a rate of ~55-60/minute.
• 
  
• PEARL #6: The combination of AIVR in a patient who presents to the ED for CP — is commonly seen during the evolution of an acute OMI ( = Occlusion-based Myocardial Infarction). As a result — We need to go back and Take Another LOOK at the initial ECG in today's case, keeping in mind that acute ST-T wave changes of acute OMI may be difficult to recognize in association with a ventricular rhythm such as AIVR.

PEARL #7: When AIVR is seen in association with an evolving OMI (as is especially likely when the patient presents with CP, as in today's case) — it often represents a reperfusion arrhythmia (See ECG Blog #108 — for the basics regarding AIVR).

• As a result — correlating each serial ECG with the presence and severity of CP becomes especially important for understanding the sequence of events (and for determining whether the "culprit" artery is likely to be open or closed at the time a given ECG is recorded). 
• In today's case — We would want to find out IF this patient's CP had decreased (or resolved) at the time the initial ECG was recorded? If symptoms are less at the time of this initial ECG before any treatment has been administered — this suggests there has been spontaneous reperfusion of the "culprit" artery (in which case ECG signs of acute infarction may be especially subtle!).

In Figure-6 — I've reproduced today's initial ECG.

• Take another LOOK — with special attention for subtle signs of recent infarction.

Figure-6: I've reproduced today's initial ECG.

==================================

Subtle ECG Signs of Recent Infarction:

XXXXX

• ask in Hx for reduced CP? which if true would support that this AIVR is likely to be in setting of evolving OMI
• This makes assessment of today’s initial ECG (which i’ve reproduced and labeled in Fig 6 from Fig 3) esp. challenging

COPY fig of initial ECG now labeled from Fig 3 !!!!! 

Figure-7: XXX

todays rhythm  = AIVR with sinus capture - pt has CP, most like AIVR following acute OMI.

hard to interpret ventricular beat ST-T waves - but ST up in i,avl and chest leads - perhaps LAD?

==================================

The CASE Continues:

XXXXX 

Figure-8: XXX

XXXXXX 

Figure-9: XXX

XXXXXX  

XXXXXX 

==================================

Acknowledgment: My appreciation to Ali Ibrahim (from Tikrit, Iraq) for allowing me to use this case and these tracings. 

================================== 

=======================

========================

Ali ibrahim Almfriji, Interventional cardiologist Tikrit- Iraq (9/16/2026- FB Messenger!)

I need to let Ali know if I publish this! FB Messenger!

“Guess the Clinical Setting!”

 

THE CASE:

Good day dear prof. Ken. 49 male heavy smoker, no HTN, no DM, presented to my cardiac centre (tikrit.iraq) with 8 hours anterior STEMI, LAD totally occluded proximally , primary pci was done with TIMI III flow achieved, this is attached EKG 3 hours after procedure Rhythm analysis please

MY REPLY:

Hi. Interesting tracing! RED arrows are sinus P waves. We do not have a long lead rhythm strip — but the chest leads are the continuation of the limb leads (such that there are a total of 9 beats on this tracing). Beats #8 and 9 are sinus conducted! (RED arrows with a constant and normal PR interval). The PR interval before beat #7 is too short to conduct — so this is an escape beat. There are NO P waves seen before beat #7 — but the YELLOW arrows probably reflect P waves hidden within the QRS. Note that there is NO notching seen within the QRS of beat #1 ==> so the P wave is probably completely hidden within the QRS of beat #1. Putting this all together — Beats #1-thru-6 are ventricular at a rate between 55-60 ==> AIVR (Accelerated IdioVentricular Rhythm). After beat #6 — the SA node begins to wake up and it finally achieves a rate faster than the ventricular escape rate — which is why beats #8 and 9 are sinus-conducted. Beat #7 is a FUSION beat (the PR interval is too short to completely conduct). Note that the QRS is a little smaller than beats #5 and 6 which are ventricular — and a little larger than sinus-conducted beats #8 and 9. AIVR is VERY COMMON as a reperfusion arrhythmia — so that fact that this patient had acute LAD occlusion but was reperfused with PCI means that the expected situation for developing AIVR was present. IF the patient is hemodynamically stable and asymptomatic — then NO treatment is needed! This rhythm is almost always transient (lasting hours to a day or so after reperfusion). If the patient is symptomatic — giving some Atropine may help by speeding up the sinus node. Finally — the ST-T waves in some leads (like leads I and aVL) are abnormal — probably as a result from the recent MI. If you could give me a bit more follow-up on this case — I might want to use it as an ECG Blog (if I could have your permission for this?). I hope the above is helpful — 

 

ALI REPLY: 

This is second day post pci EKG and echo study.

Nice explanation, the patient really developed continuous AIVR immediately after reperfusion on cath lab table, and was stable hemodynamically.

Im pleased if this case used as ECG blog and to mention my name dr. Ali ibrahim Almfriji , Interventional cardiologist Tikrit- Iraq.

 

MY REPLY

Thanks so much for the follow-up! I do plan to write up this case. I’ll focus on the 1sttECG — but will probably also show the 2nd tracing. This 2nd ECG shows loss of R waves in the chest leads with some residual chest lead ST elevation. There is T wave inversion in the limb leads, consistent with “reperfusion T waves”. There is also low voltage (which may be a reflection of the extensive anterior infarction. It may be a little while before I publish this case — but I will let you know when I do. THANK YOU — 