Can you see through this wide complex rhythm?

Written by Pendell Meyers

A 76 year old man with history of CHF, moderate aortic stenosis, insulin-dependent diabetes, hypertension, stroke, CAD s/p stents, CKD, PVD, OSA presented to the ED with shortness of breath and chest pain off and on for 2 weeks. This afternoon his symptoms intensified so he called EMS.

In the ED he appeared acutely ill, with HR 100-115, RR 20-25, BP 93/52, hypoxic to 88-92% on 5L nasal cannula, afebrile.

Here is his presentation ECG, followed by his baseline ECG on file:

Presentation ECG.

Baseline ECG.

The presentation ECG shows ventricular paced rhythm at rate of approximately 120 bpm. The J-point in V3 is inappropriately isoelectric, and there is excessively discordant STD in V4-V6 and I. There is excessively discordant STE in aVR. These findings suggest diffuse severe supply-demand mismatch (a.k.a. diffuse subendocardial ischemia).

Back to the case:

The clinicians suspected cardiogenic shock and initiated resuscitation. He was also found to be in diabetic ketoacidosis. He was admitted to the CCU, and the cardiologists were worried that they were missing ECG findings because of the paced rhythm, so they decided to temporarily turn off the pacemaker to capture an ECG in normal rhythm.

Here are his two ECGs from that time, the first before suspending his pacemaker and the second after:

With pacing

Paced rhythm with the same findings as the presentation ECG.

Pacing suspended

Atrial fibrillation with narrow QRS. Large STD in V3-V6, I, II, III, and aVF, as well as STE in aVR and V1.

Because of these findings in normal QRS rhythm, he was then taken for urgent cath. He was found to have severe three vessel disease, with a proximal LCX lesion that was 95% stenosed with TIMI 3 flow at the time of cath. A stent was placed in the LCX, and an impella pump was placed for persistent cardiogenic shock.

Over the next 24 hours the ECG normalized:

The patient survived despite a complicated hospital course.

Commentary:

Just like Occlusion MI can be seen "through" left bundle and ventricular paced rhythms, so can other ECG findings such as those of diffuse subendocardial ischemia.

In our validation study of the modified Sgarbossa criteria, we performed an exploratory analysis for this very question. Here are a few relevant quotes from the study:

"We identified 4 patients who did not meet our definition of ACO, yet did have

notable catheterization findings and outcomes warranting immediate diagnosis.

These 4 patients were found to have AMI and new 3-vessel or left main coronary

artery disease with either an acute but non-occlusive culprit lesion or very high

troponin. Peak 24-hour troponin T levels were 0.25, 0.75, 1.04, and 6.61 ng/mL.

Two of these 4 required urgent or emergent CABG. We categorized these patients as

having “acute 3-vessel/left main disease myocardial infarction” (3V/LMD). Three of

these four patients had discordant ST elevation (STE/S ratio ≤-0.20 in lead aVR), but

only one of these three was positive by the -0.25 modified criteria. Two of the four

3V/LMD patients also met the overall discordance criteria (≤-0.30) due to

widespread ST depression (ST depression/R-wave ratio ≤-0.3) in various other

leads, including III, aVF, V5, and V6. None of the four met the weighted or

unweighted original Sgarbossa criteria."

"Our exploratory analysis of the four patients in our study with acute myocardial

infarction due to severe 3-vessel or left main disease (but without proven

ACO) suggests that this condition may also be identifiable in the context of LBBB. We

believe these patients’ ECGs may not be as reliably identified by the criteria

designed to detect ACO, mainly because they did not manifest concordant ST

elevation. In the same way that acute 3V/LMD presents in normal conduction as

diffuse ST depression with reciprocal ST elevation in aVR, we found that it usually

presented in LBBB with excessively discordant ST depression in V5 or V6 with

excessively discordant ST elevation in aVR (see Figures 7 and 9 in the online

appendix)."

Here are figures 7 and 9 from the online appendix:

 Figure 7: This ECG was recorded in a patient who was found to have a non-occlusive LAD culprit lesion in the setting of severe 3-vessel disease. Notice the extremely proportionally excessive discordant ST depression in leads V5 and V6, with proportionally excessive reciprocal ST elevation in lead aVR.

Figure 9: In this ECG the conduction pattern alternates between normal and LBBB, showing the equivalent findings of severe global ischemia (in this case due to severe 3-vessel disease with critical left main stenosis requiring emergent CABG) in both conduction patterns. The predominant findings are diffuse ST depression with reciprocal ST elevation in aVR, which manifest in LBBB as proportionally excessive discordant ST changes (with no concordant ST-elevation).

Learning Points:

Severe diffuse supply/demand mismatch ischemia (diffuse subendocardial ischemia) may be identified in the setting of LBBB and paced rhythms by identifying excessively discordant diffuse STD in multiple leads with STE in aVR, just as in normal QRS rhythm.

If you have the training and capability to change pacemaker settings, it may uncover ECG findings that you would not otherwise have noticed in paced rhythm. Otherwise, you should train with cases like this to be able to see "through" the wide complex rhythm.

Found comatose with prehospital ECG showing "bigeminal PVCs" and "Tachycardia at a rate of 156"

This patient with a history diabetes was found with a GCS of 4.

Prehospital EKG and strips (not shown) had "heart rate 156" (according to the computer interpretation) and "Bigeminal PVCs"

The prehospital 12-lead looked just like the first ED ECG:

What do you think?

Answer: The "bigeminal PVCs" is really a QRS followed by a very narrow peaked T-wave, which was so narrow that it was mistaken for a separate QRS.  The heart rate is 78, not 156.  Notice also the very long ST segment, most easily seen in inferior leads.

This ECG is pathognomonic for severe hyperK, and the long ST segment is all but pathognomonic for hypocalcemia. So I knew immediately that the patient needed a lot of IV calcium, and, based on the prehospital ECG, we gave 6 grams of calcium gluconate before even drawing blood for lab values.

When we did get a chem back (drawn after 6 g Ca gluconate), the K was 9.0 mEq/L and the ionized calcium was not reported because it was too low.

The patient had a glucose of 1400, was severely dehydrated, and after receiving 4 liters of fluid, albuterol, and insulin, the K had dropped precipitously to 5.8 and the ECG improved:

The Calcium AFTER 6 g of treatment was 8.2 mg/dL.

Cr was 8.0 (previous was normal).  The patient had hyperK due to acute renal failure.

Learning Points:

1. Learn all the different pathognomonic ECGs of severe, life threatening hyperK.
2. A long ST segment is typical of hypocalcemia
3. Immediate treatment of HyperK is calcium. It is safe even when there is no hypocalcemia, but is particularly safe if there is hypocalcemia, which you can infer from a long ST segment.

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Comment by KEN GRAUER, MD (12/11/2018):

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I love this case — because it brings home 3 of my favorite teaching points about electrolyte disorders and ECG interpretation. For illustrative purposes — I’ve put both tracings in this case together in Figure-1.

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Figure-1: The 2 ECGs in this case (See text). 

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Teaching Point #1: You can sometimes make the diagnosis of acute DKA (Diabetic KetoAcidosis) from an ECG, even before blood values come back! If the clinical setting is “right” (ie, an acutely ill patient with a history of diabetes, or impaired mentation with Kussmaul respiration) — and, the initial ECG suggests marked hyperkalemia — then acute DKA should be immediately considered.There just aren’t that many clinical conditions that cause hyperkalemia. Among the most common entities are:

• Renal failure (acute or chronic).
• Severe acidosis.
• Use of K+-retaining medications or K+ supplementation (especially if the patient has underlying renal impairment).
• Severe dehydration.
• Addison’s disease (adrenal insufficiency) — which is not common ...
• Destruction of red blood cells due to trauma, severe injury or burns.

COMMENT — An ECG can often be obtained in the ED before lab values come back. If the tracing suggests significant hyperkalemia — then think of the above entities as you correlate clinically to the patient in front of you in your search for a cause. Considering that acute DKA often presents with 3 of the above causes of hyperkalemia (ie, severe acidosis, renal impairment, and dehydration) — acute DKA should be high on your list unless another etiology is obvious.

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Teaching Point #2: The typical ECG picture of hypocalcemia is a long, relatively normal (and typically isoelectric) ST segment — at the end of which is a relatively normal T wave (unless the T wave is altered by another disorder, such as hyperkalemia).

• Although the ST segment manifests abnormal coving in multiple leads in ECG #1 (Figure-1) — ST segments are strikingly prolonged without obvious elevation or depression — and only then … comes the T wave. As per Dr. Smith, the pointedness and narrow base of T waves in virtually every lead in ECG #1 is the result of hyperkalemia.

COMMENT — Hyperkalemia and hypocalcemia often occur together in renal failure. This makes it easier to suspect associated hypocalcemia when a hyperkalemic-looking ECG shows an unexpectedly prolonged ST segment prior to the peaked T waves.

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Teaching Point #3: There is a REASON why the initial ECG ( = ECG #1 in Figure-1) in this case looks highly unusual! By this I mean that although T waves are clearly pointed and peaked with a narrow base — we don’t usually see biphasic T waves in hyperkalemia, as are present in leads V1-thru-V6!

QUESTION: Why do the T waves in ECG #1 look so strange that they were mistaken for PVCs?

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ANSWER: The effect of hyperkalemia on the ECG is additive to (superimposed on) however the baseline ECG looked! This fundamental point is all-too-often ignored!

• IF the baseline ECG is relatively normal — then development of severe hyperkalemia will produce a picture of tall, peaked and pointed T waves with a narrow base — ultimately resulting in loss of P wave amplitude, bradyarrhythmias, and QRS widening.
• BUT — IF the baseline ECG is abnormal, with preexisting ST-T wave depression — then the degree of T wave peaking from hyperkalemia may be significantly attenuated.
• FINALLY — IF the patient presenting with hyperkalemia is also acutely ischemic — these ischemic ECG changes may not be recognizable until serum K+ is normalized and the ECG is repeated.

COMMENT — The ECG after treatment in this case is the bottom tracing in Figure-1 ( = ECG #2). It should be emphasized that serum K+ was not yet normal at the time ECG #2 was recorded (serum K+ = 5.8 mEq/L) — so we are not privilege to a true “baseline” tracing for this patient. That said, it is clear that fairly deep, symmetric T wave inversion is present in leads V3, V4 and V5 of ECG #2 — with at least suggestion of abnormal ST segment coving in these leads. Whether these ST-T wave abnormalities in ECG #2 are new (and whether they might be even more pronounced if the ECG was repeated after complete resolution of electrolyte disorders) is uncertain. BOTTOM LINE: Seeing ECG #2 explains the highly unusual picture of ST segment coving with biphasic T waves that was seen in the initial ECG ( = ECG #1) when serum K+ = 9.0 mEq/L.

• P.S. — Did you notice that the QRS complex in ECG #1 is wide? (ie, it appears to be at least 0.12 second in duration in leads V2,V3,V4). That this QRS widening in ECG #1 is real, and is the result of marked hyperkalemia is verified by the presence of a decidedly more narrow QRS complex in ECG #2 after treatment.
• P.P.S. — Did you notice that in addition to QRS widening — there is also a marked axis shift between the initial ECG ( = ECG #1) and the post-treatment tracing ( = ECG #2). Given the adverse effect hyperkalemia has on conduction — the presence of an unusual frontal plane axis and/or marked axis shift from the patient's baseline tracing are additional indicators from the ECG suggesting the degree of hyperkalemia is severe!

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Final NOTE: Did you recognize that the rhythm in ECG #2 is not simply sinus? If not — then you weren’t systematic in your interpretation.

• PEARL — The easiest way to never overlook a non-sinus rhythm — is to always begin your interpretation of any ECG by spending a quick 2-3 seconds surveying every beat in the long lead II rhythm strip. If you do not see an upright P wave with fixed PR interval preceding each QRS complex — then the rhythm is not strictly sinus. The only 2 exceptions to this rule are lead misplacement and dextrocardia.

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QUESTION: What then is the rhythm in ECG #2 of Figure-1?

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ANSWER: The rhythm in ECG #2 is complex. The important point — is to recognize that because the initial beats in the long lead II rhythm strip are not preceded by an upright P wave (BLUE arrows in Figure-2) — this can’t be a sinus rhythm (assuming no dextrocardia or lead misplacement).

• Admittedly, assessment of the rhythm in ECG #2 is complicated by baseline artifact and the low amplitude of atrial activity. That said — there should be NO doubt that the P wave preceding the first 9 beats is negative in lead II (BLUE arrows), as well as in the other inferior leads. A small upright P wave does appear to be present in front of the QRS in lead I. This suggest this is a coronary sinus rhythm.
• Beat #10 is early. It is a PAC.
• Sinus rhythm clearly resumes for the last 4 beats on this tracing (ie, beats #13-16) — as each of these beats is preceded by a small-but-clearly-upright P wave with a fixed and normal PR interval (RED arrows).
• Sinus P waves also appear to precede beats #11 and 12 (RED arrows) — but the PR interval preceding these 2 beats is short, suggesting they are junctional escape beats.

Figure-2: We have labeled ECG #2 to explain the rhythm (See text).

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Clinically — Brief appearance of a coronary sinus rhythm until a PAC reset the sinus pacemaker did not affect outcome in this case. My purpose in discussing the rhythm in ECG #2 was simply to highlight how easy it is to overlook subtle arrhythmias if one is not meticulous and systematic. Failure to do so may affect clinical outcome in other cases ...

Two cases of ST Elevation with Terminal T-wave Inversion - do either, neither, or both need reperfusion?

Written by Pendell Meyers with edits by Steve Smith

I was sent these 2 ECGs with no clinical information other than chest pain:

Do either or both of these ECGs show ischemic changes? If so, what should you do and why?

Let's take them one at a time.

What would your response be?

I responded: "Awesome classic benign T wave inversion! That's the patient's baseline normal variant. ... But if it were a good story with exertional syncope or something you'd have to treat it like it could be HOCM, etc. Tell me more."

There is sinus rhythm with very large voltage and associated repolarization abnormalities. In V3-V6 there are classic and dramatic findings of BTWI including small or no S-waves, large R-waves, pronounced J-waves, ST-elevation, and steep dramatic T-wave inversions, all with a short QT interval.

Later, I was told this history:

The patient was a 17 year old African American male with history of asthma who presented with chest tightness and shortness of breath for 6 hours. He improved almost completely after a duoneb (albuterol and ipratropium). However the clinicians were surprised by his unusual ECG findings. 

He had no prior ECG on file. He had no family history of cardiac issues or sudden death. Labs were normal, including troponin x2. He is able to play basketball routinely without any issues.

In the ED he had a CT angio which was negative for aortic dissection. He was admitted for observation and cardiology consult. He had a normal CT coronary angiogram, as well as a normal cardiac echo. Serial troponins were negative.

Smith Comment: Although this ECG pattern is not ischemic, it may sometimes be seen in individuals with hypertrophic cardiomyopathy. For this reason it may be prudent to obtain an echocardiogram in these patients before they are allowed to engage in vigorous athletic activity. [1,2]

Let's return to the other case:

There is sinus rhythm with QS-waves in V1-V3. There is ST elevation in V1-V3 as well, with convex appearance and some terminal T-wave inversion. 

I advised the team that the patient has had a large anterior MI, but I cannot tell how long ago it occurred. It could be 6-12 hours after completion or reperfusion of anterior MI, or it could be days to years after the event. I advised them that I do not see any signs of reocclusion on this ECG, meaning that I do not think this ECG at this time represents acute LAD occlusion that would benefit from emergent reperfusion.

Let's use the LV aneurysm rule on this ECG to see if it supports our theory:

Here is the rule, which should be used if there is suspicion of aneurysm (there are Q-waves in V1-V4, especially QS waves): "If there is one lead of V1-V4 with a T/QRS ratio greater than 0.36, then it is acute MI. If less than 0.36, it is either subacute (over 6 hours) or old." [3,4]

V1 = 2/10 = 0.20

V2 = 2/12 = 0.17

V3 = 1.5/7 = 0.21

So it agrees with our visual subjective interpretation that this is either subacute or old.

I later found out that the patient had history of an LAD occlusion MI two months ago, with a stent placed.

He was taken for emergent cath due to his history and the ECG findings including ST elevation (although ST elevation is a terrible way to distinguish ischemia from non-ischemia). 

His cath showed perfectly patent stents.

Three serial troponins were undetectable.

His serial ECGs did not change.

He was discharged home.

Learning Points:

There are many causes of ST elevation, terminal T-wave inversions, and both simultaneously. Experience with the cases on this blog can teach you how to differentiate them.

Wellens syndrome (or reperfusion in general) is an important cause of terminal T-wave inversions. See these cases below for examples. However, Wellens' syndrome includes resolution of chest pain and preservation of R-waves, in addition to T-wave inversion. Thus, this second case would not be an example of Wellens' syndrome.

Classic Evolution of Wellens' T-waves over 26 hours

2 Cases of Resolved Chest Pain with Dynamic Terminal T-wave Inversion

Subtle Dynamic T-waves, Followed by LAD Occlusion and Arrest

Pseudonormalization of Wellens' Waves

More cases

Also see below for more cases of LV aneurysm morphology:

Tachycardia and ST Elevation.

Subtle Anterior STEMI Superimposed on Anterior LV Aneurysm Morphology

Is this acute STEMI? LV Aneurysm? Would you give Thrombolytics?

ST elevation and QS-waves. ECG is equivocal. Use ED Echo!!

References:

T/QRS ratio to differentiate anterior STEMI from anterior LV aneurysm:

1. Papadakis M, Carre F, Kervio G, et al. The prevalence, distribution, and clinical outcomes of electrocardiographic repolarization patterns in male athletes of African/Afro-Caribbean origin. Eur Heart J. 2011;32(18):2304-2313. doi:10.1093/eurheartj/ehr140

2. Wells S, Rowin EJ, Bhatt V, Maron MS, Maron BJ. Association Between Race and Clinical Profile of Patients Referred for Hypertrophic Cardiomyopathy. Circulation. 2018;137(18):1973-1975.

3. Validation (Klein, Shroff, Smith): Electrocardiographic criteria to differentiate acute anterior ST-elevation myocardial infarction from left ventricular aneurysm

4. Derivation (Smith): T/QRS ratio best distinguishes ventricular aneurysm from anterior myocardial infarction

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Comment by KEN GRAUER, MD (12/5/2018):

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It’s always great practice to be given tracings and “Put to the Test” as to whether you think acute changes are, or are not present. I came to the identical conclusion as did Drs. Smith & Meyers about the 2 ECGs in this case — albeit via a slightly different intuitive pathway. For clarity — I repeat the tracings in Figure-1.

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Figure-1: Two ECGs we are asked to assess, but without benefit of any history (See text).

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ECG #1:

• Knowing some History is KEY. As per Dr. Meyers — If the history of this patient was worrisome, then the onus of “proof” still rests upon us to prove there are no acute ECG changes, rather than the other way around. REMEMBER — Patients with early repolarization on their baseline ECG may develop superimposed changes of acute STEMI, that can at times be difficult to discern because of pronounced baseline benign ST-T wave repolarization changes.
• That said, in addition to the benign-appearing findings described in detail by Drs. Meyers & Smith — I thought these findings in ECG #1 were probably not acute because: i) The Q waves in the inferolateral leads are very small (these look like normal septal q waves in a patient like this with an inferior frontal plane axis); ii) There is no reciprocal ST depression; iii) Except for lead V3 — the leads with the deepest T inversion manifest the tallest R waves; and, iv) Lead V3 is perfectly consistent with being a “transition lead” (ie, V3 looks precisely as I’d expect for a lead located in between the upright T wave and predominantly negative QRS seen in V2 — and — the huge R wave with deep T inversion in V4).
• The ECG appearance of patients with hypertrophic cardiomyopathy (HCM) is highly variable. Among potential ECG findings in such patients are LBBB, RBBB, IVCD, large Q waves in multiple leads (especially in lateral and/or inferior leads); prominent septal forces (ie, relatively tall R waves in anterior leads) — and/or marked increase in QRS amplitude in various leads with notable ST-T wave abnormalities (as are seen here in ECG #1). And sometimes, the ECG of patients with hypertrophic cardiomyopathy is surprisingly unremarkable. TAKE-HOME Point: The prominent QRS voltage and marked ST-T wave abnormalities in ECG #1 should clearly prompt consideration of possible HCM. An Echo is indicated if there is any concern.

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ECG #2:

• Knowing some History is KEY. As per Dr. Meyers — the correct clinical interpretation of ECG #2 is, “Anterior MI of uncertain age, possibly recent” — with need for clinical correlation.
• Reasons we KNOW there has been prior anterior MI in ECG #2 include the following — i) There is a fragmented initial Q wave deflection in lead V3 (and when you see this initial fragmented qrS deflection — it is highly suggestive of true prior infarction); ii) There is loss of r wave (a tiny r looks to be present in V1 — but it is wiped out by the q wave in V3); iii) The q wave in V4 shouldn’t be there (because this q in V4 is larger than the tiny q in V5 — and it looks like there is no q in V6); and, iv) ST coving and T inversion is most prominent in the anterior leads that manifest abnormal initial (q wave) deflections.
• Reasons for suspecting that even if ECG changes in ECG #2 were to be recent — they probably do not reflect acute coronary occlusion, include the following — i) It usually takes a little time to develop the fragmentation and the amount of lost anterior forces as is seen in leads V1, V2 and V3 of ECG #2; and, ii) The amount of ST elevation in the anterior leads is modest compared to significant loss of anterior forces and the extent of T wave inversion. NOTE: Exceptions always exist, and it is possible to develop the ECG picture seen in ECG #2 over a fairly short period of time … — BUT — “the look” of this tracing is such that I thought the changes in ECG #2 were probably not acute.