Friday, October 28, 2022

I'm so sorry when medics get abused for activating the cath lab

Cortland Ashbrook from Spokane County, Washington, sent this message:

Hey doctor Smith, I wondered if you’d give me your opinion on these ECG tracings I took as a paramedic in the field?


The call was an elderly gentleman who was at home when he experienced a sudden onset of vague chest discomfort along with nausea, and left arm aching. It started while walking, and began to decrease at rest but never fully resolved. It was central and constant. He has a pacemaker for an unknown arrhythmia reason, and has a hx of a PE but is not anti-coagulated currently. I believed this met modified Sgarbossa in II, III and aVF with excessive discordance as well as reciprocal in aVL.

Initial presentation was oddly benign. He had a gradual onset of nausea, left elbow aching and a vague indescribable feeling in his chest. The nausea and elbow aching resolved with rest, and he stated the “off feeling “ in his chest was a 0-1 during transport, and even at onset was no more than a 2/10. No diaphoresis at any point, and he appeared in no distress. Both the patient and his wife attributed it to spicy food a couple hours prior, and I had to talk him in to being transported.

The ER physician was pretty rudeto me for calling an activation, but wouldn’t educate me on what I may have been misinterpreting. I’m an avid reader of your blog, and wanted your valued opinion on this.

Here are the ECGs:

Here I use the PMCardio app (from Powerful Medical) to clean and digitize the image:
There is a paced rhythm, with wide QRS.
In inferior leads, the QRS is so distorted by the massive ST Elevation that it is even hard to distinguish from the ST-T!
Lead II has massive excessively discordant STE and III and aVF have massively concordant STE.
Leads V5 and V6 have huge proportionally excessively discordant STE.

This is obviously diagnostic of inferior and lateral Occlusion Myocardial Infarction.
The location of the infarct is clear, but that does not necessarily tell you what artery it is.

Learn about the Smith-Modified Sgarbossa Criteria for Diagnosis of OMI Paced Rhythm:

Dodd, Meyers, Smith, et al.  Annals of Emergency Medicine 2021.  Electrocardiographic diagnosis of acute coronary Occlusion Myocardial Infarction in ventricular paced rhythm using the modified Sgarbossa criteria.

Cortland recorded another ECG:

Again, the PM Cardio App is used to improve the image:
There is again obvious OMI, with hugely excessively discordant STE in lateral leads and of course also in inferior leads (with excessively discordant reciprocal ST depression in aVL).

Diagnosis: Obvious Inferior and lateral Occlusion MI.

Smith Response: Cortland, you were absolutely right. There is no doubt about these 2 EKGs: they are due to acute coronary occlusion. These are not even CLOSE to being subtle!! Unfortunately, many or most physicians, including EM and cardiology, do not know this and too many also are too arrogant to learn from a paramedic. Great job!! You should get followup on the case.

Cortland: Thank you so much for your reply! I just got the follow up that he had a near complete very proximal LAD occlusion, and a complete PDA occlusion. He went into cardiogenic shock and is intubated in the cardiac ICU. Not the culprit artery I was expecting but potentially a wraparound LAD?

Smith: You should try to educate him/her

Cortland: I tried to mention the findings and the sensitivity of modified Sgarbossa but he brushed me off. I really appreciate you getting back to me!

MY Comment by KEN GRAUER, MD (10/23/2020):
Today's tracing is similar to many others that we've published on Dr. Smith's ECG Blog — namely, an EMS pacer tracing obtained in the field from an elderly patient with new chest pain — which despite concern by medics in the field, was discounted by the physician charged with initial care of the patient. 
  • For clarity — I've chosen the 2nd tracing in today's case to comment on, since it had less artifact. To improve visualization — I've digitized the original ECG using PMcardio (Figure-1).

My approach to this case was similar to that described in My Comment — at the bottom of the page in the October 3, 2018 post in Dr. Smith's ECG Blog:
  • Even before looking at the ECG — today's patient is in a "high prevalence" population for acute coronary disease because he is elderly, obviously has underlying heart disease (after all, he has a permanent pacer) — and he was bothered by new-onset chest pain severe enough that he summoned the EMS team to his home.
  • Modified-Smith-Sgarbossa Criteria provide objective criteria for assessing patients with LBBB and/or pacemaker tracings for acute coronary disease. That said — I favor beginning with a qualitative approach, which has served me well over a period of decades. Doing so — my immediate conclusion was identical to that of Dr. Smith — namely, that there is no doubt that today's ECG indicates acute coronary occlusion until proven otherwise.

Figure-1: The 2nd ECG in today's case. (To improve visualization — I've digitized the original ECG using PMcardio).

Abnormal Findings in ECG #2:
The rhythm in ECG #2 is challenging to assess — because the QRS is wide and slightly irregular — there are no discernable P waves — and there is much artifact. Despite the absence of pacer spikes — this presumably is a paced rhythm.
  • The main premise of my qualitative approach — is to be suspicious of an acute cardiac event when you see ST-T wave findings that shouldn't be there. Admittedly — this may be challenging to assess with pacer tracings because of the many variations in QRS morphology that may be seen given different types and different placements of the various cardiac pacemakers. Despite this — it will sometimes be quite obvious (as in today's case) that the ST-T wave deviations seen in a number of leads just should not be there.

  • I've drawn horizontal dotted-RED lines in multiple leads to clarify the ST segment baseline. RED arrows in these leads point to the change in angulation of the ST segment, which indicates the amount of ST elevation in these leads. The amount of ST elevation in multiple leads is clearly excessive, given relative size of the QRS complex in these leads. In addition — ST-T waves are clearly hyperacute (ie, hypervoluminous) in many leads with respect to proportionality with QRS amplitude.

  • NOTE: The size of QRS amplitudes is limited in many prehospital ECG recorders. For example — the reason for the horizontal ending to the QRS at its lowest point in leads V2, V4 and V5 (horizontal dotted BLUE lines in these leads) — is that S wave depth was limited to 10 mm. This makes it difficult to apply the rule of "proportionality" in these leads (because we don't know how deep the S waves really are). But QRS amplitude was not limited in the limb leads or in lead V6 — and there should be no doubt about the acuity of ST segment deviations in these leads!

BOTTOM Line: Despite the fact that ECG #2 is a paced tracing — the diagnosis of acute OMI is not in doubt. 

No comments:

Post a Comment

DEAR READER: I have loved receiving your comments, but I am no longer able to moderate them. Since the vast majority are SPAM, I need to moderate them all. Therefore, comments will rarely be published any more. So Sorry.

Recommended Resources