See what happens when a left main thrombus evolves from subtotal occlusion to total occlusion.

Written by Magnus Nossen

The patient in today's case is a male in his 70s with hypertension and type II diabetes mellitus. His wife contacted the ambulance service after the patient experienced an episode of loss of consciousness. The syncope lasted about 2-3 minutes according to his wife. He woke up alert and with chest pain which he also had experienced intermittently over the previous few days. The ECG below was recorded about 20 minutes after he regained consciousness. What do you think?

ECG #1

The above ECG shows sinus rhythm at about 60 bpm. There is RBBB and LAHB. The PR interval is normal. The first task when assessing a wide complex QRS for ischemia is to identify the end of the QRS. When you have identified the end of the QRS complex and the beginning of the ST segment you can assess whether there is concordant ST segment elevation, concordant ST depression or whether there are excessively discordant ST segments. Below (Figure A) I have marked the end of the QRS complexes by drawing a vertical line through the J-point of the standard and precordial leads. Blue arrows indicate ST depression and the red arrow ST elevation.

Figure A

It now becomes apparent that there is ST segment depression in almost every lead of the ECG (V1-V6, I, II, aVL and aVF). The ST segment in lead III is close to isoelectric, with perhaps slight ST elevation. There is ST elevation in lead aVR as expected with these widespread ST depressions. The ST segment depression in the precordial leads is excessively discordant. In leads I, II and  aVF there is concordant STD. 

This ECG has widespread ST depression and an almost "Aslanger-like" appearance. The ST segment changes are compatible with severe subendocardial ischemia which can be caused by type I MI from ACS or potentially from type II MI (non-obstructive coronary artery disease with supply/demand mismatch). 

There are multiple possible clinical situations that could account for diffuse subendocardial ischemia that is not due to ACS and plaque rupture. The history in today's case with sudden loss of consciousness followed by chest pain is very suggestive of ACS and type I ischemia as the cause of the ECG changes. In my experience, patients having a type II MI (unless caused by a tachydysrhythmia) usually have a more gradual onset of symptoms reflecting the more gradual onset of most common clinical entities associated with type II MI (e.g sepsis, anemia, hypoxemia, severe hypotension etc., etc.)

The patient was given aspirin and heparin. While preparing for transport the patient became ashen and confused with cool and clammy skin and a very weak pulse. A repeat ECG was recorded about 15 minutes after the initial ECG. What do you think has happened and what is the most likely diagnosis?

Smith: after publication, Pierre Taboulet, who has an amazing French language ECG site, notified that he sees high grade AV block in this ECG:

Arrows point to P-waves

ECG #2

Again there is a wide complex QRS due to RBBB and LAFB. The rhythm now is atrial fibrillation. In the initial ECG (ECG# 1) aVR had ST elevation. Now this lead shows STD depression. Many of the leads that showed ST depression in the initial ECG now show ST elevation! There now is marked ST elevation in leads I, aVL and V2-V6.

In Figure B below I have again marked the J point by vertical lines. The red arrows point to ST segment elevation.

Figure B

At this point, with the ECG changing from diffuse ST depression to widespread ST elevation and the patient presenting in cardiogenic shock, left main coronary artery (LMCA) occlusion is the likely diagnosis. 

There is «shark-fin-like» ST elevation in many leads. This is an ominous sign. The patient was rushed to the nearest emergency department (non-PCI facility) for stabilization. Just prior to arrival he fell out of consciousness with the below ECG on the monitor.

ECG #3

The above ECG  shows a polymorphic VT at a rate of about 180 BPM. The arrhythmia spontaneously converted before defibrillation was achieved. 

On arrival in the emergency department, invasive blood pressure was 35/15mmHg and the patient was in profound cardiogenic shock with severe confusion secondary to brain hypoperfusion. The arterial blood gas showed a lactic acidosis with a lactate level of 17mmol/L. This patient is actively dying from a left main coronary artery OMI and cardiac arrest from VT/VF or PEA is imminent! Unless some LMCA flow is restored he will not survive. You have but one option in this situation as the PCI center is 1 hour away and the patient is too unstable and will not survive transport. 

PUSH THE LYTICS! 

Thrombolytics can be life saving in this situation. The patient was administered thrombolytics and shortly after the lytics were administered, the systolic blood pressure rose to about 80mmHg with ongoing epinephrine infusion. The below ECG (ECG #4) was recorded.

ECG #4

Although the above ECG shows widespread and massive ST depression, these ischemic changes actually represent an improvement over the pre-thrombolytic ECG. (ECG #2). There is now some flow in the LMCA! 

This series of ECGs (ECG #1, #2 and #4) illustrate well that subtotal occlusion of the left main is usually associated with severe subendocardial ischemia (profound and diffuse ST depression), whereas an ECG recorded during total occlusion of the LMCA (ECG #2) will show widespread ST elevations. Complete LMCA occlusion is associated with clinical shock and/or cardiac arrest.

As mentioned above, some flow was restored in the left main coronary artery at the time of recording of ECG #4. Transport to a PCI-capable facility was arranged - and on arrival at the PCI centre, the patient maintained a mean arterial pressure (MAP) of 40-50 mmHg and was alert. His lactate was down to 8. The video below shows the coronary angiography. The image quality is not the best, but you can see the subtotal occlusion of the left main artery. 

Below is a still image with the red arrow indicating the subtotal LMCA stenosis.

Post PCI an intra-aortic balloon pump (IABP) was placed and a combination of norepinephrine and dobutamine was needed to maintain perfusion pressures. Pressors could gradually be tapered within 24 hours. The initial troponin I drawn in the local emergency department prior to transfer to PCI center was 42ng/L (ref < 34ng/L) NT-proBNP was 307ng/L (ref < 300ng/L) 

The below ECG was recorded 12 hours after PCI. There is sinus rhythm with a premature atrial contraction (P wave best seen in leads V1 and V2 superimposed on the T of the second QRS) The PAC conducts to the ventricle with a prolonged PR interval. The profound ST segment and T waves changes are gone. The bifasicular block persists

ECG #5
(12 hours after PCI)

High sensitivity troponin T 16 hours after admission measured 14.877ng/L  (this is a massive infarct!). NT-proBNP was 3753ng/L There was transient liver enzyme elevation as is common with acute shock. The patient spent a couple of days in the cardiac intensive care unit receiving treatment for acute heart failure and aspiration pneumonia. He was later transferred back to his local hospital neurologically intact and without serious sequela. Long term follow up is not available.

How did the Queen of Hearts do on today's ECGs? 

See the the below image with interpretation of ECG #1, #2, #4 and #5

Click here to sign up for Queen of Hearts Access.

See this post for 8 cases of total LM Occlusion:

How does Acute Total Left Main Coronary occlusion present on the ECG?

See this case and this case for more examples of ACS involving the LMCA

Learning points:

• LMCA occlusion carries a poor prognosis, most patients do not make it to the hospital. Those who make it to the ED usually have transient occlusions with reperfusion.
  
  
• Suspect LMCA with sudden shock and widespread ST elevations. 
  
  
• Some patients are too unstable for transfer. Thrombolytics can be life saving, the patient in today's case likely would not have survived had he not been given thrombolytic therapy

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MY Comment, by KEN GRAUER, MD (10/20/2024):

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Today's case marks a tale of gratifying results from astute management of a critically ill patient with cardiogenic shock that resulted from acute LMain occlusion.

• As per Dr. Nossen — it will not be often that emergency providers encounter patients with acute LMain occlusion — simply because survival of most of these patients is so limited. Today's case offers a unique opportunity to track the evolution of a patient during the process of ongoing LMain occlusion.

Before specifically commenting on 2 of the tracings from today's case — it is worth reviewing lessons learned regarding the ECG presentation of patients with acute LMain occlusion. To do this — I have excerpted in Figure-1, my summary of Dr. Smith's major conclusions regarding the ECG appearance of this situation. The KEY Take Home Points are as follows:

• There is no “single” ECG presentation for patients with acute LMain occlusion. Quite literally — You can see almost anything!
• The reason for this highly variable ECG presentation, is that multiple territories may be involved to varying degrees — making it impossible to predict how much ST elevation you will see — and how much opposing (reciprocal) ST depression will attenuate (if not completely cancel out) these initial ST segment vector forces.
• The ST-T wave appearance in lead aVR can be anything when there is acute LMain occlusion.

Figure-1: Reasons for the varied ECG presentation of acute LMain occlusion — excerpted from Dr. Smith’s 8/9/2019 post (This Table from My Comment in the January 16, 2020 post).

Application of Figure-1 to Today's CASE:

What I found so fascinating about today's case — is how dramatically the ECG picture changed within the space of 15 minutes (as shown in Figure-2) — with this being the short amount of time that passed between the recording of the first 2 tracings in today's case.

• As per Dr. Nossen — today's initial ECG (LEFT tracing in Figure-2) shows sinus bradycardia with QRS widening due to bifascicular block (RBBB/LAHB).
• There is marked, diffuse ST segment depression in ECG #1. To facilitate distinguishing between the end of the QRS and the beginning of the ST segment — I highlight the J-point with BLUE arrows. 
• Marked ST elevation is seen in lead aVR (to the right of the RED arrow in this lead).
• As we have noted on many occasions — this ECG picture of diffuse ST depression with ST elevation in lead aVR suggests DSI (Diffuse Subendocardial Ischemia). That said, more than just DSI — ECG #1 also demonstrates the bifascicular block (of RBBB/LAHB) that is so commonly seen in association with acute LAD occlusion.
• Another interesting feature seen in ECG #1 — is that lead III shows a nearly isoelectric baseline. I suspect this is the result of the interplay between electrical forces favoring ST elevation and ST depression.
• 
  
• To Emphasize: DSI does not indicate acute infarction. And although severe underlying coronary disease is often the cause — non-coronary causes may be seen (See My Comment in the March 1, 2023 post for the common causes of DSI ). That said — we have cath confirmation in today's case of subtotal LMain occlusion (which is consistent with the findings in ECG #1).

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And then, 15 minutes later in today's case — this patient was in cardiogenic shock. 

• It is worth taking a moment to compare lead-by-lead what the changes are that occur in the form of ST elevation and ST depression between ECG #1 and ECG #2.
• As per Dr. Nossen — this sudden deterioration in the patient's clinical condition, in association with the ST-T wave changes now seen in ECG #2 — almost certainly indicates evolution to complete LMain occlusion (even though cardiac catheterization done a short time later showed subtotal but not complete occlusion).
• 
  
• PEARL: As noted in the 1st sentence of the Table in Figure-1 — a major reason why the limited data that we have on what the ECG "looks like" with acute LMain occlusion is so varied — is that we never know for certain what the state of the artery was at the time the ECG was recorded (which may be different than the state of the artery when the catheterization was done).
• In particular — Isn't it interesting how the ST-T wave appearance in lead aVR is totally reversed from the marked ST elevation seen with DSI (in ECG #1) — to marked ST depression once LMain narrowing becomes complete (in ECG #2). No wonder the limited data we have shows such variation in the ST-T wave appearance of lead aVR with LMain "occlusion".

Figure-2: Comparison between the first 2 ECGs in today's case. RED arrows are placed at the J-point for judging ST elevation; BLUE arrows at the point for ST depression.

More "Shark-Fin" . . .  

The 1st time I saw "Shark Fin" ST elevation (and "Shark Fin" ST depression) — I had no idea what I was seeing. With practice — this mimic of QRS widening becomes easy to recognize. 

• Today's case adds the extra feature of Shark Fin ST elevation on an already widened QRS complex (because of the RBBB/LAHB). That said — recognition of marked ST elevation or depression remains easy once the J-point is identified (colored arrows in Figure-2).

NOTE: For those wanting more practice recognizing Shark Fin ST-T wave changes — we've shown cases of this entity in the following ECG Blog posts (among others): 

• In the June 11, 2018 post —
• In the October 4, 2019 post —
• In the November 22, 2019 post —
• in the January, 24, 2020 post —
• in the February 16, 2020 post —
• in the April 25, 2020 post —
• in the May 19, 2020 post —
• in the September 27, 2023 post —
• in the May 3, 2024 post —
• 
  
• And — this case of a Shark-Fin-like mimic (My Comment in the August 23, 2024 post).

 

What are treatment options for this rhythm, when all else fails?

Written By Magnus Nossen — with edits by Ken Grauer and Smith.

The patient in today’s case is a previously healthy 40-something male who contacted EMS due to acute onset crushing chest pain. The pain was 10/10 in intensity radiating bilaterally to the shoulders and also to the left arm and neck. The below ECG was recorded. 

The ECG shows obvious STEMI(+) OMI due to probable proximal LAD occlusion. 

The magnitude and distribution of ST elevation and ST depression is very concerning. There is massive ST elevation in lead V1 and V2 with diminishing degree of ST elevation toward V4. Leads II, III, aVF and V6 all show a large amount of ST depression. Lead I shows slight STE, and a hyperacute T wave — while lead aVL has significant ST elevation. This ECG does not have the typical ST-vector of an LAD occlusion. 

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See below for Ken Grauer Comment on the initial ECG:

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Continuation of the case: The patient was accepted for primary PCI. He arrived ill-appearing, hypotensive with cool and clammy skin. He was taken immediately to the cath lab. Below is the initial angiography image. It shows a proximal LAD occlusion, in conjunction with a subtotally occluded LMCA (Left Main Coronary Artery). The RCA was occluded proximally with retrograde filling from the LCx. You can see the how poorly the contrast is defined on the below image signifying severely decreased contrast flow through the stenotic LMCA.

You can see Left Main and Proximal LAD obstruction, but with some flow, which is saving this patient's life.

Immediately after contrast injection into the LMCA, the patient had circulatory collapse, with a precipitous drop in blood pressure. Epinephrine infusion was begun.  An Impella device was placed to maintain cardiac output and perfusion pressures.  Subsequent PCI of the LMCA and LAD was performed. Below is the post-PCI angio image (the orientation is slightly different explanining why now the LAD is shown below the LCx). The image shows the impella device in place. After PCI — there was acceptable flow in the LM, LAD and LCx arteries.

Angiography: 

• LMCA — 90-99% osteal stenosis. 
• LAD — 100% proximal occlusion; with 70-89% mid-vessel narrowing. 
• LCx — 50-69% stenosis of the 1st marginal branch; with 100% distal LCx occlusion. 
• RCA — 100% proximal occlussion.

The patient in today’s case presented in cardiogenic shock from proximal LAD occlusion, in conjunction with a subtotally stenosed LMCA. The RCA was occluded proximally — and was being filled retrograde from the left-sided vessels. Upon contrast injection of the LMCA, the patient deteriorated, as the LMCA was severely diseased and flow to all coronary arteries (LAD, LCx and RCA) was compromised. 

Following PCI — the patient became uncooperative and agitated, and needed intubation. Over the next couple of days the patient was weaned off of mechanical circulatory support. Inotropic medication was continued. Troponin T peaked at 38,398 ng/L ( = a very large myocardial infarction)

The echo images below were obtained on the day of presentation after PCI. Cardiac function is poor, with akinesis of the LAD territory. The impella catheter is seen in the left ventricular outflow tract (LVOT).

Below is a repeat Echo of the left ventricle in the apical 4-chamber view. (This was recorded a number of days later). By comparison — you can appreciate the difference in contractility in the LAD territory, and overall systolic performance of the LV.

The patient was extubated on Day-3 of the hospital stay. Unfortunately, he required re-intubation a few days later due to respiratory distress from severe bilateral pneumonia. The stay in the cardiac intensive care unit (CICU) was further complicated by sepsis, delirium, GI bleeding, and anuric renal failure with need for renal replacement therapy.

The patient improved, and on Day-11 of the hospital stay — he was off inotropes and on a small dose of a ß-blocker. However, he suddenly developed a series of malignant ventricular arrhythmias. This progressed to electrical storm, with incessant PolyMorphic Ventricular Tachycardia (PMVT) and recurrent episodes of Ventricular Fibrillation  (VFib). He required multiple defibrillations within a period of a few hours. Below are printouts of some of the arrhythmias recorded. What do you think?

The above ECG shows a run of PMVT that terminates on its own. 3 sinus-conducted beats ensue — before another run of  PMVT occurs. Both episodes are initiated by an "R-on-T" phenomenon. The sinus conducted beats show a completed anterior wall MI, with QS waves in the precordial leads. There is no definite evidence of acute ischemia. (ie, No excessive ST elevation or hyperacute T waves). QRS morphology in leads V1-thru-V3 manifests features resembling Brugada morphology. 

The tracing below followed:

This 12-lead ECG above shows another episode of PMVT. This time, the arrhythmia did not spontaneously terminate — but rather degenerated to VFib, requiring  defibrillation.

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Discussion: 

Today's patient manifests multiple episodes of PMVT and VFib. Sinus-conducted beats in the above examples show a normal QTc interval. This is an important finding related to the etiology and treatment of these malignant arrhythmias — since by definition, PMVT with a prolonged QTc is classified as Torsades de Pointes (and entails different treatment recommendations).

The schematic grouping below reviews classification of PMVT types: 

In today's case — the sinus-conducted beats prior to and between the episode of PMVT show evidence of completed anterior wall MI. That said — there is no evidence on ECG of re-occlusion of the infarct artery. In both tracings — an exceedingly fast PMVT is documented. The arrhythmia starts with a PVC having a short coupling interval. The R-R intervals of the VT are less than 200ms and ventricular rate > 300 bpm! (Distinction of PMVT vs VFib is an academic one in this case). Both PMVT and VFib occurred multiple times. Some episodes of PMVT would terminate spontaneously — but on many occasions, the PMVT degenerated to VFib, requiring defibrillation. 

The situation in today's case was of a critically ill young man with an exceedingly electrically unstable myocardium. Simply stated — the patient was having recurrent PMVT without QTc prolongation, and without evidence of ongoing transmural ischemia. (If there had been ECG findings indicating reocclusion of the artery — an angiogram would have been warranted). Some residual ischemia in the infarct border might still be present. There was no evidence bradycardia leading up to the runs of PMVT (as tends to occur with Torsades). If there had been — a temporary atrial pacemaker could have been considered as a way of increasing the heart rate to suppress a bradycardia-dependent arrhythmia ("overdrive pacing"). 

QUESTION:

• How will you handle this arrhythmia given the clinical scenario?

NOTE: This patient was already on a low-dose ß-blocker. IV Amiodarone was ordered — but did not reduce the frequency of ventricular ectopics or the number of VT episodes. The patient continued in arrhythmic storm with recurring PMVT and VFib episodes. 

• What are additional treatment options?

Our Thoughts:

Incessant PMVT is notoriously difficult to treat. It can be resistant to cardioversion — and often responds poorly to antiarrhytmic drugs when compared to monomorphic VT. A high-dose, short-acting ß-blocker should be tried. An ultra short-acting ß-blocker such as Esmolol, can be given as by IV infusion (ie, as a loading dose of 500mcg/kg — followed by an infusion of 50mcg/kg/min). Due to its short half-life, the drug easily be titrated and/or discontinued if not tolerated. Intubation and sedation with propofol is warranted if not already done to decrease sympathetic drive and discomfort to the patient. 

Today's patient was hypotensive and recently weaned off of inotropic support. IV Metoprolol was given without apparent effect on ectopy incidence and arrhythmia. The patient was already intubated and sedated. The decision was made to try Quinidine (as this case was felt to represent conditions consistent with Quinidine-responsive PMVT).

Quinidine-Responsive PMVT — is a well described entity (Viskin et al — Circulation 139(20), 2019 — and — Viskin et al —  Circulation 144(10), 2021) — that occurs during the "healing phase" after acute MI, in which the arrhythmia originates in Purkinje cells (which explains why this ventricular arrhythmia tends to be so responsive to Type 1A drugs like Quinidine). Mechanistically — Quinidine is a strong blocker of the transient outward potassium current. This is relevant because transient outward potassium current channels are highly expressed in Purkinje fibers.

• In contrast, conventional treatment of this type of ventricular arrhythmia with agents including ß-blockers, Amiodarone, Magnesium and Lidocaine — all-too-often fails. 
• Studies of patients with coronary artery disease who developed arrhythmic storm with episodes of PMVT following MI — show arrhythmias indistinguishable from those reported in this case. In such cases — radiofrequency ablation of ectopic beats triggering malignant ventricular arrhythmias was needed for control of arrhythmic storm because the antiarrhythmic medications tried were ineffective (Marrouche et al — JACC 5;43(9): 1715-20, 2004).
• Of interest — the ectopic beats triggering PMVT/VFib in such studies were often mapped to endocardial sites displaying Purkinje potentials within the myocardial scar — suggesting potential responsivity to a 1A agent (Nogami — Pacing Clin Electrophysiol 34(8): 1034-1049, 2011).

Today's patient was started on oral Quinidine-Sulfate (400mg x 4/day) — with a rapid cessation of all PMVT and VFib episodes. In a case like today’s all contraindications are relative if the drug you are giving is effective as the underlying entity you are treating is deadly if not controlled.

The most common side effects of Quinidine is hypotension and QTc prolongation. These are also the most commonly reported findings in toxic overdoses with ventricular arrhythmias being reported as the leading cause of death. Information is scarce when it comes to what constitutes a toxic dose. Numbers given are based mostly on case reposts. Lethality reported from ingestion of 5 grams in a toddler while survival after ingestion of 8 grams has been reported in an adolescent.

What About Procainamide? 

The PROCAMIO study included hemodynamically stable patients in VT. In this study — Procainamide was superior to Amiodarone for terminating monomorphic VT, as well as having fewer adverse effects than Amiodarone (Ortiz et al — Eur Heart J 1;38 (17): 1329-1335, 2017).

Procainamide, like Quinidine is a Type 1A antiarrhythmic. Because Procainamide is not marketed in Norway — I have no experience using this agent. 

• In the United States (and in other locations where Quinidine is not readily available) — Procainamide would seem the recommended choice to consider for arrhythmias like those in today's case, especially if not responding to the usual antiarrhythmic regimen.

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Smith comment: I agree with starting with a beta blocker such as esmolol, since this is likely to be a hyper-catecholaminergic state. Another approach is sympathetic chain (stellate ganglion) blockade if you have the skills to do it: it requires some expertise and ultrasound guidance. If these do not work, the a type 1a anti-dysrhythmic is certainly a reasonable choice (procainamide, or in Norway, quinidine).  Administration of Procainamide is 10-17 mg/kg at 20 mg/min.  A 1000 mg dose will take 50 minutes.)  One should infuse until:  1) good effect, or 2) hypotension or 3) increase in QRS duration to 1.5x baseline (this is what most recommend but seems like far too much QRS widening to me)

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See these articles and this graphic:

1. A Multicenter Study of Stellate Ganglion Block as a Temporizing Treatment for Refractory Ventricular Arrhythmias 

2. Stellate ganglion blockade for the management of ventricular arrhythmia storm

CASE Conclusion:

Today's patient ultimately made a full recovery — and was discharged home. An ICD (Implantable Cardioverter Defibrilator) was placed prior to discharge. Quinidine eventually was discontinued due to development of hemolytic anemia. Additional follow-up was not available. 

Learning points 

• PMVT following MI can be very difficult to treat. Quinidine (or perhaps Procainamide if Quinidine not available) might be considered as an option for refractory cases, especially if other methods tried were not effective. 
  
  
• When dealing with recurrent episodes of PMVT — attention to the QTc interval of sinus-conducted beats is essential for distinction between Torsades vs other types of PMVT. 

See this article on polymorphic VT

This review of anti arrhythmic drugs is worth a read

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MY Comment, by KEN GRAUER, MD (7/21/2024):

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Intriguing post by Dr. Nossen — in which he discusses a case of incessant VT with multiple PMVT/VFib episodes that occurred post-MI, in a patient with a normal QTc who failed to respond the usual antiarrhythmic treatment — but which immediately responded to treatment with Quinidine! (See my Addendum Note below).

• I focus my comment on the initial ECG in today's case — which I've reproduced and labeled in Figure-1. 

The dramatic nature of the ECG in Figure-1 is immediately apparent. I'll draw attention to the following:

• The pattern of at the very least proximal LAD occlusion — is evident from marked ST elevation beginning in lead V1 — attaining peak amplitude in lead V2 — and continuing until lead V4. 
• Proximal left coronary artery occlusion is supported from limb lead findings of marked ST elevation in lead aVL (with a hyperacute ST-T wave in lead I) — and even more dramtic reciprocal ST depression in each of the inferior leads.
• Cath findings shown above in Dr. Nossen's discussion confirm multi-vessel disease, including 90-99% osteal stenosis of the LMCA. As we've often emphasized on Dr. Smith's ECG Blog — it is rare in practice to see LMCA occlusion, because most such patients die before reaching the hospital. Nevertheless, this entity does occur on occasion — and it is important to appreciate its ECG presentation. As I review in My Comment in the January 16, 2020 post of Dr. Smith's ECG Blog (and have reproduced in Figure-2 below) — the ECG of patients with acute LMCA occlusion may be varied. Today's extensive ST-T wave elevation and depression (with ST elevation in lead aVR) — is consistent with one of these patterns.  

While clearly not needed for diagnosis — today's initial ECG is an instructive tracing in that it illustrates:

• Precordial "Swirl" — for which Drs. Meyers and Smith illustrate 20 example cases vs "look-alikes" of Swirl (with my synthesis of "Swirl" ECG findings in My Comment on that post) from October 15, 2022. In Figure-1 from today's case — the coved ST elevation in lead V1 vs the nearly mirror-image opposite ST depression in lead V6 present as marked an example of acute septal ischemia as I've encountered.
• T-QRS-D (Terminal-QRS-Distortion) — with my RED arrows highlighting as marked an example of T-QRS-D as I've encountered. Drs. Smith and Meyers emphasize that this ECG finding is diagnostic of acute OMI when seen in leads V2 and/or V3 (and probably also in lead V4) — though the picture of T-QRS-D seen in lead aVL of Figure-1 clearly tells a similar story (See My Comment at the bottom of the page in the November 14, 2019 post in Dr. Smith's ECG Blog — for illustrative description of T-QRS-D).

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

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Below in Figure-2 — I've reproduced the Table from My Comment in the January 16, 2020 post of Dr. Smith's ECG Blog that highlights potential ECG findings of acute LMCA occlusion.

Figure-2: Reasons for the varied ECG presentation of acute LMain occlusion — excerpted from Dr. Smith’s 8/9/2019 post (See text).

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Addendum Note: 

Quinidine has a long history of use to treat cardiac arrhythmias and severe malaria. My understanding is that the IV formulation of Quinidine is no longer readily available (if manufactured at all) in the US. In today's patient (who was treated in Norway) — Oral Quinidine was used.

• Oral Quinidine is available in sulfate or gluconate formulations. Rapid-acting oral formulations begin to work within 1-3 hours. The most common adverse effects are GI (diarrhea, nausea, vomiting) — and these are usually drug limiting. 
• Principal adverse cardiac effects of Quinidine include QRS widening and QTc prolongation. With longterm use there may be — bradycardia, AV conduction defects and risk of Torsades de Pointes (especially in patients also on Digoxin). Other adverse effects may be seen (Today's patient ultimately stopped the drug due to hemolytic anemia).
• Although used extensively as an antiarrhythmic agent in the past in the U.S. — the adverse effect profile of Quindine, and the greater efficacy of other antiarrhythmic agents have limited longterm Quinidine use (at least in the U.S.) for this purpose. That said — the drug worked wonders for treatment of today's patient! (who had otherwise resistant ventricular arrhythmias!).

 

IV Procainamide is used in the United States. 

• During the years that I used the drug — the dosing regimen I favored was to give 100 mg IV slowly over 5 minutes (at ~20 mg/minute) — until one of the following end points is reached: i) The arrhythmia is suppressed; ii) Hypotension occurs; iii) The QRS widens by 50%; — and/or — iv) A total loading dose of 500-1,000 mg has been given. This may be followed with IV infusion at 2 mg/minute (1-4 mg/minute range).
• NOTE: Although the maximal rate for IV Procainamide infusion has been limited to 50 mg/minute — adverse effects (ie, hypotension, bradycardia, QRS widening) are less at slower infusion rates (ie, of ~20 mg/minute).