Saturday, July 6, 2024

SAVE- DRAFT- Has ALL STUDIES that DOCUMENT OMI Paradigm (7-8.1-2024)-SAVE


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MY Comment, by KEN GRAUER, MD (7/6/2024):

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Today’s post by Dr. McLaren is an important one — in that emphasizes by means of 2 clinical example cases, shortcomings of the outdated and problematic STEMI paradigm.
  • Regular followers of Dr. Smith’s ECG Blog will be well familiar with scores of cases we’ve presented illustrating the trials and tribulations of the millimeter-based STEMI paradigm. All-too-many clinicians (including cardiologists) — remain “stuck” on this STEMI paradigm out of force of habit and failure to appreciate the now well-defined pathophysiology of what happens during the course of an evolving ACO (Acute Coronary Occlusion) — which is what we call an OMI (Occlusion Myocardial Infarction).
  • As per the 2 cases presented today by Dr. McLaren — the consequences of this current fallacious approach are many and far-reaching.

An expanding literature has now convincingly shown the following: 
  • Rigid adherence to millimeter-based STEMI criteria misses at least 1/3 of OMIs (Meyers, Smith et al — Ann Emerg Med 74(4): S26, 2019 — and — Meyers, Smith et al — Int J Cardiol Heart Vasc, 2021)
  • We know STEMI criteria are problematic — because clinicians trained to assess other ECG parameters (instead of relying solely on a given amount of millimeters of ST elevation) — are able to accurately identify OMIs that adherence to STEMI criteria will miss (McLaren, Meyers, Smith — Canad J Emerg Med 24: 250-255, 2022) — and — Westafer L — ACEP Now, Dec., 2022 — and — Kontos et al; 2022 ACC Expert Consensus — JACC 80(20):1925-1960, 2022).
  • More than simple failure to identfy STEMI-/OMI+ cases — adherence to the outdated STEMI paradigm may result in delayed diagnosis of many patients with acute coronary occlusion who did not manifest enough ST elevation to “qualify” for a STEMI at the time they were seen.
  • The clinical reality of this delayed diagnosis distorts data in the literature by overestimating the accuracy of the STEMI paradigm. This happens because some patients who are STEMI- initially — eventually do develop enough ST elevation to “qualify” as a STEMI — yet delay by a period of hours (and sometimes delay for up to a day or more!) — means significant loss of viable myocardium in these OMI+ patients, who should have been recognized and treated with PCI long before they finally developed "enough" ST elevation to qualify as a STEMI (McLaren, Meyers, Smith — J Electrocardiol 76: 39-44, 2023).
  • Another way in which the current literature is distorted in favor of the failed STEMI paradigm — is that there are no false negatives among STEMI- patients (McLaren, Meyers, Smith — J Electrocardiol 76: 39-44, 2023). This is because failure to satisfy millimeter-based STEMI criteria is erroneously accepted as the absence of acute coronary occlusion — and then misclassified as a "NSTEMI". Unfortunately, this methodological flaw perpetuates false conclusions about the overrated accuracy of STEMI criteria.

Clinicians and the STEMI Paradigm both ignore OMI Pathophysiology:
Based on cases submitted to us at Dr. Smith’s ECG Blog — the overwhelming majority of clinicians (including cardiologists) ignore the basic pathophysiology of what happens during the course of an acutely evolving OMI. Consider the following:
  • Not uncommonly — the “culprit” artery may suddenly occlude — then spontaneously reopen (sometimes prior to the patient seeking medical attention) — and on occasion, continue to open and close spontaneously a number of times. Interpreting serial ECGs that are correlated to the patient’s History — can tell us the state of the “culprit” vessel (thereby helping us greatly to understand and interpret ECGs that may not be showing frank ST elevation).
  • With acute occlusion — the patient typically develops CP (Chest Pain) — and — ST segments over the area of infarction tend to elevate, while in opposite areas of the heart, there is typically reciprocal ST depression.
  • With spontaneous reopening of the “culprit” vessel — CP decreases (or resolves) — and — ST segment deviations (elevation and depression) improve or normalize.
  • KEY Point: What spontaneously opens — may just as easily (and at any time) spontaneously reclose. It is for this reason that even if a patient who had ST elevation is now pain-free and now without ST elevation — that prompt cath with PCI is still indicated, because that patient may still at any time spontaneously reocclude.
  • CAVEAT: Even a recent STEMI may fail to show ST elevation at the time the ECG you are looking at was done IF — prior to this, there has been an ongoing process of intermittent occlusion, followed by spontaneous reopening. Remember that in between the phase of acute ST elevation and development of reperfusion T waves (with T wave inversion) — may come a phase of pseudo-normalization, in which the ECG may look surprisingly unremarkable.
  • Many of these patients with positive troponin and unremarkable or nonspecific changes on ECG at the time their tracing was recorded — are misdiagnosed as having had a "NSTEMI" — when in fact they had acute coronary occlusion. Failure to correlate symptoms with each ECG (stemming from a failure to appreciate the pathophysiology described above, of an acutely evolving OMI) is the reason for gross overuse of the term, "NSTEMI".
  • Finally, depending on WHEN the cath was done during the course of a “transient” STEMI — the “culprit” artery may not always still be occluded at the time of cardiac catheterization (ie, a less than totally occluded artery on cath might still be the "culprit" artery that caused the infarction).







No false negatives 

Why so many problems?

Current paradigm ignores the basic pathophysiology of what happens during the course of an acutely evolving OMI.
— Almost uniform ignoring of the simple correlation between Sx and the timing of each serial ECG. Why important? Because this simple correlation provides invaluable insight into the likely status of the “culprit” vessel — which may explain why ST-T wave changes are only modest (pseudonormalization)


None of these were considered, and there have been no further placebo-controlled randomized reperfusion trials of any kind for AMI, much less for other ECG findings of AMI or for PCI vs. placebo or for immediate vs. next day PCI for either OMI or for STEMI. Instead, decades later, we are still basing the reperfusion decision almost entirely on this dichotomous finding of STE or not. The 4th universal definition of MI defines STEMI as STE in 2 contiguous leads with at least 1 mm measured at the J point, except for V2-V3 which vary by age/sex (1.5 in women, 2 in men >40 and 2.5 in men <40) [5]. This is based on 1220 patients, 248 of whom were diagnosed with AMI by elevation of Creatine Kinase-MB fraction, from a 1980's cohort; it is not based on angiographic outcomes or any other proof of OMI [6].

STEMI criteria are promoted as a simple and effective way to teach and identify acute coronary occlusion, but fail in both respects. Interrater reliability and sensitivity of physician identification of STEMI is poor, including among interventional cardiologists [7]. Automated interpretation is no better: a prospective validation of STEMI criteria found that computer interpretation of STEMI criteria was only 21% sensitive for OMI based on the first ECG and 30% based on serial ECGs, while blinded cardiologists were only 49% sensitive. In total, STEMI criteria had 37% false positive and 70% false negative rates [8].

Furthermore, the STEMI paradigm perpetuates these failures by denying the possibility of false negatives. We have called this the “no false negative paradox”. If the ECG meets STEMI criteria and there is OMI, this is a true positive; and if there is no OMI, it is a false positive. If the ECG does not meet STEMI criteria and there is no OMI, then it is a true negative. However, if the ECG does not meet STEMI criteria and there is OMI, i.e. STEMI(−)OMI, it is not considered a false negative because it is by definition a “NonSTEMI.” No matter how deadly the clinical outcome, no matter how much other clinical evidence of OMI were present other than STE, no matter how much benefit the patient may have received by earlier diagnosis and reperfusion, a patient with NSTEMI is treated as though delayed management is almost always justified because the paradigm excludes the possibility of a false negative. While NSTEMI guidelines recommend immediate invasive strategy for patients with hemodynamic or electrical instability or recurrent/refractory chest pain despite medical management [9], a recent study found this was only followed in 6.4% of very high risk NSTEMI patients [10].

This problem has deadly results. A meta-analysis of >40,000 NSTEMI patients with their first AMI found that, on next day angiogram, 25% had a persistent total 100% occlusion, without collateral circulation, and a significantly greater mortality rate compared to those with an open artery, and in spite of the fact that those with occlusion were on average 15 years younger [11].



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MY Comment by KEN GRAUER, MD (10/14/2020):

http://hqmeded-ecg.blogspot.com/2020/10/dynamic-st-elevation.html

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Insightful case showing 4 serial tracings during evolution of a STEMI in which the “culprit” artery was reperfusing and re-occluding. Although I limit my comments below to the initial EMS ECG that was done in the field ( = ECG #1) — I wanted to first reemphasize some important points brought out by Dr. Smith’s discussion above.

  • The History is essential! The patient in this case was an older man with risk factors who described, “intermittent left-sided chest discomfort” over more than 1 day — with recurrence of this chest discomfort 2 hours prior to ECG #1. Awareness of this history greatly enhanced my insight at the time I interpreted this 1st ECG.
  • Not uncommonly — the “culprit” artery may suddenly occlude — then spontaneously reopen (sometimes prior to the patient seeking medical attention) — and on occasion (such as in today’s case) — continue to open and close spontaneously a number of times. Interpreting the serial ECGs in today’s case, in association with this patient’s History  tells us this is what was happening.
  • Even a “recent” STEMI may fail to show ST elevation at the time the ECG you are looking at was done IF — prior to this, there has been an ongoing process of intermittent occlusion, followed by spontaneous reopening.
  • Depending on WHEN the cath was done during the course of a “transient” STEMI — the “culprit” artery may not always still be occluded at the time of cardiac catheterization.
  • It may be difficult to determine the “culprit artery” from the initial ECG if the patient has multi-vessel disease (as did the patient in today’s case). In such instances when ECG findings may not be localized — the indication for cath may be cardiac chest pain with ischemic findings on ECG, even if no specific “culprit artery” is suggested on the ECG.
 
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Figure-1: I've labeled atrial activity in today's ECGs.



McLaren, Meyers, Smith — J Electrocardiol 76: 39-44, 2023
What Should ECG Deep Learning Focus On? The Dx of Acute Coronary Occlusion!

https://www.sciencedirect.com/science/article/pii/S0022073622002023

STEMI vs NSTEMI

The ST Elevation (STE) Myocardial Infarction (STEMI) vs. Non-STEMI paradigm has been the universal definition and approach for AMI since the year 2000, when it formally replaced the previous Q-wave vs. non-Q-wave paradigm [3]. According to this paradigm, STE, as defined in the Fourth Universal Definition of MI, is the single marker which determines whether a patient gets immediate or delayed treatment for acute coronary occlusion. STE is inappropriately accepted as a surrogate for this emergency diagnosis, based on conventional wisdom and dogma.

Where does this dogma come from? The Fibrinolytic Trialists Therapy meta-analysis published in the Lancet in 1994, composed of all nine large (at least 1000 patients) randomized, placebo-controlled thrombolytic trials for AMI from the 1980s [4]. Only 4 of the 9 trials required STE (of varying amounts, without specifying the measurement method), and in the remaining 5 trials, no ECG findings were required. Streptokinase was the treatment in 7 trials, and 38% of patients had greater than six hours of chest discomfort despite the fact that the efficacy of thrombolytics drops off sharply after just a few hours [4]. Without any subgroup analysis into ST Elevation or ST depression, thrombolytics reduced mortality at one month, with a number needed to treat of 56. Subgroup analysis found that thrombolysis in unspecified STE and bundle branch block (BBB) had mortality benefit, whereas unspecified ST depression (STD) showed a non-significant mortality harm. It also found no benefit of reperfusion therapy in patients with inferior ST elevation. The universal simplistic and thus erroneous conclusion from this data was that STE is the way to determine which patients need emergent reperfusion.

But this is only true if ECG interpretation is crude, treatment is late, and streptokinase is the treatment. What about acute Q waves, terminal QRS distortion, subtle ST elevation, isolated ST depression, or hyperacute T-waves? What about QRST morphology, or QRS/ST-T proportionality? In LBBB and ventricular paced rhythm, which of the cases have OMI and which do not? How about all the pseudo- STEMI patterns which mimic STEMI? What about mortality using treatment other than streptokinase, such as percutaneous coronary intervention (PCI), or about accounting for the timing of treatment?

None of these were considered, and there have been no further placebo-controlled randomized reperfusion trials of any kind for AMI, much less for other ECG findings of AMI or for PCI vs. placebo or for immediate vs. next day PCI for either OMI or for STEMI. Instead, decades later, we are still basing the reperfusion decision almost entirely on this dichotomous finding of STE or not. The 4th universal definition of MI defines STEMI as STE in 2 contiguous leads with at least 1 mm measured at the J point, except for V2-V3 which vary by age/sex (1.5 in women, 2 in men >40 and 2.5 in men <40) [5]. This is based on 1220 patients, 248 of whom were diagnosed with AMI by elevation of Creatine Kinase-MB fraction, from a 1980's cohort; it is not based on angiographic outcomes or any other proof of OMI [6].

STEMI criteria are promoted as a simple and effective way to teach and identify acute coronary occlusion, but fail in both respects. Interrater reliability and sensitivity of physician identification of STEMI is poor, including among interventional cardiologists [7]. Automated interpretation is no better: a prospective validation of STEMI criteria found that computer interpretation of STEMI criteria was only 21% sensitive for OMI based on the first ECG and 30% based on serial ECGs, while blinded cardiologists were only 49% sensitive. In total, STEMI criteria had 37% false positive and 70% false negative rates [8].

Furthermore, the STEMI paradigm perpetuates these failures by denying the possibility of false negatives. We have called this the “no false negative paradox”. If the ECG meets STEMI criteria and there is OMI, this is a true positive; and if there is no OMI, it is a false positive. If the ECG does not meet STEMI criteria and there is no OMI, then it is a true negative. However, if the ECG does not meet STEMI criteria and there is OMI, i.e. STEMI(−)OMI, it is not considered a false negative because it is by definition a “NonSTEMI.” No matter how deadly the clinical outcome, no matter how much other clinical evidence of OMI were present other than STE, no matter how much benefit the patient may have received by earlier diagnosis and reperfusion, a patient with NSTEMI is treated as though delayed management is almost always justified because the paradigm excludes the possibility of a false negative. While NSTEMI guidelines recommend immediate invasive strategy for patients with hemodynamic or electrical instability or recurrent/refractory chest pain despite medical management [9], a recent study found this was only followed in 6.4% of very high risk NSTEMI patients [10].

This problem has deadly results. A meta-analysis of >40,000 NSTEMI patients with their first AMI found that, on next day angiogram, 25% had a persistent total 100% occlusion, without collateral circulation, and a significantly greater mortality rate compared to those with an open artery, and in spite of the fact that those with occlusion were on average 15 years younger [11].

The failure of STEMI criteria has led to attempts to broaden the paradigm to include “STEMI equivalents”, “semi-STEMIs” or “subtle STEMIs.” Yet these terms have no universal meaning, are never mentioned in the ACC/AHA guidelines, and in actual practice are ignored by cardiologists. These terms also perpetuate the cognitive bias inherent in the term “STEMI,” with its focus on ST Elevation. The STEMI paradigm leads providers to believe that STE is a valid surrogate marker of OMI, to believe that isolated ST segment amplitudes out of QRS context are all that matter, and that other ECG findings of OMI are irrelevant, when in fact the entire QRST, including all of the relative amplitudes and durations between the QRS and the ST-T are critical. The STEMI/NSTEMI false dichotomy prevents us from learning that all ECG findings are inherently proportional, which explains why subtle STE not meeting STEMI criteria can be diagnostic, while STE of greater amplitude than STEMI criteria can be present without ischemia. Just as disturbing, “STEMI” makes providers believe that OMI, as a disease process, is almost entirely defined and managed by the electrocardiogram; in fact, the ECG may be entirely nondiagnostic in the presence of OMI, and thus other modalities may be necessary for the diagnosis.

The STEMI paradigm prevents improvement in understanding of OMI, limits research on the ECG in AMI and research into ECG algorithms, and stifles evolution of the AMI paradigm. To our knowledge, no study of automated ECG algorithms has used an OMI study group; rather, studies of the accuracy of automated ECG interpretation tools invariably start by looking at a cohort of STEMI patients as the study group; thus, they begin with a group of true positives without any false negatives.

For all these reasons, the term “STEMI” is an important cause of the limitations of our current paradigm, and we must reframe the paradigm if we are to understand OMI and maximize the benefit of reperfusion for our patients. In the STEMI paradigm, the test (STE) is the definition of the pathology (OMI), so reperfusion therapy is based on presence or absence of STE on the ECG rather than presence or absence of underlying OMI. Instead we propose a new paradigm based on that actual underlying pathology: Occlusion MI (OMI) [12].

How can we identify OMI? Contrary to the STEMI paradigm, OMI is not defined by the ECG: refractory ischemia is an indication for urgent angiography even with a normal ECG, a recommendation made by current NSTEMI guidelines [9] but rarely followed [10]. ECGs are very insensitive for NOMI, but they don't need to be sensitive because urgent reperfusion is not necessary. We can therefore wait for a delayed diagnosis by use of troponin and delayed angiography/PCI for NOMI, because there is no ongoing ischemia. The exception is an occluded artery which has reperfused and has very unstable thrombus putting the artery at high risk of re-occlusion. Fortunately, ECGs, if read by true experts, are very sensitive for OMI and for reperfused occlusions, both of which identify patients requiring urgent angiography regardless of the initial troponin level [16,17]. Similarly, while most patients with unstable angina can wait for delayed angiography, ECG signs of reperfusion can identify those with an occlusive thrombus that rapidly spontaneously reperfused before infarction but is at risk for reocclusion.

Because the ECG is an instantaneous indicator of acute coronary occlusion, it is the most rapid means of identifying OMI. Other modalities such as point of care ultrasound can complement subtle ECG findings [18]. However, we cannot rely on advances in high sensitivity troponin assays to rapidly identify STEMI(−)OMI. No matter how sensitive or rapid, troponin is a delayed marker of AMI that reflects damage from the precious previous hours. An initial negative troponin on a patient with acute chest pain cannot rule out OMI, and an elevated troponin cannot determine if the injury is due to occlusion [19].

How do we know that STEMI(−)OMI can be identified by expert interpretation? In the DIFOCCULT study, cardiologists trained in the OMI paradigm and blinded to the outcome identified 28% of “NSTEMI” as OMI, and those patients had mortality similar to STEMI patients and much higher than NSTEMI whose ECGs did not show occlusion [16]. In our study, emergency physicians trained in the OMI paradigm (one senior, and one junior, faculty) could identify OMI with twice the sensitivity as STEMI criteria without a loss of specificity (see Table 1) [17]. Even among ECGs identified by STEMI criteria, the experts identified OMI on ECGs recorded a mean of 3.0 h and median of 1.5 h earlier. If implemented in the real world, this would result in an additional salvage of myocardium, with attendant reduction in mortality and morbidity, but the current paradigm constrains such implementation. Seven critical findings were identified which helped to identify OMI: hyperacute T waves, pathological Q waves along with subtle STE, terminal QRS distortion, reciprocal STD and/or reciprocal T wave inversion, subtle STE not meeting criteria but with other features, any amount of primary STD maximal in V1–4, and any amount of STE in inferior leads with any STD/T wave inversion in aVL. See Table 2.


In other words, identifying OMI on ECG requires going far beyond the exclusive focus on ST segment millimeter criteria. First of all, the ECG needs to be interpreted in totality—including heart rate, the entire QRS complex (including acute Q wave, loss of R wave, loss of S wave), the ST segment (including subtle STE, or STD reciprocal to STE including posterior or subtle inferior or lateral), the T wave (including hyperacute T-waves or reperfusion T-wave inversion), and QT prolongation (a subtle but early sign of occlusion), and dynamic change. Hyperacute T-waves are identified by their “bulk” (total area under the curve), not their amplitude, and that bulk is in proportion to the QRS. Many OMI have multiple subtle abnormalities (note the percentages in Table 2 add up to far >100%) that in their totality add up to a diagnostic ECG in the eyes of an experienced interpreter, but are dismissed as “non-specific” by the current paradigm and those who follow it.

Secondly, ST/T changes need to be assessed in proportion to the QRS complex. This is crucial in differentiating OMI from other causes of STE, among them LAD OMI vs normal STE in leads V2-V4, anterior left ventricular aneurysmmorphology vs. LAD OMI, and LBBB/paced rhythm with or without OMI using the ST/S ratio in the Modified Sgarbossa criteria.

Neural network potential and pitfalls

ECGs offer a major opportunity for neural networks [23]. The CDC estimates there are 40 million ECGs recorded in the US per year, which is likely an underestimate. This includes at least 6.5 million US ED visits for chest pain alone, plus another 4 million clinic visits for chest pain, with many more additional ED visits for anginal equivalents such as dyspnea. If only 10% of patients with chest pain have acute AMI, half of whom have OMI, and half of these have STEMI(−)OMI, then 2.5% of patients with chest pain in the ED have STEMI(−)OMI – a “needle in a haystack.” Those with STEMI(−)OMI require immediate recognition and reperfusion, yet nearly all are missed by current automated interpretation and by the STEMI paradigm on which they are based. OMI is the deadly needle in the haystack, and neural networks could play an important role in finding them.

Most research on neural networks has been on rhythms, especially atrial fibrillation detection. This work is so critical because so much of atrial fibrillation is occult and ripe for screening with monitors that are intelligent. OMI is also “occult,” since only a tiny fraction of patients with chest discomfort or dyspnea have OMI, and thus unless its subtle features are instantly recognized by providers, it will be missed until it is too late. In the Emergency Department, rhythm problems on the ECG are relatively easy because the presence of a problem is obvious: the rhythm is fast, slow, or irregular. But when there is chest discomfort or dyspnea, most etiologies are either benign or can wait hours for a diagnosis. The subtle ECG findings of OMI are too difficult for widespread training of providers; only neural networks will be able to fill this void.

By examining ECGs in their totality and applying principles of proportionality, ECG experts can identify OMI with the same familiarity as individual faces. When we look at faces, we recognize them immediately, without measuring the eyes or nose. As with faces, strict measurements of ECGs (ST segments) are useless. Like facial recognition technology, deep neural networks offer the potential of making immediate recognition of OMI widely available and accelerating the paradigm shift.

There are a number of challenges in training and testing neural networks for OMI. We need to start with the right outcome measure for OMI. If neural networks are only designed based on the STEMI criteria they will continue to reinforce its failings. Studies using conventional algorithms [24] that are only based on STEMI databases and only designed to identify STEMI(+)OMI continue to ignore STEMI(−)OMI which is the subgroup with the greatest reperfusion delay.

As a corollary, the control groups must be appropriately chosen. Due to the vast number of Non-OMI ECGs, it is nearly impossible to study a consecutive population of chest pain. As discussed, only a tiny percentage of chest pain patients have STEMI(−) OMI, and thus there would need to be accurate coding of 50 cases without OMI for every case of OMI. Therefore case control studies are much more practical. Many studies of STEMI vs Not STEMI compare STEMI (+) OMI to all other classifications (see Fig. 1Fig. 2), and thus the control group is contaminated by STEMI (−) OMI [25]. Fig. 2shows the appropriate inclusion of control groups.


Secondly, we need to use serial and post-reperfusion ECGs to identify the underlying pathophysiology. OMI is a dynamic process, including reperfusion and re-occlusion, and ECGs on ED arrival do not represent the state of the artery by the time of the angiogram. Ideal research methods would go beyond brief coronary balloon occlusion studies by recording 12‑lead ECGs at the moment of natural thrombotic occlusion, with continuous monitoring during the course of occlusion, with or without alternating spontaneous thrombolysis and thrombus propagation, but ideal is not always possible. Many studies of algorithm diagnosis of STEMI use only one ECG from each patient. These methodologies ignore the dynamism of the ECG (and the practice of obtaining serial ECGs), with morphologies in constant flux due to the thrombus propagating and lysing, with various degrees of reperfusion and reocclusion. See Fig. 3Fig. 4.

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McLaren, Meyers, Smith, Chartier — Canad J Emerg Med 24: 250-255, 2022
From STEMI to Occlusion MI: Paradigm Shift and ED Quality Improvement

https://link.springer.com/article/10.1007/s43678-021-00255-z


Westafer L — Reperfusion Guidelines Finally Catch Up
Dec. 9, 2022 — ACEP Now

https://www.acepnow.com/article/the-reperfusion-guidelines-finally-catch-up/?singlepage=1&theme=print-friendly




Kontos et al — 2022 ACC Expert Consensus Decision Pathway — Acute CP in the ED
JACC 80(20): 1925-1960, 2022

https://www.jacc.org/doi/10.1016/j.jacc.2022.08.750


Meyers, Smith et al — Int J Cardiol Heart Vasc, 2021
Accuracy of OMI ECG Findings vs STEMI Criteria

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8065286/


Herman R — Powerfl Medical, 2023
What is Occlusion Myocardial Infarction (OMI)?

https://www.powerfulmedical.com/blog/what-is-occlusion-myocardial-infarction-omi/


Meyers, Smith et al — Ann Emerg Med 74(4) — S26, 2019
What is the Prevalence of STEMI-OMI ????

https://www.annemergmed.com/article/S0196-0644(19)30744-9/fulltext

Study Objectives
The goal of the STEMI vs. NSTEMI paradigm was to identify those with Occlusion MI (OMI) who benefit from emergent reperfusion. However, STEMI criteria have poor sensitivity and specificity for OMI. We sought to evaluate the prevalence and ratios of STEMI(+) vs. STEMI(-) OMIs among a group of consecutive ED patients with suspected acute coronary syndrome (ACS).

Methods
We performed a retrospective, observational, case-control study at a large, academic, suburban ED. We performed a case-control study by combining patients from 1) a consecutive cohort of ED patients with suspected ACS over a 4-month period who were admitted and/or underwent catheterization, and 2) an additional group of OMI cases from our catheterization lab activation database. Main outcomes were presence of acute coronary Occlusion MI, presence of STEMI criteria, door-to-balloon times, etc. Descriptive statistics were used to summarize findings.

Results
During the study period 367 patients met the above inclusion criteria. 36% were female, average age was 65 years, 86% were Caucasian, and 56% had prior history of CAD. Of these 367, 117 patients (32%) underwent emergent cardiology consultation for emergent cath (“STEMI activation”) with median door-to-cath lab time 38 minutes, while the rest were admitted for further ACS workup including possible catheterization with median door-to-cath time of 1294 minutes.
127 (35%) patients had Occlusion MI, of which 55 (43%) met STEMI criteria and 72 (57%) did not. Median (IQR) times from door-to-cath lab for the STEMI(+) OMI vs. the STEMI(-) OMI groups were 30 (18-56) vs 100 (46-953) minutes. Catheterization was performed within 90 minutes of arrival in 85% of STEMI(+) OMI, but only 46% of STEMI(-) OMI. Average peak troponin T in the STEMI(+) OMI (N=55), STEMI(-) OMI (N=72), and No Occlusion (N=240) groups were 5.90, 6.24, and 0.14 ng/mL, whereas the median peak troponins were 4.09, 3.28, and 0.00, respectively. The difference in peak troponin between STEMI(+) OMI and STEMI(-) OMI groups was not statistically significant (p=0.85), while the difference between each group vs. the No Occlusion group was significant (p<0.001 for both).

Conclusion
In this case-control study of ED ACS patients who warranted admission and/or emergent consultation for catheterization, 57% of Occlusion MIs did not present with STEMI criteria on ECG. These STEMI(-) OMIs had significant delays to the cath lab but similar peak troponin levels compared to the STEMI(+) OMI group. These data support the growing notion that STEMI(-) OMI is an underserved, under-identified, yet important subgroup of ACS patients.



Dzurikova — Powerful Medical, 2024
STEMI Equivalents: Navigating Hidden Indicators of Acute Coronary Occlusion

https://www.powerfulmedical.com/blog/stemi-equivalents/

In the critical landscape of cardiac emergency care, early detection and accurate diagnosis of myocardial infarction (MI) are paramount for enhancing patient survival and outcomes1. The established criteria for diagnosing an ST-segment elevation myocardial infarction (STEMI) have been foundational in guiding healthcare professionals in emergency cardiovascular care for several decades2

The criteria require the observation of the ST-segment elevation at the J point in two contiguous leads, requiring the elevation to measure at least 2 mm (0.2 mV) in men under 40 years of age, 2.5 mm (0.25 mV) in men aged 40 years and older, or 1.5 mm (0.15 mV) in women in leads V2–V3, and/or at least 1 mm (0.1 mV) in other contiguous chest leads or the limb leads 3

REF #3 — Amsterdam EA, et al. 2014 AHA/ACC Guideline for the Management of Patients With Non–ST-Elevation Acute Coronary Syndromes. J Am Coll Cardiol. 2014;64(24):e139-e228.

What is Occlusion Myocardial Infarction (OMI)
Occlusion Myocardial Infarction (OMI) refers to an acute coronary occlusion or near occlusion of a culprit artery with insufficient collateral circulation, resulting in transmural myocardial infarction and cardiac tissue death.

ACO = Acute Coronary Occlusion = an OMI



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Observational studies indeed show that the current STEMI criteria miss approximately one third of ACOs.[13 21] This suggests that, when STEMI criteria are not met, the physicians do not manage to identify the patients with ACO among all patients with undifferentiated persistent chest pain

REF #21 — Meyers, Smith et al — Accuracy of OMI ECG findings versus STEMI criteria for diagnosis of acute coronary occlusion myocardial infarction. Int J Cardiol Heart Vasc 2021;33:100767.

https://pubmed.ncbi.nlm.nih.gov/33912650/


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JESSEM DRAFT (7/6/2024):

  Written by Jesse McLaren

 

A previously healthy 60 year old developed exertional chest pain with diaphoresis, and called EMS. Here’s the EMS ECG, digitized with PM cardio. What do you think?





 

 

 

 

There’s sinus arrhythmia with normal conduction, normal axis and normal voltages. There’s loss of R waves in V2-3 with hyperacute waves V1-5. There’s no significant ST elevation but there are two forms of ST depression: deWinter T wave V3-5 and precordial swirl with ST depression V6 reciprocal to subtle STE in V1. In the limb leads there’s no ST elevation, but there are hyperacute T waves in I/aVL with reciprocal inferior ST depression. So while there’s no diagnostic STEMI criteria, there are multiple ischemic abnormalities in 11/12 leads involving QRS, ST and T waves, which are diagnostic of a proximal LAD occlusion. 

 

Queen of Hearts was highly confident in OMI based on the hyperacute T waves and ST depression, despite absence of STEMI criteria:



The paramedics called a code STEMI from the field, and gave the patient aspirin and three sprays of nitro. They arrived in the ED 30 minutes later to meet the cardiology team, where an ECG was repeated:
 

 

Again no STEMI criteria, and there has been improvement in the deWinter and swirl pattern. But there are ongoing precordial hyperacute T waves and ongoing inferior ST depression, and this is reciprocal to subtle straight ST elevation in aVL. The final blinded cardiology interpretation noted only the minimal inferior ST depression, but the ECG is still diagnostic of proximal LAD occlusion.

 

Fortunately the treating cardiology team noted the hyperacute T waves and subtle STE in aVL and continued with the plan for emergent angiography: 100% proximal LAD occlusion. First trop was 7,000ng/L (normal <26 in males in <16 in females) which goes along with the loss of R waves, and peak was 94,000 ng/L. Echo showed EF reduced to 35% with anteroseptal hypokinesis and akinetic apex. Discharge ECG showed antero-lateral reperfusion T wave inversion:



The discharge diagnosis was ‘STEMI’ but no ECG met STEMI criteria, and blinded cardiology interpretation of the ED ECG was also STEMI negative. In the current paradigm it would make more sense to call this Non-STEMI because the patient had a type 1 MI without any ECG meeting STEMI criteria. But that wouldn’t account for why the cath lab was activated, because this is supposed to be reserved for patients with STEMI.  So the discharge diagnosis ‘STEMI’ was more a reflection of the time to treatment (emergent cath) rather than current diagnostic dichotomy (STEMI vs Non-STEMI). But this was STEMI negative despite having an Occlusion MI, or STEMI(-)OMI, and received rapid reperfusion despite the current paradigm. 

 

Discharge diagnosis: STEMI/NSTEMI vs OMI/NOMI

 

Why this matters is that greater than 25% of ‘Non-STEMI’ patients with delayed angiography have the exact same pathology of acute coronary occlusion. Their discharge diagnosis also better reflects time to treatment (non-urgent cath), rather than diagnosis. This creates a bias in STEMI/Non-STEMI databases: not only are STEMI(-)OMI with delayed reperfusion buried in Non-STEMI databases along with non-occlusive MIs, which prevents us learning from missed occlusions; but also, STEMI(-)OMI that are rapidly reperfused are buried in STEMI databases, which prevents us from learning from great cases like this. Both reinforce the false STEMI/non-STEMI dichotomy, and are barriers to shifting towards the OMI paradigm.

 

For comparison, see this similar case of a 60 year old with chest pain, with cath lab activated from the field:

 

 

Also diagnostic of LAD occlusion, with anterior hyperacute T waves, precordial swirl, and subtle inferior ST depression. The patient also had a 100% proximal LAD occlusion, with a peak troponin of 100,000 ng/L. But because Code STEMI was cancelled on arrival and the patient had delayed angiography, the discharge diagnosis was 'non-STEMI' despite having the exact same pathology. Rather than calling the first 'STEMI' because of rapid reperfusion and the second 'non-STEMI' because of delayed reperfusion, both should be called what they are: OMI - and then we can learn from both.

 

The new ACC expert consensus explains that: “STEMI ECG criteria on a standard 12-lead ECG alone will miss a significant minority of patients who have acute coronary occlusion. Therefore, the ECG should be closely examined for subtle changes that may represent initial ECG signs of vessel occlusion, such as hyperacute T waves or ST-segment elevation <1 mm, particularly when combined with reciprocal ST-segment depression.” But if STEMI criteria is a poor surrogate marker, and if what we care about is acute coronary occlusion, then discharge diagnoses should change to reflect a new classification of OMI/NOMI rather than STEMI/Non-STEMI.

 

Take home

1. STEMI criteria has poor sensitivity for acute coronary occlusion

2. Other signs of occlusion include hyperacute T waves, deWinter pattern, precordial swirl, and ST depression reciprocal to subtle ST elevation/hyperacute T 

3. Discharge diagnoses and MI classification should reflect patient outcomes of Occlusion vs non-Occlusion MI, not arbitrary STE vs Non-STE criteria, or rapid vs delayed time to cath. All OMIs can then be reviewed to identify which were missed and which were rapidly reperfused, in order to learn from both

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