Why do we keep missing left circumflex artery myocardial infarctions?

BACKGROUND

Diagnosis of left circumflex artery (LCx) myocardial infarctions via 12‑lead electrocardiogram (ECG) has posed a challenge to healthcare professionals for many years.

METHODS AND RESULTS

A retrospective observational study was performed to analyze patients admitted with myocardial infarction. The study used electronic medical records and specific ICD-10 codes to identify eligible patients, resulting in 2032 encounters. After independent adjudication of cardiac biomarkers, coronary angiography, and electrocardiographic changes, a final patient population of 58 encounters with acute occlusion myocardial infarction (OMI) with a culprit LCx lesion was established. OMI was defined as a lesion with either thrombolysis in myocardial infarction flow (TIMI) 0-2 or TIMI 3 with Troponin I > 1 ng/mL (Reference range 0.00-0.03 ng/mL). ECGs of these patients were then independently evaluated and grouped into 8 different classifications based on the presence or absence of ST elevation and/or depression in corresponding leads. ECG patterns and anatomical characteristics (proximal or distal to the first obtuse marginal artery) of the LCx lesions were then correlated. The appropriateness of triage and delay in reperfusion therapy were also assessed. Those with a left dominant or codominant circulation, and with LCx lesions proximal to the first obtuse marginal artery, were more likely to present with no or subtle ST-segment changes that led to delays in reperfusion therapy.

CONCLUSIONS

Patients with left or codominant coronary artery circulation, with OMI proximal to the first obtuse marginal artery, may be less likely to have "classic" findings of ST-segment elevation on ECG due to cancellation forces in the limb leads.

International evaluation of an artificial intelligence-powered electrocardiogram model detecting acute coronary occlusion myocardial infarction

Aims

A majority of acute coronary syndromes (ACS) present without typical ST elevation. One-third of non-ST-elevation myocardial infarction (NSTEMI) patients have an acutely occluded culprit coronary artery [occlusion myocardial infarction (OMI)], leading to poor outcomes due to delayed identification and invasive management. In this study, we sought to develop a versatile artificial intelligence (AI) model detecting acute OMI on single-standard 12-lead electrocardiograms (ECGs) and compare its performance with existing state-of-the-art diagnostic criteria.

Methods and results

An AI model was developed using 18 616 ECGs from 10 543 patients with suspected ACS from an international database with clinically validated outcomes. The model was evaluated in an international cohort and compared with STEMI criteria and ECG experts in detecting OMI. The primary outcome of OMI was an acutely occluded or flow-limiting culprit artery requiring emergent revascularization. In the overall test set of 3254 ECGs from 2222 patients (age 62 ± 14 years, 67% males, 21.6% OMI), the AI model achieved an area under the curve of 0.938 [95% confidence interval (CI): 0.924-0.951] in identifying the primary OMI outcome, with superior performance [accuracy 90.9% (95% CI: 89.7-92.0), sensitivity 80.6% (95% CI: 76.8-84.0), and specificity 93.7 (95% CI: 92.6-94.8)] compared with STEMI criteria [accuracy 83.6% (95% CI: 82.1-85.1), sensitivity 32.5% (95% CI: 28.4-36.6), and specificity 97.7% (95% CI: 97.0-98.3)] and with similar performance compared with ECG experts [accuracy 90.8% (95% CI: 89.5-91.9), sensitivity 73.0% (95% CI: 68.7-77.0), and specificity 95.7% (95% CI: 94.7-96.6)].

Conclusion

The present novel ECG AI model demonstrates superior accuracy to detect acute OMI when compared with STEMI criteria. This suggests its potential to improve ACS triage, ensuring appropriate and timely referral for immediate revascularization.

Missing occlusions: Quality gaps for ED patients with occlusion MI

BACKGROUND

ST-elevation Myocardial Infarction (STEMI) guidelines encourage monitoring of false positives (Code STEMI without culprit) but ignore false negatives (non-STEMI with occlusion myocardial infarction [OMI]). We evaluated the hospital course of emergency department (ED) patients with acute coronary syndrome (ACS) using STEMI vs OMI paradigms.

METHODS

This retrospective chart review examined all ACS patients admitted through two academic EDs, from June 2021 to May 2022, categorized as 1) OMI (acute culprit lesion with TIMI 0-2 flow, or acute culprit lesion with TIMI 3 flow and peak troponin I >10,000 ng/L; or, if no angiogram, peak troponin >10,000 ng/L with new regional wall motion abnormality), 2) NOMI (Non-OMI, i.e. MI without OMI) or 3) MIRO (MI ruled out: no troponin elevation). Patients were stratified by admission for STEMI. Initial ECGs were reviewed for automated interpretation of "STEMI", and admission/discharge diagnoses were compared.

RESULTS

Among 382 patients, there were 141 OMIs, 181 NOMIs, and 60 MIROs. Only 40.4% of OMIs were admitted as STEMI: 60.0% had "STEMI" on ECG, and median door-to-cath time was 103 min (IQR 71-149). But 59.6% of OMIs were not admitted as STEMI: 1.3% had "STEMI" on ECG (p < 0.001) and median door-to-cath time was 1712 min (IQR 1043-3960; p < 0.001). While 13.9% of STEMIs were false positive and had a different discharge diagnosis, 32.0% of Non-STEMIs had OMI but were still discharged as "Non-STEMI."

CONCLUSIONS

STEMI criteria miss a majority of OMI, and discharge diagnoses highlight false positive STEMI but never false negative STEMI. The OMI paradigm reveals quality gaps and opportunities for improvement.

Diagnosis of Occlusion Myocardial Infarction in Patients with Left Bundle Branch Block and Paced Rhythms

PURPOSE OF REVIEW

A number of criteria have been developed to aid with the diagnosis of occlusion myocardial infarction (OMI) in patients with left bundle branch block (LBBB) and ventricular paced rhythms (VPR). The current guidelines do not provide clear preference for any specific ECG criteria in LBBB and paced rhythm patients.

RECENT FINDINGS

This review delineates the difficulties of electrocardiographic diagnosis of OMI in both LBBB and VPR patients. We describe the original Sgarbossa and the newer criteria and their diagnostic performances. We highlight the expected changes of newer pacing modalities and how they may interfere with the electrocardiographic diagnosis of OMI. We recommend utilizing the Cai et al. algorithm, which combines clinical assessment with the Smith Modified Sgarbossa ECG criteria, for both LBBB and right ventricular pacing patients with suspected OMI. There is limited data concerning ECG changes of OMI in patients with the newer pacing modalities, such as biventricular, His-bundle, or left bundle branch pacing.

Accuracy of OMI ECG findings versus STEMI criteria for diagnosis of acute coronary occlusion myocardial infarction

OBJECTIVE

In the STEMI paradigm of Acute Myocardial Infarction (AMI), many NSTEMI patients have unrecognized acute coronary occlusion MI (OMI), may not receive emergent reperfusion, and have higher mortality than NSTEMI patients without occlusion. We have proposed a new OMI vs. Non-Occlusion MI (NOMI) paradigm shift. We sought to compare the diagnostic accuracy of OMI ECG findings vs. formal STEMI criteria for the diagnosis of OMI. We hypothesized that blinded interpretation for predefined OMI ECG findings would be more accurate than STEMI criteria for the diagnosis of OMI.

METHODS

We performed a retrospective case-control study of patients with suspected acute coronary syndrome. The primary definition of OMI was either 1) acute TIMI 0-2 flow culprit or 2) TIMI 3 flow culprit with peak troponin T ≥ 1.0 ng/mL or I ≥ 10.0 ng/mL.

RESULTS

808 patients were included, of whom 49% had AMI (33% OMI; 16% NOMI). Sensitivity, specificity, and accuracy of STEMI criteria vs Interpreter 1 using OMI ECG findings among 808 patients were 41% vs 86%, 94% vs 91%, and 77% vs 89%, and for Interpreter 2 among 250 patients were 36% vs 80%, 91% vs 92%, and 76% vs 89%. STEMI(-) OMI patients had similar infarct size and mortality as STEMI(+) OMI patients, but greater delays to angiography.

CONCLUSIONS

Blinded interpretation using predefined OMI ECG findings was superior to STEMI criteria for the ECG diagnosis of Occlusion MI. These data support further investigation into the OMI vs. NOMI paradigm and suggest that STEMI(-) OMI patients could be identified rapidly and noninvasively for emergent reperfusion using more accurate ECG interpretation.

Post-arrest wide complex rhythm: What is the cause of death?

A 72-year-old man presented to the ED following witnessed cardiac arrest. After return of spontaneous circulation, an ECG was performed which demonstrated a wide complex rhythm with "shark fin" morphology. With careful examination it is possible to identify the J point and determine that the electrocardiogram (ECG) findings actually represent massive ST-elevation indicative of occlusion myocardial infarction (OMI). Initial troponin was undetectable. The patient underwent emergent cardiac catheterization and had a 100% proximal LAD occlusion that was successfully stented. The patient was discharged home neurologically intact several days later. This case highlights the importance of careful ECG interpretation and the limitations of troponin assays in the evaluation of acute coronary syndrome. Most importantly, we demonstrate how to evaluate for ST elevation in the context of a widened QRS complex.