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Emergency Medicine

Acute Myocardial Infarction or Not?

Educational Objective
To identify the key insights or developments described in this article

1 Credit CME

JAMA Internal Medicine

Published Online: April 18, 2022

Challenges in Clinical Electrocardiography

Article Information and Disclosures

Chuan-Hai Zhang, MD¹;

Ting-Ting Li, MD¹;

Xiaohong Chen, MD²

Author Affiliations

¹Department of Cardiology, The First Affiliated Hospital of Jinzhou Medical University, Jinzhou, Liaoning, China
²Department of Emergency, The Third People’s Hospital of Chengdu, The Affiliated Hospital of Southwest Jiaotong University, Chengdu, Sichuan, China

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A patient in their 70s presented to the emergency department with acute chest pain that had lasted 3 hours. The patient had no history of chronic disease or acute infection and denied any tobacco, alcohol, or illicit drug use. During a routine physical examination 1 month prior, no abnormality was found on the patient’s electrocardiogram (ECG). At admission, blood pressure and pulse rate were 157/93 mm Hg and 63 beats/min, respectively. The troponin I level was 0.1394 ng/mL (normal range: 0-0.0342 ng/mL; to convert to μg/L, multiply by 1.0), and brain-type natriuretic peptide level was 213.60 pg/mL (normal range: 0-100 pg/mL; to convert to ng/L, multiply by 1.0). The admission ECG was obtained at our hospital (Figure, A). A repeated ECG was obtained after 1 hour (Figure, B).

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Timely and accurate identification of acute coronary occlusion in the setting of ischemic symptoms is critical to initiating urgent angiography and appropriate reperfusion therapy. The presence of LBBB on the ECG can conceal the changes of AMI. Therefore, the ECG diagnosis of AMI in patients with LBBB is often challenging. On one hand, most patients referred for primary percutaneous coronary intervention because of the presence of LBBB are not experiencing an AMI.¹ On the other hand, patients with LBBB and AMI are usually at high risk of fatality and often experience delays in reperfusion therapy that may lead to critical consequences.² To solve this problem, several ECG criteria have been proposed to diagnose AMI in the presence of LBBB.

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Article Information

Corresponding Author: Xiaohong Chen, MD, Department of Emergency, The Third People’s Hospital of Chengdu, The Affiliated Hospital of Southwest Jiaotong University, Chengdu 610000, Sichuan, China (xiaohong_fly@163.com).

Published Online: April 18, 2022. doi:10.1001/jamainternmed.2022.0519

Conflict of Interest Disclosures: None reported.

References

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Di Marco A , Anguera I , Rodríguez M , et al. Assessment of Smith algorithms for the diagnosis of acute myocardial infarction in the presence of left bundle branch block. Rev Esp Cardiol (Engl Ed). 2017;70(7):559-566. doi:10.1016/j.recesp.2016.11.010 PubMed Google Scholar Crossref

Di Marco A , Rodriguez M , Cinca J , et al. New electrocardiographic algorithm for the diagnosis of acute myocardial infarction in patients with left bundle branch block. J Am Heart Assoc. 2020;9(14):e015573. doi:10.1161/JAHA.119.015573 PubMed Google Scholar Crossref

AMA CME Accreditation Information

Credit Designation Statement: The American Medical Association designates this Journal-based CME activity activity for a maximum of 1.00  AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Successful completion of this CME activity, which includes participation in the evaluation component, enables the participant to earn up to:

1.00 Medical Knowledge MOC points in the American Board of Internal Medicine's (ABIM) Maintenance of Certification (MOC) program;;
1.00 Self-Assessment points in the American Board of Otolaryngology – Head and Neck Surgery’s (ABOHNS) Continuing Certification program;
1.00 MOC points in the American Board of Pediatrics’ (ABP) Maintenance of Certification (MOC) program;
1.00 Lifelong Learning points in the American Board of Pathology’s (ABPath) Continuing Certification program; and
1.00 CME points in the American Board of Surgery’s (ABS) Continuing Certification program

It is the CME activity provider's responsibility to submit participant completion information to ACCME for the purpose of granting MOC credit.