[Skip to Content]
[Skip to Content Landing]

The Imposter Dance of Alternating QRS Complexes

To identify the key insights or developments described in this article
1 Credit CME

A patient in their late 50s presented to the emergency department for acute onset chest pain with diaphoresis. The patient reported having had chest tightness followed by mild dyspnea after rushing down a set of stairs 2 days prior. The pain had gradually subsided after resting. In addition, on the evening of admission, just after finishing a meal, the patient experienced a fairly sudden onset of severe nonradiating pressure-like pain in the central portion of the chest accompanied by cold sweating; the pain persisted and progressed. Self-reported medical history included smoking 1 pack of cigarettes daily for more than 3 decades and taking medications for type 2 diabetes and hypertension.

Please finish quiz first before checking answer.

You answered correctly!

Read the answer below and download your certificate.

You answered incorrectly.

Read the discussion below and retake the quiz.

An ECG with alternating QRS complex morphologic findings has numerous potential causes and invokes an electrocardiographic differential diagnosis including but not limited to ventricular bigeminy, electrical alternans, atrial bigeminy with aberrant conduction, bidirectional ventricular tachycardia, sinus rhythm with alternating bundle-branch block, and WPW alternans. Electrical alternans are classically associated with substantial pericardial effusion with or without cardiac tamponade. True electrical alternans should draw early and aggressive investigation and correlation with the physical examination findings. In this case, alternating QRS complexes of differing amplitude were observed but the width of the QRS complexes and the PR intervals varied from beat to beat, which would not be expected with electrical alternans.

Survey Complete!

Sign in to take quiz and track your certificates

Buy This Activity

JN Learning™ is the home for CME and MOC from the JAMA Network. Search by specialty or US state and earn AMA PRA Category 1 Credit(s)™ from articles, audio, Clinical Challenges and more. Learn more about CME/MOC

CME Disclosure Statement: Unless noted, all individuals in control of content reported no relevant financial relationships. If applicable, all relevant financial relationships have been mitigated.

Article Information

Corresponding Author: Po-Chih Lin, MD, Cardiovascular Center, Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital, No. 7 Zhongshan S Rd, Zhongzheng, Taipei 100, Taiwan (juipeter@gmail.com).

Published Online: September 26, 2022. doi:10.1001/jamainternmed.2022.3965

Conflict of Interest Disclosures: None reported.

References
1.
Hindman  MC , Last  JH , Rosen  KM .  Wolff-Parkinson-White syndrome observed by portable monitoring.   Ann Intern Med. 1973;79(5):654-663. doi:10.7326/0003-4819-79-5-654PubMedGoogle ScholarCrossref
2.
Kinoshita  S , Katoh  T .  Alternans Wolff-Parkinson-White syndrome: supernormal conduction as an alternative mechanism.   J Electrocardiol. 2007;40(5):448-449. doi:10.1016/j.jelectrocard.2007.01.004PubMedGoogle ScholarCrossref
3.
Ortega-Carnicer  J , Benezet-Peñaranda  J .  Bradycardia-dependent block in the accessory pathway in a patient with alternans Wolff-Parkinson-White syndrome.   J Electrocardiol. 2006;39(4):419-420. doi:10.1016/j.jelectrocard.2006.02.013PubMedGoogle ScholarCrossref
Close
Want full access to the AMA Ed Hub?
After you sign up for AMA Membership, make sure you sign in or create a Physician account with the AMA in order to access all learning activities on the AMA Ed Hub
Buy this activity
Close
Want full access to the AMA Ed Hub?
After you sign up for AMA Membership, make sure you sign in or create a Physician account with the AMA in order to access all learning activities on the AMA Ed Hub
Buy this activity
Close
With a personal account, you can:
  • Access free activities and track your credits
  • Personalize content alerts
  • Customize your interests
  • Fully personalize your learning experience
Education Center Collection Sign In Modal Right
Close

Name Your Search

Save Search
With a personal account, you can:
  • Access free activities and track your credits
  • Personalize content alerts
  • Customize your interests
  • Fully personalize your learning experience
Close
Close

Lookup An Activity

or

My Saved Searches

You currently have no searches saved.

Close

My Saved Courses

You currently have no courses saved.

Close