[Skip to Content]
[Skip to Content Landing]

Noteworthy P Waves in an Elderly Woman

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

A patient in their 70s was referred to the emergency department for worsening shortness of breath, chest tightness, and episodes of palpitations. The patient’s medical history was remarkable for hypertension and kidney insufficiency. Initial evaluation revealed a heart rate of 53 beats/min, blood pressure of 221/85 mm Hg. Laboratory test results revealed that the patient’s B-type natriuretic peptide level was 838.6 pg/mL (normal level, <300 pg/mL). The initial 12-lead electrocardiogram (ECG) is presented in the Figure, A. Transthoracic echocardiography showed left atrial enlargement (52 mm), normal left ventricular wall thickness, and mild pulmonary 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.

Compared with the QRS complex, the P wave is small, and it is difficult to find abnormalities on the surface electrocardiogram. The normal P wave duration is shorter than 120 milliseconds.3 In the present case, the noteworthy findings on the patient’s initial ECG is prolonged P-wave duration (180 milliseconds) with biphasic morphology in the inferior leads. The P-wave represents normal depolarization that occurs from the right atrium to the left atrium through the Bachmann bundle or region. Bachmann bundle is a muscular bundle composed of aligned myocardial fibers in parallel. Any delay in atrial conduction is pathologically considered as IAB.3 Similarly to atrioventricular block, IAB can be divided into varying degrees of block. The findings shown in the Figure (panel A) may be considered as advanced IAB, which was first described in 1956.2 It is a featured of P-wave duration longer than 120 milliseconds with biphasic P-wave morphology in the inferior limb leads (II, III, and aVF).3 The electrophysiologic mechanism underlying advanced IAB has been explained—the depolarization was completely blocked in the Bachmann region, and activation of the left atrium occurs retrogradely through a zone located close to the coronary sinus, leading to the presence of delay of left atrial depolarization, and forming superior and left deviation of the terminal vector of the P wave. This can explain P-wave prolongation and final negative component of the P wave in the inferior leads, which is different from left atrial enlargement. Cardiac morphological examination (eg, cardiac echocardiography) has confirmed that it may be usually associated with left atrial enlargement, as demonstrated in the present case. At this time, the superior and left deviation of the terminal vector of the P wave generated by IAB can affect the classic V1 pattern of left atrial enlargement, making the negative amplitude of P wave in lead V1 unremarkable (in this case). Therefore, left atrial enlargement cannot be excluded according to the absence of classic V1 pattern. Atrial fibrosis is considered the anatomic substrate of advanced IAB.1,4 Over time the architecture of fibrotic myocardial tissue becomes heterogeneous, thereby affecting intercellular conduction, increasing anisotropy, and contributing to conduction slowing; this development of functional and structural block creates an arrhythmogenic substrate.3,57 The harm of atrial fibrillation has been recognized by clinicians, and several P-wave parameters including P-wave duration, advanced IAB, abnormal P-wave terminal force in V1, low P-wave amplitude in lead I, and abnormal P-wave axis have been associated with increased risk of atrial fibrillation.8 Advanced IAB was found to be independently associated with an increased risk of atrial fibrillation in the ARIC study9 and in the Copenhagen ECG Study.10 Patients older than 60 years with advanced IAB have a 50% risk for developing atrial fibrillation at 6 years; meanwhile, the risk for atrial fibrillation is only 10% among patients who do not have underlying advanced IAB.3 The clinical entity characterized by the association of advanced IAB with atrial fibrillation and other atrial arrhythmias has been named Bayés syndrome.2 An increasing number of cases have demonstrated a link between IAB and the development of left atrial appendage thrombus and embolic stroke in sinus rhythm.3 This patient also finally developed a stroke event 1.5 years later. The clinical treatment of IAB is a hot topic, and the antiarrhythmic medications, cardiovascular risk factor modification, and anticoagulation may be the important investigative treatment modalities.3

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: Renguang Liu, The Cardiovascular Institute of the First Affiliated Hospital of Jinzhou Medical University, Renmin Street, Jinzhou 121000, Liaoning Province, China (liurenguanglaoshi@126.com).

Published Online: November 21, 2022. doi:10.1001/jamainternmed.2022.4813

Conflict of Interest Disclosures: None reported.

Baranchuk  A , Torner  P , de Luna  AB .  Bayés syndrome: what is it?   Circulation. 2018;137(2):200-202. doi:10.1161/CIRCULATIONAHA.117.032333PubMedGoogle ScholarCrossref
Bacharova  L , Wagner  GS .  The time for naming the interatrial block syndrome: Bayes syndrome.   J Electrocardiol. 2015;48(2):133-134. doi:10.1016/j.jelectrocard.2014.12.022PubMedGoogle ScholarCrossref
Power  DA , Lampert  J , Camaj  A ,  et al.  Cardiovascular Complications of interatrial conduction block: JACC state-of-the-art review.   J Am Coll Cardiol. 2022;79(12):1199-1211. doi:10.1016/j.jacc.2022.01.030PubMedGoogle ScholarCrossref
Bayés de Luna  A , Platonov  P , Cosio  FG ,  et al.  Interatrial blocks. a separate entity from left atrial enlargement: a consensus report.   J Electrocardiol. 2012;45(5):445-451. doi:10.1016/j.jelectrocard.2012.06.029PubMedGoogle ScholarCrossref
Platonov  PG .  Atrial fibrosis: an obligatory component of arrhythmia mechanisms in atrial fibrillation?   J Geriatr Cardiol. 2017;14(4):233-237. doi:10.11909/j.issn.1671-5411.2017.04.008PubMedGoogle Scholar
Schotten  U , Verheule  S , Kirchhof  P , Goette  A .  Pathophysiological mechanisms of atrial fibrillation: a translational appraisal.   Physiol Rev. 2011;91(1):265-325. doi:10.1152/physrev.00031.2009PubMedGoogle ScholarCrossref
Zhao  J , Butters  TD , Zhang  H ,  et al.  An image-based model of atrial muscular architecture: effects of structural anisotropy on electrical activation.   Circ Arrhythm Electrophysiol. 2012;5(2):361-370. doi:10.1161/CIRCEP.111.967950PubMedGoogle ScholarCrossref
Chen  LY , Ribeiro  ALP , Platonov  PG ,  et al.  P Wave parameters and indices: a critical appraisal of clinical utility, challenges, and future research-a consensus document endorsed by the International Society of Electrocardiology and the International Society for Holter and Noninvasive Electrocardiology.   Circ Arrhythm Electrophysiol. 2022;15(4):e010435. doi:10.1161/CIRCEP.121.010435PubMedGoogle Scholar
O’Neal  WT , Zhang  ZM , Loehr  LR , Chen  LY , Alonso  A , Soliman  EZ .  Electrocardiographic advanced interatrial block and atrial fibrillation risk in the general population.   Am J Cardiol. 2016;117(11):1755-1759. doi:10.1016/j.amjcard.2016.03.013PubMedGoogle ScholarCrossref
Skov  MW , Ghouse  J , Kühl  JT ,  et al.  Risk prediction of atrial fibrillation based on electrocardiographic interatrial block.   J Am Heart Assoc. 2018;7(11):e008247. doi:10.1161/JAHA.117.008247PubMedGoogle ScholarCrossref
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 credit toward the CME [and Self-Assessment requirements] of the American Board of Surgery’s Continuous Certification program

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

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
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
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

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

Lookup An Activity


My Saved Searches

You currently have no searches saved.


My Saved Courses

You currently have no courses saved.