The End of "Left Atrial Overload"Reply

Keywords
Heart Atria; Electrocardiography; Diagnosis

Palavras-chave
Átrios do Coração; Eletrocardiografia; Diagnóstico

Keywords
Heart Atria; Electrocardiography; Diagnosis

Palavras-chave
Átrios do Coração; Eletrocardiografia; Diagnóstico

To the Editor,

We read with great interest the article by Oliveira et al.¹ The authors are to be commended for conducting a study of this magnitude and rigor. While previous literature relied on smaller sample sizes or non-standard/obsolete echocardiographic cutoffs for left atrial enlargement (LAE),²–⁵ the ELSA-Brasil cohort provides the statistical power necessary to settle a longstanding debate in clinical cardiology. We believe this research is destined to become a reference point in standard electrocardiography textbooks.

We would also like to expand upon a critical terminological and conceptual precision issue prevalent in Brazilian literature: the persistent use of the term "Sobrecarga Atrial Esquerda" (Left Atrial Overload) to describe electrocardiographic findings. We believe that it is imperative for the cardiology community to be aware of the difference between "enlargement" (a structural change) and "overload" (a hemodynamic state). As noted by Alpert et al., electrocardiographic criteria often mistakenly conflate these distinct pathophysiological entities.⁶ The authors of the current study correctly utilized left atrial volume index (LAVI) via echocardiography as the gold standard, which measures enlargement (dilatation), not overload (pressure or volume load). "Overload" implies a hemodynamic mechanism that the electrocardiogram (ECG) cannot directly measure, and the echocardiogram assesses it only through surrogates. Consequently, the term "Overload" is scientifically imprecise in this context and should be retired from the lexicon in favor of terms that accurately describe the observed phenomenon.

If a P-wave ≥ 120 ms does not reliably predict LAE, let alone "overload", what does it represent? The answer lies in the concept of interatrial block (IAB). While Josephson et al. correctly identified that "LAE" patterns on ECG often represented conduction delays independent of atrial size.⁷ It was the pioneering work of Bayés de Luna that transformed this observation into a distinct clinical entity. Beginning in 1979, he systematically described and classified these conduction disorders, establishing that IAB could occur transiently and, crucially, in the absence of structural enlargement.⁸

Bayés de Luna moved beyond the mere observation of electromechanical dissociation to establish the clinical significance of the finding. He classified IAB into partial and advanced forms—the former defined by a P-wave ≥ 120 ms with normal sinus morphology, while the latter also includes biphasic (±) morphology in inferior leads—and identified its pathological substrate: fibrotic atrial cardiomyopathy.⁹ This decades-long research culminated in the recognition of "Bayés Syndrome", identifying Advanced IAB as a key predictor of supraventricular arrhythmias.¹⁰

Therefore, a P-wave duration ≥ 120 ms should not be viewed as a "false positive" for enlargement, but rather as a "true positive" for IAB, specifically a conduction delay at the Bachmann region (Figure 1). A 120 ms threshold is the optimal diagnostic criterion for this condition.¹¹

Figure 1
While a P-wave ≥ 120 ms is traditionally termed "Left Atrial Overload" (Sobrecarga) or "Enlargement," evidence from the ELSA-Brasil cohort (Oliveira et al.) demonstrates a poor correlation with actual structural enlargement assessed by echocardiography. Conversely, the electrical finding represents a conduction delay at the Bachmann region. Therefore, the nomenclature should shift from anatomical or hemodynamic assumptions ("Enlargement/Overload") to the precise electrophysiological definition: Interatrial Block.

This distinction carries profound prognostic weight. IAB is an independent entity associated with atrial fibrosis and electromechanical remodeling.¹² Furthermore, population-based studies like the ARIC study¹³ have shown that these conduction defects are independent predictors of atrial fibrillation (AF). Similar to AF, this electrical marker is strongly associated with stroke.¹⁴

We should abandon the term "Sobrecarga" (Overload) because it implies a hemodynamic burden that is neither directly measured by the ECG nor synonymous with the structural dimensions assessed by the gold standard (LAVI). Furthermore, given the poor accuracy demonstrated in this study, we should also abandon the term "Enlargement" for a prolonged P-wave. Instead, Oliveira's research is a prime opportunity to endorse a clear distinction - label a P-wave ≥ 120 ms as what it truly is: Interatrial Block.¹⁵ This terminological shift will ensure scientific accuracy and enhance risk stratification for the arrhythmias and embolic events associated with atrial cardiomyopathy.

References

• ¹ Oliveira ACS, Carvalho VT, Pinto-Filho MM, Brant LC, Barreto SM, Foppa M, et al. Diagnostic Utility of P-Wave Duration in Identifying Left Atrial Enlargement: Insights from the ELSA-Brasil Cohort. Arq Bras Cardiol. 2025;122(10):e20250151. doi: 10.36660/abc.20250151.
  » https://doi.org/10.36660/abc.20250151
• ² Aiwuyo HO, Osarenkhoe JO, Umuerri EM, Aigbe FI, Obasohan A. Association between Electrocardiographic Left Atrial Enlargement and Echocardiographic Left Atrial Indices among Hypertensive Subjects in a Tertiary Hospital in South South Nigeria. Cureus. 2023;15(1):e34330. doi: 10.7759/cureus.34330.
  » https://doi.org/10.7759/cureus.34330
• ³ Lee KS, Appleton CP, Lester SJ, Adam TJ, Hurst RT, Moreno CA, et al. Relation of Electrocardiographic Criteria for Left Atrial Enlargement to Two-Dimensional Echocardiographic Left Atrial Volume Measurements. Am J Cardiol. 2007;99(1):113-8. doi: 10.1016/j.amjcard.2006.07.073.
  » https://doi.org/10.1016/j.amjcard.2006.07.073
• ⁴ Munuswamy K, Alpert MA, Martin RH, Whiting RB, Mechlin NJ. Sensitivity and Specificity of Commonly Used Electrocardiographic Criteria for Left Atrial Enlargement Determined by M-Mode Echocardiography. Am J Cardiol. 1984;53(6):829-32. doi: 10.1016/0002-9149(84)90413-2.
  » https://doi.org/10.1016/0002-9149(84)90413-2
• ⁵ Hazen MS, Marwick TH, Underwood DA. Diagnostic Accuracy of the Resting Electrocardiogram in Detection and Estimation of Left Atrial Enlargement: An Echocardiographic Correlation in 551 Patients. Am Heart J. 1991;122(3 Pt 1):823-8. doi: 10.1016/0002-8703(91)90531-l.
  » https://doi.org/10.1016/0002-8703(91)90531-l
• ⁶ Alpert MA, Munuswamy K. Electrocardiographic Diagnosis of Left Atrial Enlargement. Arch Intern Med. 1989;149(5):1161-5.
• ⁷ Josephson ME, Kastor JA, Morganroth J. Electrocardiographic Left Atrial Enlargement. Electrophysiologic, Echocardiographic and Hemodynamic Correlates. Am J Cardiol. 1977;39(7):967-71. doi: 10.1016/s0002-9149(77)80209-9.
  » https://doi.org/10.1016/s0002-9149(77)80209-9
• ⁸ Luna AJB. Block at the Auricular Level. Rev Esp Cardiol. 1979;32(1):5-10.
• ⁹ Luna AB, Platonov P, Cosio FG, Cygankiewicz I, Pastore C, Baranowski R, et al. Interatrial Blocks. A Separate Entity from Left Atrial Enlargement: A Consensus Report. J Electrocardiol. 2012;45(5):445-51. doi: 10.1016/j.jelectrocard.2012.06.029.
  » https://doi.org/10.1016/j.jelectrocard.2012.06.029
• ¹⁰ Conde D, Baranchuk A. Interatrial Block as Anatomical-Electrical Substrate for Supraventricular Arrhythmias: Bayés syndrome. Arch Cardiol Mex. 2014;84(1):32-40. doi: 10.1016/j.acmx.2013.10.004.
  » https://doi.org/10.1016/j.acmx.2013.10.004
• ¹¹ Ariyarajah V, Apiyasawat S, Spodick DH. Optimal P-Wave Duration for Bedside Diagnosis of Interatrial Block. Ann Noninvasive Electrocardiol. 2006;11(3):259-62. doi: 10.1111/j.1542-474X.2006.00113.x.
  » https://doi.org/10.1111/j.1542-474X.2006.00113.x
• ¹² Bayés-de-Luna A, Bacharova L. New Electrocardiographic Aspects of the P Wave: Its Value in Clinical Cardiology. Ann Noninvasive Electrocardiol. 2023;28(3):e13053. doi: 10.1111/anec.13053.
  » https://doi.org/10.1111/anec.13053
• ¹³ 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):1755-9. doi: 10.1016/j.amjcard.2016.03.013.
  » https://doi.org/10.1016/j.amjcard.2016.03.013
• ¹⁴ Martínez-Sellés M, Elosua R, Ibarrola M, Andrés M, Díez-Villanueva P, Bayés-Genis A, et al. Advanced Interatrial Block and P-Wave Duration are Associated with Atrial Fibrillation and Stroke in Older Adults with Heart Disease: The BAYES Registry. Europace. 2020;22(7):1001-8. doi: 10.1093/europace/euaa114.
  » https://doi.org/10.1093/europace/euaa114
• ¹⁵ Alencar JN. Tratado de ECG. Salvador: Sanar; 2022.

Publication Dates

• Publication in this collection
  01 June 2026
• Date of issue
  2026

History

• Received
  02 Dec 2025
• Reviewed
  10 Dec 2025
• Accepted
  10 Dec 2025