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Influence of left atrial size on P-wave morphology: differential effects of dilation and hypertrophy
Robin Andlauer1, Gunnar Seemann2,3, Lukas Baron1
1Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), Kaiserstr. 12, Karlsruhe, Germany.
Insights
Left atrial enlargement increases atrial fibrillation risk. While dilation has minor P-wave effects, hypertrophy significantly impacts P-wave terminal force, suggesting its utility in detecting atrial hypertrophy.
Area of Science:
- Cardiology
- Biomedical Engineering
- Computational Modeling
Background:
- Chronic left atrial enlargement (LAE) is a significant risk factor for atrial fibrillation.
- Current electrocardiogram (ECG) criteria for diagnosing LAE have limited accuracy.
- Understanding the distinct ECG P-wave effects of atrial dilation versus hypertrophy is crucial.
Purpose of the Study:
- To differentiate the ECG P-wave alterations caused by left atrial dilation (LAD) and left atrial concentric hypertrophy (LACH).
- To assess the diagnostic potential of P-wave characteristics for LAE subtypes.
- To improve ECG-based risk stratification for atrial fibrillation.
Main Methods:
- Computational modeling of 72 human atrial anatomical variants.
- Simulated left atrial dilation (up to 100% volume increase) and concentric hypertrophy (up to 3.3 mm wall thickening).
- Derived P-waves from simulated atrial excitation propagation and body surface ECG computation.
Main Results:
- Left atrial dilation showed variable effects on P-wave duration (PWd), prolonging it in some subjects but shortening or causing variable changes in others.
- Left atrial concentric hypertrophy consistently increased P-wave terminal force in lead V1 (PTF-V1) across all subjects, without affecting PWd.
- Combined hypertrophy and dilation generally amplified the hypertrophy-induced increase in PTF-V1.
Conclusions:
- Isolated left atrial dilation has minimal impact on current P-wave criteria (PWd, PTF-V1), explaining their limited clinical utility for detecting LAE.
- P-wave terminal force in lead V1 may serve as a more sensitive ECG indicator for left atrial myocardial hypertrophy.
- Distinguishing between atrial dilation and hypertrophy is key for accurate ECG-based LAE assessment.
Aims:
Chronic left atrial enlargement (LAE) increases the risk of atrial fibrillation. Electrocardiogram (ECG) criteria might provide a means to diagnose LAE and identify patients at risk; however, current criteria perform poorly. We seek to characterize the potentially differential effects of atrial dilation vs. hypertrophy on the ECG P-wave.
Methods And Results:
We predict effects on the P-wave of (i) left atrial dilation (LAD), i.e. an increase of LA cavity volume without an increase in myocardial volume, (ii) left atrial concentric hypertrophy (LACH), i.e. a thickened myocardial wall, and (iii) a combination of the two. We performed a computational study in a cohort of 72 anatomical variants, derived from four human atrial anatomies. To model LAD, pressure was applied to the LA endocardium increasing cavity volume by up to 100%. For LACH, the LA wall was thickened by up to 3.3 mm. P-waves were derived by simulating atrial excitation propagation and computing the body surface ECG. The sensitivity regarding changes beyond purely anatomical effects was analysed by altering conduction velocity by 25% in 96 additional model variants. Left atrial dilation prolonged P-wave duration (PWd) in two of four subjects; in one subject a shortening, and in the other a variable change were seen. Left atrial concentric hypertrophy, in contrast, consistently increased P-wave terminal force in lead V1 (PTF-V1) in all subjects through an enlarged amplitude while PWd was unaffected. Combined hypertrophy and dilation generally enhanced the effect of hypertrophy on PTF-V1.
Conclusion:
Isolated LAD has moderate effects on the currently used P-wave criteria, explaining the limited utility of PWd and PTF-V1 in detecting LAE in clinical practice. In contrast, PTF-V1 may be a more sensitive indicator of LA myocardial hypertrophy.
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