Measured and Simulated P Waves in Normal Subjects Reflect Complex Atrial Anatomy

Introduction: The shape of the P wave can yield important information about the substrate of atrial fibrillation (AF). On the routine 12-lead ECG, P waves have a smooth appearance. Computer simulation studies with realistic atrial models have shown highly complex P-wave shapes with details that were linked to structural features of the atria. We assessed the true shape of the P wave in control subjects. Methods: We recorded 184-channel high-resolution ECGs in 6 healthy volunteers and averaged over 300 beats for each. Beats were aligned on their P waves. Alignment was based on a compound signal of all 184 channels to reduce the effect of noise on alignment. In addition, 12-lead ECGs were simulated using a single patient-tailored heart-torso model with detailed atrial anatomy. Results: Averaging reduced the noise level to less than 2 microvolt (uV) peak-to-peak. Signal features of a few uV amplitude and less than 5 milliseconds (ms) duration could be reliably distinguished. Measured P waves had 4 to 5 separate peaks that were reproducible between recordings. Simulated P waves demonstrated similar complexity, which was related to structural discontinuities in the computer model of the atria. Conclusions: The true shape of the P wave is very irregular and reflects the complex anatomy of the atria. High-resolution electrocardiography is necessary to reliably assess P-wave shape.Optimization of noninvasive assessment of the substrate for atrial fibrillatio

The ECG as a tool to determine atrial fibrillation complexity

The use of the ECG for atrial fibrillation (AF) in clinical daily practice is still limited to its diagnosis. Recent research shows however that ECG-derived parameters can also be used to assess the spatiotemporal properties of AF. Specifically, the complexity of the f-waves in the ECG reflects the complexity of the fibrillatory conduction during AF and therefore can be used for quantification of the degree of electrophysiological alterations in the atria. This information might be useful for guiding AF therapy and might form the basis for classification of AF. This review focuses on technical and mathematical aspects of ECG-based atrial complexity assessment and its potential ability to guide treatment strategies