A novel signal distribution-based approach to characterize atrial cardiomyopathy

Modern endocardial contact-mapping displays myocardial substrate based on impaired signal amplitude (SA). Previous methods for characterizing left atrial (LA) myocardium rely on arbitrary thresholds and manual tracing of low-voltage areas. The amplitude and distribution of signals above these thresholds remain unexamined. This study aimed to develop novel parameters for characterizing LA myocardium and LA cardiomyopathy (AC) based on the analysis of the full distribution of SAs across the entire LA. We retrospectively identified 50 adult patients who underwent primary pulmonary vein isolation (PVI) for paroxysmal or persistent AF. Selection criteria were (i) electroanatomical mapping (EA) in sinus rhythm (SR) with ≥5000 points/map; (ii) transthoracic echocardiography (TTE) acquired in SR within 48 h prior to PVI. Exclusion criterion was previous LA ablation. The pulmonary veins were manually excised from the EA maps, and the SA of each point was plotted. A novel set of variables describing the voltage distribution across the entire LA was analyzed. Based on the assumption of healthier and sicker individuals within the study cohort, cluster analysis was performed for every voltage distribution variable using Gaussian mixture modelling. Associations with total LVA, NT-proBNP, CHA₂DS₂-VA score and LA TTE parameters were assessed (proof of function). AF recurrence rates following PVI were investigated. The mean age of the studied sample (n = 48) was 62.5 ± 11 years, 62.5% were men, 66.7% showed persistent AF, median CHA2DS2-VA score was 1.5 (1, 3) and NT-proBNP was 190 (68, 413) pg/ml. A median of 5711 (5214, 6998) points/map were acquired. In this all-comer PVI cohort, mean SA was 2.4 ±0.96 mV, variance 2.27 ±1.07 mV2, skewness 1.43 ±0.59 and kurtosis 6.17 ±3.24. Variables did not differ between gender and subtypes of AF. For each variable, the sample was successfully stratified into groups mild and severe AC. Groups differed regarding NT-proBNP levels, CHA2DS2-VA score, LA TTE parameters and AF recurrence. We identified novel parameters to characterize LA myocardium by analyzing the full distribution of SAs across the entire LA using an open, investigator-independent strategy. SA-independent features including NTproBNP, CHA2DS2-VA score and echocardiographic measures of LA function consistently differed between mild and severe AC groups stratified by these novel parameters. This approach may not only facilitate a more precise characterization of AC but also advance automated analytic methods applicable during endocardial mapping and ablation of AF.