Poincaré Plot Image and Rhythm-Specific Atlas for Atrial Bigeminy and Atrial Fibrillation Detection

A detector based only on RR intervals capable of classifying other tachyarrhythmias in addition to atrial fibrillation (AF) could improve cardiac monitoring. In this paper a new classification method based in a 2D non-linear RRI dynamics representation is presented. For this aim, the concepts of Poincar Images and Atlases are introduced. Three cardiac rhythms were targeted: Normal sinus rhythm (NSR), AF and atrial bigeminy (AB). Three Physionet open source databases were used. Poincar images were generated for all signals using different Poincar plot configurations: RR, dRR and RRdRR. The study was computed for different time window lengths and bin sizes. For each rhythm, 80% of the Poincar Images were used to create a reference rhythm image, a Poincar atlas. The remaining 20% patients were classified into one of the three rhythms using normalized mutual information and 2D correlation. The process was iterated in a tenfold cross-validation and patient-wise dataset division. Sensitivity results obtained for RRdRR configuration and bin size 40 ms, for a 60 s time window 94.35%3.68, 82.07%9.18 and 88.86.79 with a specificity of 85.52%7.46, 95.91%3.14, 96.10%2.25 for AF, NSR and AB respectively. Results suggest that a rhythm's general RRI pattern may be captured using Poincar Atlases and that these can be used to classify other signal segments using Poincar Images. In contrast with other studies, the former method could be generalized to more cardiac rhythms and does not depend on rhythm-specific thresholds.