Concordance and Divergence Between Simultaneous Optical and Electrical Mapping of Cardiac Arrhythmias in Langendorff-Perfused Rabbit Hearts

Abstract: Optical mapping with voltage-sensitive dyes and contact electrical mapping with multi-electrode arrays (MEAs) are the two principal experimental techniques for studying cardiac arrhythmia mechanisms, yet a systematic evaluation of their agreement across a range of rhythm complexities has been lacking. This study used simultaneous panoramic optical and contact electrical recordings from Langendorff-perfused rabbit hearts (n = 16 analysable preparations) to compare activation patterns, dominant frequency (DF), and organization index (OI) across organized rhythms (atrial tachycardia [AT], ventricular tachycardia [VT], ventricular alternans) and disorganized rhythms (atrial fibrillation [AF], ventricular fibrillation [VF]). During organized rhythms, both modalities agreed on the earliest activation site, propagation direction, DF (within 0.5 Hz), and OI. During fibrillation, the modalities diverged in local activation time (LAT) maps, phase singularity detection, and spectral metrics, with divergence more pronounced during VF than AF. Optical mapping showed a rotor during VF that was invisible to the 16-electrode array, while optical OI marginally exceeded electrical OI during AF. These findings establish that the reliability of cross-modality comparison depends on rhythm complexity and define the conditions under which sparse electrical recordings can and cannot substitute for high- resolution optical data.