Cardiac fibrosis contributes to electrical conduction disturbances, yet its specific impact on conduction remains unclear, hindering predictive insight into cardiac electrophysiology and arrhythmogenesis. Arrhythmogenic cardiomyopathy is associated with fibrotic remodeling, and it accounts for most cases of stress-related arrhythmic sudden death. Here we develop a correlative imaging approach to integrate macroscale cardiac electrophysiology with three-dimensional microscale reconstructions of the ventricles. We apply this tool to a desmoglein-2 mutant mouse model to characterize the dynamics of conduction wavefronts and relate them to the underlying structural substrate. We observed that conduction through fibrotic tissue areas shows a frequency-dependent behavior, where conduction fails at high stimulation frequencies; this promotes reentrant arrhythmias, even in regions that were electrophysiologically inconspicuous at lower stimulation rates. We found that fibrotic areas undergo electrophysiological remodeling that acts as a low-pass filter for conduction, quantitatively explained by computational models informed by structural data. Collectively, our study provides a structure-function mapping pipeline and describes a pro-arrhythmogenic mechanism in arrhythmogenic cardiomyopathy.