Cardiac ventricular arrhythmias - electrical activation abnormalities that can result in sudden cardiac death - are difficult to manage with ablative treatment as many have complex, non-sustained 4D (volume over time) activation patterns that cannot be fully captured by existing electroanatomic mapping systems. In this study, we describe the use of acoustoelectric cardiac imaging (ACI) for high resolution, beat-to-beat mapping of electrical dynamics in an in vivo swine model. Beat-to-beat variability was tracked in the swine; the variation in the peak magnitude, peak myocardial location, peak time, and SNR across 20 beats were measured as 5.27 ± 0.68 µV, 3.32 ± 0.41 mm from the epicardium, -2.73 ± 0.38 ms from the peak EGM, and 25.3 ± 8.1 dB, respectively. Additionally, propagation velocity was tracked across four pigs and was calculated as 0.153 ± 0.108 m/s along the endocardial-epicardial axis and 0.123 ± 0.098 m/s along the apicobasal axis. This study suggests that ACI has the potential to improve ablation treatment of arrhythmias through higher resolution, beat-to-beat pre-ablation mapping and characterization of ventricular arrhythmias.