Abstract Body: Background: Steep local repol gradients are critically more important than global repol changes. Activation recovery intervals (ARI) of unipolar electrograms (Uni) estimation of repol integrate far-field signals and may not detect local gradients. Multielectrode array catheters have allowed for the innovation of principal component-referenced Uni (Uni^PCR), which attenuates far-field contribution in electrical signals. Here we apply this concept to estimate global and local repol changes.
Hypothesis: We assessed the hypothesis that Uni^PCR ARI will correlate to optical APD80 better than Uni ARI and Uni^PCR ARI will more accurately detect local repol changes than Uni ARI by attenuating the far-field.
Aim: We aimed to validate Uni^PCR as a superior alternative to the Wyatt ARI method on Uni with optical APD80 as reference in detecting local repol changes.
Methods: To validate Uni^PCR ARI for detecting global repol changes, we conducted simultaneous optical and electrical mapping in a rabbit model (n=3) following pinacidil/ibutilide infusion and compared optical APD to Uni vs Uni^PCR ARIs. To alter repol locally, we performed epicardial mapping in pig Langendorff experiments (n=4) and topically administered lidocaine at the center of the electrode array. We compared the changes in ARI from Uni vs. Uni^PCR before and after application of the drug.
Results: When repol is altered globally, there is a high correlation between both Uni^PCR and optical APD80 (slope = 0.98, R² = 0.90) and Uni and optical APD80 (slope = 0.99, R² = 0.91). When there is a local repol gradient, a greater difference in percent change near vs. far from the application site was observed in the Uni^PCR (32.0%, p <0.0001) compared to the Uni (5.2%, p = 0.0144). Uni^PCR ARI (AUC-ROC = 0.9) more accurately predicted areas near vs. far from the application site than Uni ARI (AUC-ROC = 0.7).
Conclusion: Global changes in repol can be detected by both Uni and Uni^PCR ARI. However, Uni^PCR is more sensitive to local repol gradients than Uni ARI. Implementing such mapping technology has greater implications for defining arrhythmogenicity of regional myocardium.