Personalized voltage maps guided by cardiac magnetic resonance in the era of high-density mapping

Background Voltage mapping could identify the conducting channels potentially responsible for ventricular tachycardia (VT). Standard thresholds (0.5-1.5 mV) were established using bipolar catheters. No thresholds have been analyzed with high density mapping catheters. In addition, channels identified by cardiac magnetic resonance (CMR) has been proven to be related with VT. Objectives To analyze the diagnostic yield of a personalized voltage map using CMR to guide voltage thresholds adjustment. Methods All consecutive patients with scar-related VT undergoing ablation after CMR (October 2018-December 2020) were included. First, personalized CMR-guided voltage thresholds were defined systematically according to scar and channels distribution. Second, to validate these new thresholds, a comparison with standard thresholds (0.5-1.5mV) was carried out. Tissue characteristics of areas identified as deceleration zones (DZ) were recorded for each pair of thresholds. In addition, the relation of VT circuits with voltage channels was also analyzed for both maps. Results 32 patients were included (age 66.6±11.2 years; 78.1% ischemic cardiomyopathy). Overall, 52 DZs were observed:44.2% were identified as border zone tissue with standard cutoffs vs. 75.0% using personalized voltage thresholds (p=0.003). Of 31 VT isthmuses detected, only 35.5% correlated with a voltage channel with standard thresholds vs. 74.2% using adjusted thresholds (p=0.005). Adjusted cutoff bipolar voltages that better matched CMR were 0.51±0.32 and 1.79±0.71mV with very high interindividual variability (from 0.14-1.68mV to 0.7-3.21mV). Conclusion Personalized voltage CMR-guided maps enable a clear better identification of the substrate with a higher correlation with both DZs and VT isthmuses than conventional voltage maps using fixed thresholds.