Endocardial and epicardial mapping revealed significant transmural repolarization time dispersion across dense scar compared to normal tissue (ΔRT 22 ms vs 5 ms, P<0.001).
Observational (n=6)
Do areas of myocardial scar have prolonged action potential duration and transmural heterogeneity compared to normal tissue in patients undergoing VT ablation?
Myocardial scar areas exhibit prolonged action potential duration and significant transmural repolarization dispersion, which may contribute to the initiation of ventricular tachycardia.
p-value: p=<0.001
AIMS: Differences of action potential duration (APD) in regions of myocardial scar and their borderzones are poorly defined in the intact human heart. Heterogeneities in APD may play an important role in the generation of ventricular tachycardia (VT) by creating regions of functional block. We aimed to investigate the transmural and planar differences of APD in patients admitted for VT ablation. METHODS AND RESULTS: Six patients (median age 53 years, five male); (median ejection fraction 35%), were studied. Endocardial (Endo) and epicardial (Epi) 3D electroanatomic mapping was performed. A bipolar voltage of 1.5 mV as normal. Decapolar catheters were positioned transmurally across the scar borderzone to assess differences of APD and repolarization time (RT) during restitution pacing from Endo and Epi. Epi APD was 173 ms in normal tissue vs. 187 ms at scar borderzone and 210 ms in dense scar (P < 0.001). Endocardial APD was 210 ms in normal tissue vs. 222 ms in the scar borderzone and 238 ms in dense scar (P < 0.01). This resulted in significant transmural RT dispersion (ΔRT 22 ms across dense transmural scar vs. 5 ms in normal transmural tissue, P < 0.001), dependent on the scar characteristics in the Endo and Epi, and the pacing site. CONCLUSION: Areas of myocardial scar have prolonged APD compared with normal tissue. Heterogeneity of regional transmural and planar APD result in localized dispersion of repolarization, which may play an important role in initiating VT.
Srinivasan et al. (Thu,) conducted a observational in Ventricular tachycardia (n=6). Endocardial and epicardial 3D electroanatomic mapping vs. Normal tissue was evaluated on Differences in action potential duration (APD) and repolarization time (RT) dispersion (p=<0.001). Endocardial and epicardial mapping revealed significant transmural repolarization time dispersion across dense scar compared to normal tissue (ΔRT 22 ms vs 5 ms, P<0.001).