Evaluation of Multi-Lead ECG Markers to Track Changes in Dispersion of Ventricular Repolarization in the Intact Human Heart

Abstract

Dispersion of ventricular repolarization (DRT) is an important factor contributing to the vulnerability to life-threatening arrhythmias. An accurate non-invasive methodology for its estimation would contribute to improve risk-prediction. We assessed 3 multi-lead ECG markers to track changes in DRT using intra-cardiac data recorded in patients with structurally normal ventricles. Changes in DRT were measured with intra-cardiac unipolar electrograms (UEG) simultaneously recorded in the RV endocardium (RVendo), LV endocardium (LVendo) and LV epicardium (coronary sinus, LVepi) in 10 patients. Standard S1S2 restitution protocols were conducted by pacing from the RVendo (n = 8), LVendo (n = 10) and LVepi (n = 7). DRT was measured as latest minus earliest re-polarization time (RT). In the surface ECG, DRT was estimated from precordial and augmented limb leads as: (1) Interval between the earliest and the latest maximum up-slope of the T-wave (ΔTup); (2) Interval between median T-peak and median T-end (Tpe,med); (3) Interval between the earliest T-peak and latest T-end (Tpe,range). Intra-patient correlation with DRT changes was higher using ΔTup (0.79, 0.66 - 0.89) than Tpe,med (0.61, 0.14 - 0.76, $P$ = 0.001) or Tpe,med(0.71, 0.44 - 0.79, $P$ = 0.054).