Increased Dispersion of Ventricular Repolarization During Head-Up Tilt Test Late After Orthotopic Heart Transplantation in Humans

LEE, T.-M., et al.: Increased Dispersion of Ventricular Repolarization During Head-Up Tilt Test Late After Orthotopic Heart Transplantation in Humans. Sympathetic reinnervation after heart transplantation may be regionally heterogeneous. It remains undetermined if such heterogeneous reinnervation will result in increased ventricular repolarization dispersion. To determine the changes of ventricular repolarization after transplantation, a 15-minute, 80-degree head-up tilt test was prospectively performed with isoproterenol provocation in 30 patients who were studied within 5 months after transplantation (early group) and 30 patients who were studied ≥12 months (late group). Holter monitor was initiated to evaluate heart rate variability, which was a surrogate of cardiac reinnervation. JT dispersion was defined as the difference between maximal and minimal JT interval measurements occurring among any of the 12 leads on a standard electrocardiogram. No subject had fewer than nine measurable leads. Compared with patients in the early group, the patients in the late group had higher low frequency activity, indicating partial sympathetic reinnervation. Analysis of the electrocardiogram showed that there were significant differences in the corrected JT dispersion in the late group compared with the early group and controls (74 ± 18 vs 56 ± 15 and 55 ± 14 ms, both P