Periodic repolarization dynamics and deceleration capacity in heart transplant recipients
B Knap, M Messner, F Hofer, M Schreinlechner, D Pavluk, A BauerAbstract
Introduction
Periodic repolarization dynamics (PRD) is an ECG-based risk marker reflecting sympathetic-activity related modulation of ventricular repolarization. (1) Deceleration capacity of heart rate (DC) represents an integral measure of predominantly vagally mediated heart rate dynamics. (2) Following heart transplantation (HTx), autonomic reinnervation remains incomplete, yet its long-term electrophysiological consequences are poorly understood.
Methods
We included 19 stable patients two to five years after orthotopic heart transplantation who underwent standardized 30 min high resolution ECG recordings in Frank lead configuration. PRD and DC were quantified using established algorithms and compared with age-matched controls. Group comparisons were performed using Wilcoxon rank-sum tests and Fisher’s exact tests, as appropriate.
Results
HTx recipients had a mean age of 59.0 ± 9.6 years and 5 (26.3 %) were female compared with mean age of 61.5 ± 7.8 years in the control group (p = 0.802), of whom 8 (57.1 %) were females (p = 0.148). PRD was significantly higher in HTx recipients compared to controls (4.88 [IQR 6.86] vs 1.67 [IQR 2.03] deg²; p = 0.007). In contrast, DC did not differ significantly between groups (1.45 [IQR 0.85] vs 1.43 [ IQR 1.12] ms; p = 0.743).
Conclusion
PRD is significantly increased years after HTx, whereas DC remains comparable to age-matched controls. This dissociation suggests enhanced sympathetic modulation of ventricular repolarization, potentially reflecting heterogeneous sympathetic re-innervation without detectable changes in global heart rate deceleration dynamics. Future studies are needed to evaluate the prognostic implications of PRD after HTx.