Sympathetic reinnervation in cardiac transplant recipients: Prevalence, time course, and association with long-term survival

Background: Partial cardiac sympathetic reinnervation after cardiac transplant has been extensively investigated and evidenced. However, there have been no large-scale, long-term studies evaluating the prevalence, time-course, and association with long-term survival of sympathetic reinnervation of the heart.

Methods: Cardiac transplant recipients (n = 232) were recruited from outpatient clinic at a single transplant center in the United Kingdom. Participants were each tested once for the presence of sympathetic reinnervation of the sinus node using the low-frequency component of power spectral analysis of heart rate variability, with a cutoff defined as 2 standard deviations above the mean for denervated participants (those tested <56 days posttransplant). Time course was calculated based on the timing of testing posttransplant. Patients were then followed up over a period of up to 27 years after transplant for survival analysis.

Results: The overall prevalence of cardiac sympathetic reinnervation in the 225 patients tested >56 days posttransplant was 64.9%. Sympathetic reinnervation primarily occurred in the first 18 months after transplant, with a plateau thereafter. The prevalence in participants tested >18 months posttransplant was 69.6%. In Kaplan-Meier survival analysis, sympathetic reinnervation was associated with significantly improved survival (Log-rank p = 0.019), with a median survival time for reinnervated patients of 19.9 years compared with 14.4 years for the denervated group.

Conclusions: Sympathetic reinnervation of the sinus node occurs mostly within 18 months of transplant, is found in 70% of cardiac transplant recipients tested >18 months posttransplant, and is associated with significantly improved long-term survival.