Abstract 13267: Impairment of Heart Rate Recovery after Peak Exercise Predicts Poor Outcome after Pediatric Heart Transplantation
Background: A blunted heart rate recovery (HRR) from peak exercise is associated with adverse outcome in adults with ischemic heart disease. We assessed HRR after pediatric heart transplantation (HT) and its prognostic utility.
Methods: Between 2004 and 2010 we performed 360 maximal exercise tests (median 2 tests/patient, range 1 to 7) in 128 children (66 males; age at test 14±3 years; 6.0±4.1 years after HT) who received HT (age 8.5±5.1 years) due to cardiomyopathy (66%) or congenital heart defects (34%). The change in heart rate from peak exercise to 1 minute of recovery was measured as HRR. Due to age variations in HRR, Z scores of HRR were calculated in HT patients using normal values obtained in 160 healthy children. Outcome events included death or re-HT.
Results: HRR was impaired soon after HT (average in first 2 years Z = -1.9±3.5) but improved in the early years after HT at a rate of Z +0.52/year, such that HRR Z score normalized in most patients by 6 years after HT (average value 0.6±1.8). A subsequent decline in HRR Z score was noted from 6 years after HT with a slope of Z = -0.11/year. After 27±15 months from the most recent exercise test 19 patients died or were re-HT. HRR Z score was the only predictor of death/re-HT (p=0.0001) whereas age at HT, reason for HTx, time since HT, age at test, gender, percentage of predicted peak heart rate or percentage of predicted peak oxygen uptake were not. Patients in the lowest quartile of HRR Z score had a much higher 5-year mortality than patients with higher HRR Z score (event free rate 29% versus 84%, HR 7.0, p=0.0013).
Conclusion: HRR is blunted soon after HT but normalizes at around 6 years, possibly as a result of parasympathetic re-innervation of the graft, but then declines. This late decline in HRR Z score is associated with worse outcome. The etiology of this warrants further investigation but coronary allograft vasculopathy may be implicated.
- © 2012 by American Heart Association, Inc.