Elevated Heart Rate is Associated with Increased Mortality and Rejection in Pediatric Heart Transplant Recipients

Purpose: Elevated heart rate is associated with adverse outcomes in patients with heart failure.Heart transplant recipients often have elevated heart rate; however, the long-term associations of elevated heart rate with clinical outcomes are unknown. Methods:The records of all pediatric (21 years) heart transplant recipients at our institution were reviewed.Patients who died or lacked a clinic visit within one year following heart transplant were excluded, as were those with a permanent pacemaker.Heart rate was collected from outpatient electrocardiograms and converted to Z-scores using age-specific normative data.The cohort was divided into elevated and normal heart rate groups, with elevated heart rate defined as average HR Z-score 95th percentile during the first post-transplant year.Outcomes, including survival, rejection, and cardiac allograft vasculopathy were compared between groups.Results: A total of 110 pediatric heart transplants were included (median age 11.4 years; 62% male).Thirty-six (33%) had elevated heart rate.The elevated heart rate group was older (15.8 vs.6.1 years, p<0.001) and had shorter follow-up (3.0 vs. 4.7 years, p=0.007).Elevated heart rate was independently associated with increased risk of death (HR 3.98, 95% CI 1.20-13.2,p=0.024) and a composite of death or rejection (HR 3.31, 95% CI 1.47-7.45,p=0.004), but not cardiac allograft vasculopathy. Conclusion:Among patients who survive the first year after pediatric heart transplantation, elevated heart rate during the first post-transplant year is independently associated with increased risk of mortality and rejection.Further work is necessary to determine whether pharmacologic modulation mitigates this risk.