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 1 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 an 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 an 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 5.44, 95% CI 1.47-20.2, p = 0.011) and a composite of death or rejection (HR 3.06, 95% CI 1.30-7.20, p = 0.010), 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.