Objectives: To assess the prognostic value of heart rate response to exercise in adult congenital heart disease (ACHD) patients.
Background: An abnormal heart rate response to exercise is related to autonomic dysfunction and may have prognostic implications in ACHD.
Methods: We identified 727 consecutive ACHD patients (mean age [+/- SD] 33 +/- 13 years) with varying diagnoses and without pacemakers. Peak oxygen consumption (peak VO2), resting heart rate, and the increase in heart rate from resting level to peak exercise ("heart rate reserve") were measured. We also quantified the decrease in heart rate ("heart rate recovery") after cessation of exercise.
Results: During a median follow-up of 28 months, 38 patients died. Lower values of heart rate reserve, peak heart rate, heart rate recovery, and peak VO2 (p < 0.01 for each) were associated with increased mortality in univariate analysis. Furthermore, heart rate reserve predicted mortality independently of antiarrhythmic therapy, functional class, and peak VO2. Stratifying patients by diagnostic groups revealed that a lower heart rate reserve was also associated with a greater risk of death in patients with complex anatomy, Fontan circulation, and tetralogy of Fallot (p < 0.05 for each).
Conclusions: An abnormal heart rate response to exercise identifies ACHD patients with a higher risk of mortality in the midterm, even after accounting for antiarrhythmic medication and exercise capacity. Heart rate reserve is a simple and inexpensive way to identify ACHD patients at higher mortality risk.