Heart rate: an accessible risk indicator in adult congenital heart disease.

Background: Higher resting heart rate has been described as a risk factor for adverse outcome in healthy individuals and cardiovascular patients. The aim of this study was to evaluate resting heart rate as risk factor in adult congenital heart disease (ACHD).

Methods: In this prospective observational cohort study, patients with moderate or complex ACHD were included at routine outpatient visit. Standard 12-lead ECGs were obtained in rest. Heart rate was obtained from the ECG automatically by the Modular ECG Analysis System (MEANS). The primary endpoint was all-cause mortality and the secondary endpoint was a composite of all-cause mortality and heart failure. Survival was derived using the Kaplan-Meier estimator. Subgroups based on heart rate tertiles were compared by the log-rank test. Cox proportional hazards models were adjusted for clinical factors including age, sex and diagnosis (moderate vs complex ACHD).

Results: A total of 556 patients were included (median age 32 years (IQR 24-41), 57.6% male). Mean heart rate was 69±13 bpm. Negative chronotropic medication was used by 74 (13.3%) patients. During a median follow-up of 10.1 (IQR 9.6-10.5) years, 36 patients (6.5%) died and 83 (14.9%) reached the secondary endpoint. Patients with higher heart rates had significantly lower survival and heart failure-free survival. After adjusting for clinical factors, heart rate remained associated with mortality (HR 1.57 per 10 bpm, 95% CI 1.26 to 1.96) and mortality or heart failure (HR 1.33 per 10 bpm, 95% CI 1.13 to 1.57).

Conclusion: Higher heart rate is associated with lower survival and heart failure-free survival in ACHD.