Resting Heart Rate Influences Right Ventricular Volume in Repaired Tetralogy of Fallot

The aim of this study is to examine the impact of heart rate (HR) on right ventricular end-diastolic volume indexed to body surface area (RVEDV_i) in patients with repaired tetralogy of Fallot (TOF). In this cross-sectional study, an institutional database search identified all patients with repaired TOF who underwent cardiac magnetic resonance (CMR) and had a Holter study within 3 months. The association of HR on Holter, HR at the time of CMR, and other clinical and CMR parameters on RVEDV_i was explored with univariate and then multivariable models. In the study group (n = 161, median age 23 years), a lower mean Holter HR was associated with a larger RVEDV_i (p = 0.004). In a model that also included pulmonary regurgitation fraction, tricuspid regurgitation grade, RV ejection fraction, age at CMR, and gender, mean Holter HR remained associated with RVEDV_i (p < 0.0001); for a decrease of 1 bpm, mean RVEDV_i increased by 1.09 ml/m². When limiting to those with a Holter within 5 days of CMR (n = 70), the impact of mean Holter HR on RVEDV_i was stronger (−1.9 ml/m²/bpm). HR at time of CMR had a significant but less pronounced relationship to RVEDV_i (−0.58 ml/m²/bpm, p = 0.002). In conclusion, in repaired TOF patients, a lower HR was significantly associated with a larger RVEDV_i. This relationship was stronger with a shorter time interval between the Holter and CMR, and stronger for the mean HR on Holter than for the HR at CMR. Accounting for HR in the interpretation of RVEDV_i may impact decisions regarding pulmonary valve replacement and the interpretation of serial CMR data.