Relationship between resting heart rate and metabolic risk factors in breast cancer patients.

BACKGROUND: Higher resting heart rate (RHR) was associated with poor prognosis in breast cancer survivors, but the mechanism underlying such association has not been fully studied. We investigated the association between RHR and metabolic risk factors in stage I-III breast cancer survivors.

METHODS: Among 11,013 women diagnosed with breast cancer between 2005 and 2013 at the Severance hospital in Seoul, Korea, a total of 4980 patients met our inclusion criteria for the final analysis. Multivariable linear regressions were used to examine the association between RHR and metabolic risk factors, including systolic blood pressure (SBP), diastolic blood pressure (DBP), glucose, triglyceride (TG), total cholesterol, high density lipid cholesterol (HDLC), and low density lipid cholesterol.

RESULTS: The results showed that RHR had significant linear associations with SBP (p = .02), DBP (p < .001), TG (p < .001), glucose (p < .001), and HDL-C (p < .001). Compared to participants in the lowest quintile of RHR (<68 beat per min (bpm)), participants in the highest quintile (≥85 bpm) had higher DBP by 4 mmHg, TG by 13 mg/dl, and glucose by 5 mg/dl after adjusting for potential confounders. Further subgroup analyses showed that the association of RHR may differ by age and menopausal status for fasting glucose and cancer stage, chemotherapy, estrogen and progesterone receptor status for TG.

CONCLUSIONS: We observed a strong positive association of RHR with fasting glucose, TG, and DBP in breast cancer survivors, which may potentially explain the association between RHR and breast cancer prognosis.