Is neuropathic pain associated with cardiac sympathovagal activity changes in patients with breast cancer?

Objective Heart rate variability (HRV) is a good indicator of the autonomic nervous system (ANS) activity. A few studies have been conducted recently and have shown a relationship between reduced HRV and conditions that lead to neuropathic pain (NP). In this study, we aimed to investigate whether NP is associated with changes in cardiac sympathovagal activity in patients with breast cancer (BC). Methods We used the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) questionnaire to evaluate NP in 70 patients with BC. The patients were subjected to a 24-h Holter ECG monitorization to determine heart rate variability (HRV). Standard deviation (SD) of the normal-to-normal RR intervals (SDNN), SD of the mean of the RR intervals (SDAAN), mean of the SD of the NN interval (SDNN Index), low-frequency component/high-frequency component ratio (LF/HF), and the mean heart rate of the patients were recorded. Results According to the LANSS questionnaire, 18 (25.7%) of the patients were classified as NP (+). The SDNN (P = 0.001), SDAAN (P = 0.003), and SDDN index (P = 0.007) were significantly lower in patients with NP than in patients without NP, whereas LF/HF ratio (P = 0.000) and mean heart rate were found to be significantly higher in patients with NP (P = 0.006). Conclusion According to our findings, NP (+) patients with BC had increased cardiac sympathetic activity, which was suggested to be associated with increased cardiovascular morbidity and mortality.