Long-term effects of neck irradiation on cardiovascular autonomic function: A study in nasopharyngeal carcinoma patients after radiotherapy

Introduction: Baroreflex failure has been reported as a late sequalum of neck radiotherapy. In this study we investigated cardiovascular autonomic function in patients after neck radiotherapy to determine predictive factors associated with outcome. Methods: Eighty-nine patients with nasopharyngeal carcinoma were evaluated ≥6 months after radiotherapy for cardiovascular autonomic function and compared with 48 control subjects. Inflammatory markers and carotid intima-media thickness were also assessed. Results: Autonomic parameters of heart rate response to deep breathing and Valsalva ratio were significantly lower in the patient group. Cardiovascular autonomic impairment was generally mild with relative sparing of the efferent cardiovagal pathway. By univariate and multivariate analyses, the time after radiotherapy and C-reactive protein level were significantly associated with the degree of cardiovascular autonomic dysfunction. Conclusions: Radiation-induced cardiovascular autonomic impairment is a dynamic and progressive process that occurs long after radiotherapy. Chronic inflammation plays a major role in this process.