Chemotherapy and Radiation-Associated Cardiac Autonomic Dysfunction.

Abstract

Cardiovascular autonomic dysfunction (AD) among cancer survivors is increasingly being recognized. However, the mechanisms and incidence are poorly understood. In this review, the clinical features, diagnostic modalities, proposed mechanisms, and currently available treatments of cardiovascular AD in cancer survivors are described. Much of our current understanding of cardiovascular AD is based on disease states such as diabetes, multisystem atrophy, and Parkinson's disease. Several non-invasive tests, measurements, and scoring systems have been developed as surrogates for autonomic function, with some even demonstrating associations with all-cause mortality. The mechanism of cardiovascular AD specifically in the cancer population, however, has not been directly studied. The etiology of cardiovascular AD in cancer survivors is likely multifactorial, and proposed mechanisms include direct nerve damage by chemoradiation, the pro-inflammatory state associated with malignancy, and paraneoplastic syndromes. It may also be that cardiovascular AD is an early marker of global cardiomyopathy rather than its own condition. Current pharmacologic options for cardiovascular AD are extrapolated from how it has been treated in other disease processes, and these agents have not been studied in the cancer population or compared head-to-head. Cardiovascular AD in cancer survivors can cause significant debilitation and may be associated with all-cause mortality. Current diagnostic modalities have several limitations, such as standardization and validity. However, given the nonspecific nature of cardiovascular AD, these tools provide an objective marker for diagnosis and tracking treatment response. While the mechanism of cardiovascular AD in cancer survivors has not been directly studied, it may be useful to evoke mechanisms of cardiovascular AD in other disease states such as diabetes, Parkinson's disease, and multisystem atrophy in addition to identifying unique conditions associated with malignancy like a pro-inflammatory state. Until further studies are performed, management of cardiovascular AD as seen in other disease states may serve as a guide for symptom management in cancer survivors.