Impairment of heart rate variability during paclitaxel therapy

BACKGROUND. Paclitaxel, which has been reported to be effective in treating metastatic breast carcinoma and advanced ovarian carcinoma, has been assoc iated with cardiac side effects. Therefore, the effect of paclitaxel on car diovascular autonomic regulation was studied. METHODS, Twenty-four-hour ambulatory electrocardiogram measurements were re corded twice from 14 women with breast or ovarian carcinoma: once before pa clitaxel treatment and once on the day after the second chemotherapy course . Heart rate variability (HRV) was assessed with spectral analysis. For the frequency domain analysis, HRV was assessed in the Very low (0.005-0.040 h ertz [Hz]), low (0.040-0.150 Hz), and high frequency (0.150-0.400 Hz) spect ral components. RESULTS. The ratio between low frequency and high frequency HRV decreased ( daytime Values of 2.7% [standard deviation (SD) 1.6] vs. 1.7% [SD 0.9]; P = 0.0098) after 2 courses of paclitaxel. The circadian fluctuation of HRV al so decreased in all studied frequency components. CONCLUSIONS. The observed changes in spectral characteristics suggest that autonomic modulation of the heart rate is impaired after paclitaxel therapy . However, from these data it is not clear whether the observed changes are permanent or whether autonomic cardiac function returns to normal some tim e after treatment. Further studies are needed to examine whether these indi ces based on HRV can be used to detect those patients at risk for cardiac s ide effects during chemotherapy. (C) 2000 American Cancer Society.