Loss of frequency modulation of RT variability in patients with chest pain and normal coronary arteriograms

This paper characterizes the magnitude, dynamics and frequency modulation of RR- and RT-interval variability in 20 patients with angina, who had documented normal coronary arteries. Results were compared to those obtained in 21 healthy volunteers. In patients with angina, RR variability was reduced, especially in the high-frequency domain, and its complexity was lower. RT variability had similar magnitude, spectral measures values and complexity. Significant magnitudes of the coherence spectra (0.806+/-0.163) were found to be strongly related to frequency of respiration only in controls, while in the patients they were not substantial (0.466+/-0.250). Also the complexity of RR and RT variabilities correlated significantly to the frequency of respiration only in healthy subjects. In contrast, such relationships in angina patients with normal coronary arteriograms were not significant.