ABNORMAL HEART-RATE-VARIABILITY AS A MANIFESTATION OF AUTONOMIC DYSFUNCTION IN HEMISPHERIC BRAIN INFARCTION

Background and Purpose Abnormal heart rate variability is related to p rognostically unfavorable ventricular arrhythmias and sudden arrhythmi c death in coronary artery disease. Short-term electrocardiographic (E GG) recordings have shown similar abnormalities of heart rate variabil ity in patients with acute stroke. However, there is no information re garding the clinical significance of these abnormalities and of heart rate variability in long-term ECG recordings in stroke. Methods In thi s prospective study, we analyzed the time domain and frequency domain measures of heart rate variability from 24-hour ECG recordings in 31 c onsecutive patients with hemispheric brain infarction in the acute pha se and at 1 and 6 months after the infarction and in 31 age- and sex-m atched healthy control subjects. Results All the measured components o f heart rate variability, ie, standard deviation of RR intervals (P<.0 01), total power (P<.0001), very-low-frequency power (P<.0001), low-fr equency power (P<.001), and high-frequency power (P<.05), were signifi cantly lower than those of the control subjects in both the acute phas e and 1 and 6 months later. Impaired heart rate variability correlated with the severity of neurological deficits and disability. In five pa tients with increased intracranial pressure due to large brain infarct ion, no relevant spectral components were found. Conclusions Hemispher ic brain infarction seems to cause significant long-lasting damage to the cardiovascular autonomic regulatory system manifested as abnormali ties of heart rate variability. Distorted heart rate variability in th e acute phase of stroke may be prognostically unfavorable.