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Long-term evaluation of autonomic tone in patients below 50 years of age with unexplained cerebral infarction: relation to atrial vulnerability.

UNLABELLED
Preliminary studies have described, in young patients with unexplained cerebral infarction, electrophysiological abnormalities similar to those observed in paroxysmal atrial fibrillation. Moreover, in young adults with 'normal' hearts, increased susceptibility to paroxysmal atrial fibrillation with autonomic abnormalities as assessed by heart rate variability analysis have been reported.


METHODS
The long-term time and frequency domain measures of heart rate variability were analysed prospectively from 24-h Holter ECG recordings in 25 patients (39 +/- 8 years) with unexplained cerebral infarction, and in 25 age-, sex- and cigarette-smoking-matched healthy control subjects. The day following the Holter ECG recordings, 9 +/- 4 months (mean) after the stroke, stroke patients underwent an electrophysiological study in order to analyse the electrical characteristics of their right atria and also to determine their vulnerability to atrial fibrillation. The correlations between autonomic tone parameters and electrophysiological findings were therefore assessed with linear regression analyses.


RESULTS
All the measured components of heart rate variability either in time (SDNN, pNN50, SDANN/5, rMSSD) or frequency domains (total power, low-frequency, high-frequency power, low-frequency/high-frequency power ratio) were similar between stroke patients and controls. During electrophysiological study, atrial fibrillation was induced in 80% of stroke patients. Among these patients, atrial refractory periods were significantly shorter, local electrograms were longer, and latent atrial vulnerability index was markedly decreased when compared with patients having no inducible atrial fibrillation. Concerning heart rate variability analysis, no difference was found between patients with induced atrial fibrillation when compared with a matched subgroup of healthy control subjects. Furthermore, there was no statistically linear correlation between any of the measured autonomic tone parameters and any of the discovered atrial vulnerability markers.


CONCLUSIONS
The long-term autonomic tone parameters of young patients presenting with a history of unexplained cerebral infarction are similar to those of healthy control subjects and are not correlated with atrial vulnerability parameters or atrial fibrillation inducibility.