Reduced EEG complexity in stable coronary artery disease: an evidence of covert brain dysfunction.

BACKGROUND

Accumulating evidence indicates that coronary heart disease (CHD) is frequently accompanied by cerebral injury. Non-linear electroencephalogram (EEG) analysis is an effective method for capturing abnormal EEG signal dynamics. This study characterized the complexity of EEG in CHD patients based on non-linear indices.

METHODS

Twenty-seven patients with CHD were enrolled, as well as an equal number of non-coronary controls. Five-minute, resting-state EEG recordings were obtained under standardized conditions. Non-linear dynamics were quantified using Lempel-Ziv complexity (LZC), permutation Lempel-Ziv complexity (PLZC), sample entropy (SampEn), and permutation entropy (PE). Between-group differences were assessed by independent-samples t-tests. Within the CHD cohort, Pearson correlations were calculated between each non-linear index and clinical variables-age, disease duration, left-ventricular ejection fraction (LVEF %), and number of affected coronary arteries.

RESULTS

Compared with controls, the CHD cohort exhibited significantly reduced LZCmean, LZCmidp, SampEn, PLZC, and PE at multiple electrodes distributed across the entire scalp. A representative finding showed that: at electrode T8, LZCmean was lower in CHD patients than in controls (0.73 ± 0.09 vs 0.79 ± 0.08; t = -2.683, p = 0.010). Age and disease duration were negatively correlated with several non-linear indices; for example, disease duration inversely predicted LZCmidp at FPz (r = -0.573, adjusted p = 0.004). LVEF% was positively associated with selected measures. No significant correlations were found between the number of affected coronary arteries and any EEG complexity metrics.

CONCLUSION

CHD patients demonstrated significantly lower total spectrum EEG complexity compared to non-CHD controls, offering novel electrophysiological evidence of central nervous system impairment in cardiovascular disease and suggesting potential functional brain alterations.