Arousal index as a marker of carotid artery atherosclerosis in patients with obstructive sleep apnea syndrome

PurposeIt was shown in a previous cohort study that men with internal carotid artery (ICA) plaque, defined as focal wall thickness of 1.5mm, had a threefold higher risk of stroke than those without plaque. We examined the relationship between arousal indices and sleep stages in patients with obstructive sleep apnea syndrome (OSAS) and carotid atherosclerosis.MethodsCarotid atherosclerosis severity was evaluated using the maximal carotid wall intima-media thickness of the ICA (ICA-maxIMT) and plaque in 83 patients with OSAS.ResultsThe ICA-maxIMT values were positively correlated with the apnea hypopnea index (AHI) (=0.294, P=0.007), arousal index (=0.289, P=0.008), oxygen desaturation index (=0.298, P=0.006), percentage of visually scored total sleep time spent in nocturnal oxygen saturation <90% (SpO(2) <90%) (=0.246, P=0.025), and the percentage of visually scored total sleep time spent in non-REM sleep stage 1 (=0.326, P=0.003) and were negatively correlated with the percentage of visually scored total sleep time spent in non-REM sleep stages 2 and 3. Arousal index, diabetes mellitus, and age were found to be independent predictors of ICA plaque presence (OR 1.052, P=0.003; OR 8.705, P=0.026; OR 1.064, P=0.023, respectively).ConclusionsSeveral PSG variables that are indicative of sleep fragmentation, sleep disordered breathing, and poor sleep quality correlated with the occurrence of atherosclerosis, but total arousal index was the only independent predictive factor.