Objective To address the relationship between low antiplatelet response of clopidogrel and Obstructive Sleep Apnea Syndrome (OSAS) in patients with unstable angina pectoris.

Methods Total of 112 patients hospitalised with unstable angina pectoris from February 2008 to December 2009 were enrolled in this randomised consecutive study. All patients accepted routine treatment including clopidogrel, aspirin, low molecular weight heparin daily. Platelet aggregation (PAR) parameters were measured on samples obtained at baseline and 2^nd, 4^th, 6^th day. All patients were examined for the presence of sleep-disordered breath into 4 quartiles by ApneaLink. The concentration serum adrenaline and norepinephrine were measured in the morning at 6 a.m. after the sleep study.

Result There were no significant differences in the baseline data in all 4 quartiles. However, there was a significant differences in the number of diabetes patients in the first quartibesity, heale (p=0.0038) compared with other quartiles. At day 2 PAR were inhibited to 63.91% of baseline (p<0.01) and 88.38% (p>0.05) of baselinctively, in the first quartile. At each of these time points, platelet activity was significantly higher than in patients in other quartiles. At day 6 platelet aggregation were reduced to 32.37%, and 29.75% of baseline respectively in group 2 through 4 (p<0.01 for all). PAR was reduced significantly in patients in the second through fourth quartiles at day 6, but, it showed a lower reduction in the first quartile (p>0.05). Compared with that in thebidity of OSAS in the second and third were 25.0% and 14.3% (p<0.05), only 3.6% in the fourth group (p<0.01). Meanwhile, the concentratio first group (60.7%), the mor n of serum adrenaline and nine were higher in the first quartile than others (p<0.05).

Conclusion OSAS is aicator of low clopidogrel response in unstable angina patients, and higher concentration of epinephrine and norepinephrine in OSAS pa reliable ind tients plaorepinephry a more important role in this situation.