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Platelet reactivity in response to mental stress in syndrome X and in stable or unstable coronary artery disease.

Sestito A, Maccallini A, Sgueglia GA, Infusino F, Larosa C, Aurigemma C, Crea F, Lanza GA

Istituto di Cardiologia, Università Cattolica del S. Cuore, L.go A. Gemelli, 8 00168-Roma, Italy.

INTRODUCTION: Previous studies showed differences in platelet reactivity in response to exercise in patients with syndrome X (SX) and those with obstructive coronary artery disease (CAD). In this study, we investigated whether similar differences could be detectable in response to a mental stressful stimulus. MATERIALS AND METHODS: We studied 30 SX patients (60+/-8 years, 8 men), 20 patients with stable angina and angiographically documented CAD (SA, 66+/-8 years, 14 men), and 11 patients with unstable angina (UA, 67+/-8 years, 6 men). A control group of 22 healthy controls (50+/-7 years, 5 men) was also studied. All subjects underwent a mathematical mental stress test (MST) consisting of rapid consecutive subtractions of number 7 for a period of 5 min. A venous blood sample was collected at baseline and immediately after MST. Platelet reactivity was measured on flowing blood as time necessary to occlude a ring coated with collagen-adenosine diphosphate (ADP; closure time, CT), using the platelet function analyzer (PFA-100) system. RESULTS: At rest, CT was lower in UA patients (87+/-19 s) compared to controls (109+/-24 s, p=0.02) and SA patients (105+/-37 s, p=0.055), and also tended to be lower in SX patients (96+/-18 s) compared to controls (p=0.07). The CT response to MST differed significantly among groups (p=0.0009). At peak MST, CT did not change in controls (110+/-27 s, p=0.88), whereas it decreased in SA patients (96+/-29 s, p=0.003) and tended to decrease in UA patients (82+/-15 s, p=0.25). In contrast, a significant increase in CT with MST was shown in SX patients (103+/-21 s, p=0.007). CONCLUSIONS: Platelet reactivity is increased by MST in patients with CAD, whereas it paradoxically decreases in SX patients, which may constitute a protective effect against stress-induced events in these patients.

Published 26 April 2005 in Thromb Res, 116(1): 25-31.
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