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


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.
Sestito
Alfonso
A
Istituto di Cardiologia, Università Cattolica del S. Cuore, L.go A. Gemelli, 8 00168-Roma, Italy.
Maccallini
Antonella
A
Sgueglia
Gregory Angelo
GA
Infusino
Fabio
F
Larosa
Claudio
C
Aurigemma
Cristina
C
Crea
Filippo
F
Lanza
Gaetano Antonio
GA
D000368:Aged; D000787:Angina Pectoris / Q000097:blood / Q000523:psychology; D003324:Coronary Artery Disease / Q000097:blood / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D017566:Microvascular Angina / Q000097:blood / Q000523:psychology*; D008875:Middle Aged; D015539:Platelet Activation; D010979:Platelet Function Tests; D013315:Stress, Psychological / Q000097:blood*