Increased Whole Blood Platelet Aggregation in Patients with Raynaud's Phenomenon with or without Systemic Sclerosis

Abstract

Platelet activation may have a pathophysiological role in Raynaud's phenomenon (RP). However, previous studies have shown conflicting results. This may be related to patient selection and the choice of platelet function assay. In this study, we have assessed platelet function of 30 patients with severe RP with (n = 14) or without (n = 16) systemic sclerosis (SSc), using a whole blood platelet aggregation (PA) assay. Raynaud's medication or other drugs which may affect PA were stopped at least 2 weeks previously. Spontaneous whole blood PA and that induced by 0.5 microM adenosine diphosphate and 0.6 and 1 microgram/ml collagen were significantly increased in both groups of patients when compared with controls. There were no significant differences in PA between the 2 groups of patients. Using a more physiological assay, patients with severe RP, whether or not associated with SSc, were shown to have abnormally increased platelet activity. Hyperactive platelets may further impede blood flow in RP.

Systemic sclerosis is an independent risk factor for increased coronary artery calcium deposition

“…Increased frequency of coronary artery calcification in SSc patients compared to controls has also recently been reported in a pilot study of smaller sample size (27), despite the similar or lower rate of CAD in SSc patients compared with controls demonstrated by some studies (13,15). Although myocardial insufficiency in SSc has been attributed to microvascular disease (28) and imbalanced hemostasis (29) in earlier studies, coronary atherosclerosis has been increasingly revealed by conventional coronary angiography in SSc patients (13,14), concomitant with the significantly improved survival of these patients over the past decades (30). Other macrovascular diseases, such as peripheral vascular disease, have also been frequently reported in SSc patients (31,32).…”

The evaluation of mean platelet volume levels in patients with primary and secondary Raynaud’s Phenomenon

“…In primary Raynaud and systemic sclerosis, increased platelet activation and aggregation has been reported [19]. In, patients with severe RP, whether or not associated with SSc, were shown to have abnormally increased platelet activity.…”

“…Progressive deficiency in vasodilatory capacity of the vessels is proposed as a mechanism of RP, particularly in systemic sclerosis. In addition, decreased fibrinolysis and enhanced coagulation pathways undoubtedly contribute to vascular dysfunction [19].…”

Blood Platelets and Systemic Sclerosis

“…The absence of endothelium abnormalities in the primary Raynaud's phenomenon is generally accepted, although limited morphological abnormalities have been described [199]. However, features of platelet activation are found in primary Raynaud's phenomenon [158,200,201] and platelet activation was proposed to play a role in its pathogenesis [135,202]. Therefore, events responsible for the Raynaud's phenomenon lead to platelet activation in the absence of EC damage, a possible argument to place platelet activation as a very early pathogenic event in the reciprocal activation dialogue between platelets and ECs.…”

“…Hyperaggregability Spontaneous (in whole blood) In response to agonists [126]; [131]; [154][155][156][157][158] Enhanced adhesion to collagen [159];…”