Hazard of Platelet Transfusion in Thrombotic Thrombocytopenic Purpura

Abstract

A patient with thrombotic thrombocytopenic purpura (TTP) showed for the first time catastrophic signs and symptoms of CNS involvement immediately after infusion of platelets. Postmortem examination revealed extensive deposits of platelet aggregates within the small blood vessels of the brain, whereas lesions elsewhere in the body consisted of platelets as well as fibrin and were associated with endothelial proliferation and microaneurysm formation. These findings are consistent with the view that the initial event in TTP may be platelet aggregation. The plasma of this patient contained platelet-aggregating activity. We conclude that platelet transfusions in patients with TTP may aggravate the disease process.

Platelet transfusions in platelet consumptive disorders are associated with arterial thrombosis and in-hospital mortality

“…[6][7][8] These published reports have held credibility due to: (1) biologic basis of the hypothesis; (2) identification of a close temporal relationship between platelet transfusions and adverse outcomes; and (3) autopsy analysis revealing that platelets were the principal component of the thrombotic lesion in TTP patients. [6][7][8]12 The generally accepted practice has been to restrict platelet transfusions only to life-threatening bleeds, and in fact, some clinical recommendations institute low-dose anti-platelet agents concurrent with platelet count recovery. [30][31][32] A systematic review and analysis of data from the Oklahoma TTP-HUS Registry could neither rule in nor rule out adverse outcomes from platelet transfusions and concluded that there was "uncertain evidence of harm."…”

“…[1][2][3][4][5] It has been hypothesized that platelet transfusions may potentially provoke fatal thrombotic events, [6][7][8][9][10] particularly arterial ones, in TTP and HIT. 10,11 In TTP, the principal histologic abnormality is proposed to be a "platelet microvascular thrombus."…”

von Willebrand factor‐cleaving protease activity in congenital thrombotic thrombocytopenic purpura

“…The potential hazards of increased plasma concentrations of factor VIII and VWF must also be considered. Platelet transfusions in TTP have been temporally associated with clinical deterioration (Harkness et al, 1981;Gordon et al, 1987), and gross elevations in circulating VWF concentrations, particularly if a concentrate contained high molecular weight multimers, could have a similar deleterious effect. However, should some factor VIII concentrates prove to be therapeutically beneficial, home treatment becomes possible with consequent improvements in quality of life.…”

Current understanding of the pathophysiology of thrombotic thrombocytopenic purpura

“…Because neither pronounced perivascular inflammation, obvious endothelial cell desquamation, nor subendothelial exposure have been demonstrated in TTP, it has been hypothesised that TTP might be a disease of primary platelet aggregation within the microvasculature. 6 In support of this, immunohistochemistry shows that thrombi formed in TTP contain abundant amounts of von Willebrand factor (vWF) and little fibrinogen or fibrin, in contrast to those found in disseminated intravascular coagulation (DIC), where the reverse is seen. 7 This has led to the hypothesis that vWF multimers, perhaps in conjunction with high shear stress, might promote platelet aggregation during episodes of TTP.…”