The catastrophic antiphospholipid syndrome, 1998. A review of the clinical features, possible pathogenesis and treatment.

A review of 50 patients who manifest features of the catastrophic antiphospholipid syndrome (CAPS) is presented. The clinical features comprise mainly organ involvement as opposed to large-vessel venous or arterial occlusions as is seen in patients with 'simple' antiphospholipid syndrome (APS), which makes the pathogenesis of this unusually rare complication perhaps somewhat different from that of patients with the APS. The mortality of the condition is 50%, most patients dying as a result of a combination of cardiac and respiratory failure. Fifteen patients (28%) suffered from disseminated intravascular coagulation (DIC) as well, which may have contributed to the multiorgan thrombotic microangiopathy characteristic of the CAPS. Although most patients were treated with high-dose i.v. steroids, heparin, cyclophosphamide and other modalities of therapy (such as i.v. globulin), plasmapheresis (advocated for TTP, a similar microangiopathic condition) seemed to offer some benefit (68% recovery). The systemic inflammatory response syndrome (SIRS) was responsible for some of the clinical manifestations such as adult respiratory distress syndrome (ARDS) seen in 15 patients. Pathogenesis of the CAPS seems dependent on a 'two-hit' or even 'three-hit' hypothesis in patients already suffering from a hypercoagulable state. Precipitating factors include infections, trauma (surgical), drug administration and warfarin withdrawal. A recent view that the multiple thrombotic lesions themselves may contribute to further thrombosis ('thrombotic storm') is also discussed.