Antiphospholipid syndrome (APS) is a systemic autoimmune disorder in which the patient’s immune system makes antibodies (antiphospholipid antibodies [aPL]) that increase the risk of blood clots (thickened blood) and pregnancy complications.
Catastrophic APS, sometimes referred to as, CAPS, is the most severe form of APS and is very rare. It is defined as APS in which multiple blood clots in small, medium, and large blood vessels occur over a short period (usually within a week.)
Catastrophic APS occurs in less than one percent of APS patients. 
The international web-based catastrophic APS registry, which is based on published catastrophic APS case reports, currently includes 282 patients. 
It is not well known why the majority of APS patients develop single medium-to-large vessel clots, and only a few develop life-threatening rapidly progressive widespread clotting (catastrophic APS).
Nevertheless, the currently accepted hypothesis is that catastrophic APS occurs in genetically susceptible individuals in response to a “trigger” such as trauma, surgery, or infections (this is seen in about 50-60% of cases). 
Multiple blood clots can result in infarction (lack of oxygen in tissues) and failure of different organs, leading to “multiple organ dysfunction,” a life-threatening condition requiring intensive care unit (ICU) management. Although any organ can be involved in catastrophic APS, the most frequently affected organs are the kidneys, lungs, brain, skin, and heart.
In addition, patients can develop clots in unusual locations, such as the esophagus or ovaries, and may develop blood cell abnormalities such as low platelet counts (which can increase the risk of bleeding).
A patient is diagnosed with "definite" catastrophic APS when he/she fulfills all of the following criteria:
If a patient fulfills only three of the four criteria above, "probable" catastrophic APS is diagnosed.
Although early diagnosis of "definite" or "probable" catastrophic APS is very important for improved outcomes, the diagnosis can be challenging because: 
Because catastrophic APS is so rare, it is not easy to design a clinical trial to study whether any given medication is an effective treatment. Current treatment recommendations are based on an analysis of published catastrophic APS cases  and have three clear goals:
If catastrophic APS is suspected, aggressive treatment should be started without delay. Commonly used medications in catastrophic APS, which are usually given in combination, include: 
Short Term: Analysis of the published catastrophic APS case reports shows that mortality from this condition has been decreasing since the year 2000. This is probably due to the increased recognition and early treatment of the disease. However, catastrophic APS remains a very serious life-threatening condition. In addition to the specific manifestations of catastrophic APS, patients may develop other complications during the acute period - such as infections or bleeding - which directly affect the prognosis.
Long Term: Based on one retrospective (looking back at collected data) study that analyzed long-term outcomes (up to six years) in catastrophic APS patients, approximately 70% of the patients who survived the initial catastrophic APS event and took warfarin (a blood thinner), remained free of blood clots. 
Following a catastrophic APS event, permanent damage may occur; the extent of this damage depends on the type and severity of the organs involved. After an acute event, catastrophic APS patients receive long term anticoagulation therapy. Patients should discuss the need for other medications with their physicians and follow important precautions to reduce the risk of a new clot.
The lack of prospective studies (those designed to follow a group of patients over time) due to the rarity of the disease, has encouraged the European Forum on Antiphospholipid Antibodies, coordinated by Dr. Ricard Cervera, to develop an international catastrophic APS registry. The purpose of this web-based registry is to organize all published case reports, as well as newly diagnosed catastrophic APS cases, from all over the world. The registry currently includes the clinical, laboratory, and treatment data of 282 patients.
Genetics of Thrombotic Storm is another multicenter study, which aims to identify the genetic characteristics of patients with Thrombotic Storm syndromes (diseases in which patients develop multiple blood clots), including catastrophic APS. 
Learn more about the University of Miami Miller School of Medicine's Thrombotic Storm study.
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