You are presented with a paragraph from a COVID-19 literature. Classify the topics of this piece of text by choosing from the following categories:

- Epidemic Forecasting: The content relates to predictions about the spread of COVID-19.
- Treatment: The paragraph discusses therapeutic methods or medication for COVID-19.
- Prevention: The content covers measures to prevent the spread of COVID-19.
- Mechanism: The paragraph explains the biological mechanisms of the virus.
- Case Report: The content is a report of a COVID-19 case.
- Transmission: The paragraph discusses how COVID-19 is transmitted.
- Diagnosis: The content is about diagnosing COVID-19 in individuals.

Your classification should be provided as an element within a JSON array. The array should be formatted with topics enclosed in double quotes and separated by commas, following the JSON format, for example: ["Topic1", "Topic2", ...]. Include all applicable topics within the array. Your output should be a valid JSON array, and no additional text should be included in your response.

Article:

Since the coronavirus pandemic set in in Spain in March 2020, a noteworthy increase in the incidence of acute limb ischemia (ALI) has been observed. It has been recently discovered that SARS-CoV 2 may lead to ALI secondary to arterial thrombosis. Elevation of D-dimer (DD) in patients with coronavirus infection (COVID-19) indicates that a hypercoagulable state causes acute arterial thrombosis. A remarkably high DD elevation has been reported to be a poor prognosis factor in COVID-19. The ways in which SARS-CoV 2 results in arterial thrombosis may be multiple. On the other hand, surgical revascularization for ALI is associated with poor outcomes in COVID-19 patients, probably in relation to hypercoagulability. Here, we describe two ALI cases in patients who required urgent surgical treatment for limb salvage and were positive for the novel coronavirus infection (COVID 19).
["Case Report"]