Critical and subcritical ischaemia.

OBJECTIVES: To stratify leg ischaemia into high and low risk groups with respect to outcome.
METHODS: An evaluation of 20 recent publications, reporting the results of 6118 patients with critical ischaemia. Low and high risk patient groups are identified by the definition of critical ischaemia. These groups are analysed with respect to outcome of the patient and limb. MAIN OUTCOME MEASURES: Major amputation and mortality.
RESULTS: From these data subcritical (rest pain and/or ankle pressure > 40 mmHg, n = 4089) and critical (tissue loss and/or ankle pressure < 40 mmHg, n = 2029) risk group of patients was identified. The 1, 3 and 5-year mortality is 26%, 44% and 56% with or without reconstruction. For patients in the low risk group, 27% did not lose their leg within the year if treated conservatively. For patients in the high risk group, amputation was required by 95% if treated conservatively, compared to 25% if treated with arterial reconstruction.
CONCLUSION: Reconstructive surgery should be viewed from the following, more realistic, perspective. For patients with rest pain (and/or ankle pressure > 40 mmHg), 100% cumulative patency is equivalent to 64% resolution of symptoms at 1 year, as the rest may have improved without treatment. For high risk patients (tissue loss and/or ankle pressure < 40 mmHg), 100% cumulative patency is equivalent to 93% limb salvage at 1 year. Future reports should identify these two groups separately, as the dominant difference between outcome studies is the proportion of subcritical patients in the study rather than better surgical or radiological techniques. This stratification also has an important bearing on pharmacotherapy trials.