Clinical Clues for the Current Diagnosis of Acute Lower Limb Ischemia: A Contemporary Case Series

Acute lower limb ischemia (ALI) is a limb and life-threatening condition whose treatment largely depends on the underlying cause. The clinical distinction between the main causes may have changed over the years because of changes in the epidemiology of this syndrome. The objective of this study was to determine the clinical pattern associated with the main causes of ALI in a contemporary series of cases.

We retrospectively reviewed all consecutive ALI cases admitted to a tertiary hospital between 2007 and 2019. ALI secondary to other conditions than embolism or NAT were excluded. The association between clinical variables and the ALI cause was assessed with multiple logistic regressions and the discriminative power of the resulting clinical predictive scores with the area under the ROC curve.

The study group included 243 patients (mean age 77.2 years; 52.7% male), of which 140 (57.6%) were caused by an arterial embolism and 103 (42.4%) by a NAT. Among these latter, 78 (75.7%) were related to an atherosclerotic NAT and 25 (24.3%) to a complicated popliteal aneurysm. Independent risk factors associated with embolism included atrial fibrillation (OR 10.26, 95% CI 5.1 - 20.67) or female gender (OR 5.44, 95% CI 2.76 - 10.71), but not the severity of the episode or the presence of contralateral pulses. Those related to a NAT included a previous symptomatic peripheral arterial disease (OR 2.68, 95% CI 1.35 - 5.35) and seeking consultation more than 24 hours after the beginning of symptoms (OR 2.57, 95% CI 1.32 - 5), but not a higher rate of other vascular risk factors. Among patients with NAT, previous intermittent claudication (OR 8.34, 95% CI 2.42 - 28.72) and >24 hs delay of arrival of the patient (OR 4.78, 95% CI 1.48 - 15.43) were more frequent among those related to an atherosclerotic NAT, whereas higher hemoglobin levels (OR 1.60, 95% CI 1.21 - 2.11) and non-significantly the history of tobacco smoking (OR 2.95, 95% CI 0.84 - 10.36) among those with a popliteal aneurysm-related NAT. The discriminative power of the two clinical models resulting from these predictive variables for differentiating embolism from NAT and atherosclerosis-related NAT from popliteal aneurysm-related NAT was excellent (0.86 and 0.85, respectively).

Certain clinical features appear to be no longer useful in the distinction between embolism and NAT, while others may help in the differential diagnosis between atherosclerotic and popliteal aneurysm-related NAT. Surgeons must be aware of possible changes in the presentation of ALI because time constraints are frequent and clinical data remain essential.