Bilateral low systolic toe pressure and toe-brachial index are associated with long-term mortality in patients with peripheral artery disease

Abstract

ObjectiveBased on our previous reports, ipsilateral systolic toe pressure (STP) and toe-brachial index (TBI) have a strong association with midterm cardiovascular and overall mortality as well as with amputation-free survival in patients with symptomatic lower extremity peripheral artery disease (PAD). The effect of the often overlooked contralateral lower limb on patient outcome remains unknown. This study aimed to resolve the significance of contralateral STP (CL_STP) and contralateral TBI for long-term overall and cardiovascular mortality. MethodsThis is a retrospective cohort study of 727 consecutive patients with symptomatic lower extremity PAD. All patients admitted to the Department of Vascular Surgery at Turku University Hospital for digital subtraction angiography between January 2009 and August 2011 and for whom STP measurements were available were recruited and observed for up to 7 years. Dates and causes of death were collected from the national cause of death registry of Statistics Finland. ResultsIn the study cohort, STP was <30 mm Hg in 67 contralateral limbs and 227 ipsilateral limbs. CL_STP <30 mm Hg resulted in a 60-month estimated freedom from cardiovascular death and overall survival of 39% (standard deviation [SD], 0.57) and 25% (SD, 0.41), respectively, and contralateral TBI <0.25, of 45% (SD, 0.54) and 36% (SD, 0.54), respectively. Cumulative freedom from cardiovascular death and overall survival at 60 months for patients with ipsilateral STP <30 mm Hg varied by CL_STP as follows: CL_STP <30 mm Hg: 41% (SD, 0.58) and 25% (SD, 0.43); CL_STP of 30 to 49 mm Hg: 56% (SD, 0.49) and 44% (SD, 0.49); STP ≥50 mm Hg: 62% (SD, 0.52) and 47% (SD, 0.52), respectively. In Cox regression analysis, low STP or TBI of either extremity was associated with significant (P < .001) risk of death for cardiovascular or any reason. ConclusionsLow STP and TBI of both contralateral and ipsilateral lower extremities are associated with high cardiovascular and overall mortality in symptomatic PAD patients. Bilaterally low STP and TBI are associated with a particularly poor prognosis.