Carotid Artery Reactivity Predicts Events in Peripheral Arterial Disease Patients

Objective: Patients with peripheral arterial disease (PAD) have increased risk on future cerebro- and cardiovascular events. Our aim was to examine whether carotid artery reactivity (CAR; a novel, simple procedure to examine endothelial function) predicts cardiovascular events in PAD patients. Background: Increased risk for future cardiovascular events in PAD patients is likely related to endothelial dysfunction, highlighting the necessity for simple assessment of endothelial function. Methods: A total of 172 PAD patients (68 +/- 10 years, 67% male) underwent the CAR, which involves ultrasound measurement of carotid artery diameter during sympathetic stimulation produced by 90-second hand immersion in 4 degrees C ice-water (ie, cold pressor test). CAR-responses were dichotomized into carotid constriction or dilation. We recorded cardiac and cerebrovascular events, mortality, and clinical progression to percutaneous transluminal angioplasty or loss of patency during 12-month follow-up. Results: Eighty-two PAD patients demonstrated carotid constriction and 90 patients demonstrated dilation. PAD patients with carotid constriction showed more cardiovascular events compared to patients with dilation (Kaplan-Meier Log rank; P < 0.05). Cox proportional hazard models showed that patients with carotid constriction continued to show higher risk for cardiovascular events [hazard ratio: 4.1; 95% confidence interval (CI), 1.3-12.5] and clinical progression (hazard ratio: 2.0; 95% CI, 1.2-3.3), even after adjustment for other risk factors. Ankle brachial pressure index and carotid intima-medial thickness alone did not predict (cardiovascular) event or improve risk assessment beyond that provided by CAR. Conclusion: Carotid vasoconstriction identifies PAD patients with a 4-fold increased risk for future cardiovascular events and 2-fold increased risk for clinical deterioration. CAR provides a simple, novel strategy to predict cardiovascular events and progression in PAD patients.