Inorganic nitrate supplementation enhances functional capacity and lower-limb microvascular reactivity in patients with peripheral artery disease

Peripheral artery disease (PAD) is characterized by a reduced blood flow (BF) and an elevated blood pressure (pressor) response during lower extremity exercise. Although PAD is evident in the upper extremities, no studies have determined BF and pressor responses during upper extremity exercise in PAD. Emerging evidence suggests that inorganic nitrate supplementation may serve as an alternative dietary strategy to boost nitric oxide bioavailability, improving exercising BF and pressor responses during exercise. The present study investigated 1) BF and pressor responses to forearm exercise in patients with PAD ( n = 21) relative to healthy age-matched control subjects ( n = 16) and 2) whether 8 wk of NaNO3 supplementation influenced BF and pressor responses to forearm exercise in patients with PAD. Patients with moderate to severe PAD were randomly assigned to a NaNO3 (1 g/day, n = 13)-treated group or a placebo (microcrystalline cellulose, n = 8)-treated group. Brachial artery forearm BF (FBF; via Doppler) and blood pressure (via finger plethysmography) were measured during mild-intensity (~3.5-kg) and moderate-intensity (~7-kg) handgrip exercise. The absolute change (from baseline) in FBF was reduced (except in the 3.5-kg condition) and BP responses were increased in patients with PAD compared with healthy control subjects in 3.5- and 7-kg conditions (all P < 0.05). Plasma nitrate and nitrite were elevated, exercising (7-kg) ΔFBF was improved (from 141 ± 17 to 172 ± 20 ml/min), and mean arterial pressure response was reduced (from 13 ± 1 to 9 ± 1 mmHg, P < 0.05) in patients with PAD that received NaNO3 supplementation for 8 wk relative to those that received placebo. These results suggest that the BF limitation and exaggerated pressor response to moderate-intensity forearm exercise in patients with PAD are improved with 8 wk of NaNO3 supplementation. NEW & NOTEWORTHY Peripheral artery disease (PAD) results in an exaggerated pressor response and reduced blood flow during lower limb exercise; however, the effect of PAD in the upper limbs has remained unknown. These results suggest that 8 wk of inorganic nitrate supplementation improves the blood flow limitation and exaggerated pressor response to moderate-intensity forearm exercise in PAD.

Download Full-text

Abstract MP14: Proteinuria is Associated With a Greater Risk of Lower Limb Amputation in Patients With Peripheral Artery Disease

Circulation ◽

10.1161/circ.137.suppl_1.mp14 ◽

2018 ◽

Vol 137 (suppl_1) ◽

Author(s):

Jung-Im Shin ◽

Morgan Grams ◽

Josef Coresh ◽

Alex Chang ◽

Kunihiro Matsushita

Keyword(s):

Peripheral Artery Disease ◽

Lower Limb ◽

Proportional Hazards ◽

Cox Proportional Hazards ◽

Lower Limb Amputation ◽

Limb Amputation ◽

Antiplatelet Drug ◽

Peripheral Artery ◽

Increased Risk ◽

Artery Disease

Introduction: Proteinuria is shown to be associated with increased risk of peripheral artery disease (PAD). However, its association with the risk of lower limb amputation in patients with PAD is unknown. Hypothesis: We hypothesized that proteinuria is associated with the risk of amputation in patients with PAD in a graded fashion. Methods: We identified 3,388 PAD patients with data on urine dipstick proteinuria within two years prior to PAD diagnosis between 1997 and 2017 in the Geisinger Health System (mean age 69.7 years, 44.8% female, 97.4% non-Hispanic White, 57.8% diabetic). We quantified the association of proteinuria with the risk of amputation using Cox proportional hazards models, adjusting for demographics, calendar year, estimated glomerular filtration rate, HbA1c, comorbidities including diabetic retinopathy/neuropathy, and medication use (antiplatelet drug, statin, and renin-angiotensin system inhibitor). Results: There were 55.2% with negative dipstick proteinuria, 11.1% trace, 14.1% with 1+, and 19.5% with ≥2+. A total of 245 patients underwent amputations over a median follow-up of 3.4 years. Incidence rate of amputation was 1.15 per 100 person-years for dipstick negative, 1.47 for trace, 2.11 for 1+, and 3.78 for ≥2+. This dose-response relationship remained similar even after accounting for potential confounders (p-trend=0.015), with particularly evident association for ≥2+ of dipstick (an adjusted hazard ratio of 1.52 [95% confidence interval: 1.08-2.17, p=0.017) (Figure). When we added proteinuria to other covariates, the risk discrimination slightly improved (Δc-statistic 0.007 [0.001-0.014]). Conclusions: Higher proteinuria was associated with a greater risk of lower limb amputation among patients with newly diagnosed PAD. Our results suggest the importance of considering proteinuria in risk assessment of limb loss in PAD patients.

Download Full-text