Iron Deficiency in COPD Associates with Increased Pulmonary Artery Pressure Estimated by Echocardiography

Abstract

Objectives: Iron deficiency (ID) might augment chronic pulmonary hypertension in chronic obstructive pulmonary disease (COPD). This observational study investigates the association between ID and systolic pulmonary artery pressure estimated by echocardiography in non-anaemic COPD outpatients.

Methods: Non-anaemic COPD patients (GOLD II-IV) with no history of cardiovascular disease were recruited from outpatient clinics. Iron deficiency was defined as ferritin<100μg/L. Pulmonary artery pressure was estimated from the tricuspid regurgitation maximum velocity (TR V_max). Tricuspid regurgitation V_max indicative of pulmonary hypertension was considered present for values ≥ 2.9 m/s.

Results: In a total of 75 included patients, 31 (41%) had ID. These patients had a significantly higher TR V_max (3.02 vs. 2.77 m/s, p=0.01) and lower diffusion capacity of carbon monoxide (40% vs. 50% of predicted, p<0.01), though similar in age, sex, pack years, FEV₁ and high-sensitive CRP (p>0.05). Ferritin inversely correlated with TR V_max in ID patients (-0.37 (p=0.04)). The prevalence of TR V_max ≥ 2.9 m/s was twice as high in patients with ID (58% vs. 29%) and odds ratio of pulmonary hypertension in ID (compared to no ID) was 3.3 (95% CI 1.3-8.6, p=0.015).

Conclusion: Iron deficiency in non-anaemic COPD patients was associated with a modest increase in systolic pulmonary artery pressure and limitation of diffusion capacity.

Keywords: Chronic obstructive pulmonary disease; Echocardiography; Ferritin; Iron deficiency; Pulmonary hypertension; Systolic pulmonary artery pressure.