We aimed to assess whether chronic obstructive pulmonary disease (COPD) is associated with expansion of the myocardial extracellular volume (ECV) using T1 measurements.Adult COPD patients Global Initiative for Chronic Obstructive Lung Disease [GOLD] stage 2 or higher and free of known cardiovascular disease were recruited. All study patients underwent measures of pulmonary function, 6-minute walk test, serum measures of inflammation, overnight polysomnography, and a contrast cardiac magnetic resonance study.Eight patients with COPD were compared with 8 healthy control subjects. The mean predicted forced expiratory volume at 1 second of COPD subjects was 68%. Compared with control subjects, patients had normal left ventricular (LV) and right ventricular size, mass, and function. However, compared with control subjects, the LV remodelling index (median, 0.87; interquartile range [IQR], 0.71-1.14; vs median, 0.62; IQR, 0.60-0.77; P ¼ 0.03) and active left atrial emptying fraction was increased (median, 46; IQR, 41-49; vs median, 38; IQR, 33-43; P ¼ 0.005), and passive left atrial emptying fraction was reduced (median, 24; IQR, 20-30; vs median, 44; IQR, 31-51; P ¼ 0.007). The ECV was increased in patients with COPD (median, 0.32; IQR, 0.05; vs median, 0.27; IQR, 0.05; P = 0.001). The ECV showed a strong positive association with LV remodelling (r = 0.72; P = 0.04) and an inverse association with the 6-minute walk duration (r = -0.79; P = 0.02) and passive left atrial emptying fraction (r = -0.68; P = 0.003).Expansion of the ECV, suggestive of diffuse myocardial fibrosis, is present in COPD and is associated with LV remodelling, and reduced left atrial function and exercise capacity.