Detection of chronic obstructive pulmonary disease and frequency of cardiopulmonary events in patients with a significant smoking history hospitalised for acute myocardial infarction

Abstract Background Smoking is a major risk factor for chronic obstructive pulmonary disease (COPD) and also myocardial infarction (MI). Patients with COPD are more likely to have MI than those without and adequately treating COPD might improve cardiovascular outcomes. Reliable diagnosis is important for appropriate treatment. Prevalence of COPD in those hospitalised for MI has not been accurately established. Blood eosinophil count is an important guide to the benefit of inhaled corticosteroid (ICS) treatment in COPD. We aimed to accurately characterise lung function, symptom burden, eosinophil count and cardiopulmonary events in those with a significant smoking history hospitalised for acute MI. Methods Participants (n=216) with a smoking history of ≥10 pack-years currently hospitalised for acute MI were recruited at a single UK centre. Microspirometry and completion of the COPD Assessment Test (CAT) questionnaire were performed at enrolment. Presence and severity of COPD was graded using the Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification. A high burden of COPD symptoms was defined as a CAT score of >10. Repeat CAT and assessment for relevant cardiopulmonary events was undertaken at 3 months and 1 year after enrolment. Results In the enrolled cohort, median age was 60 years (IQR 53-67), 26% were female, 57% were current smokers and median pack-year history was 32 (23-45). 41 of 216 (19 %, [95% CI 14-25]) had evidence of COPD, defined as FEV1/FEV6 <0.7 on best-attempt microspirometry, with 39 (95%) being GOLD2 or greater. Of the 41 with detected COPD, only 15 (37%, [22-53]) had a prior diagnosis. In those with evidence of COPD, a high burden of COPD symptoms was present in 63% of participants at enrolment, 40% at 3 months and 45% at 1 year. 20% [9-35] were receiving inhaled corticosteroids at enrolment. 63% [47-78] had eosinophil count ≥100 cells/mm3 and 17% [7-32] ≥300 cells/mm3. Among those with detected COPD, after 1 year 19.5% (95% CI 9-35%) had suffered a respiratory illness requiring prescription of medication, which was numerically but not statistically significantly higher than those without detected COPD (14.3% [10-20%]). In the COPD cohort, death, infection requiring hospitalisation, MI or unplanned coronary revascularisation, and bleeding requiring hospitalisation each occurred on two occasions (4.9%). Conclusions Based on these data, the prevalence of microspirometry-diagnosed COPD of any severity in patients with significant smoking history hospitalised for MI is around 19%. There is a high rate of undiagnosed and untreated disease, a significant burden of symptoms, including during convalescence, and around a 20% incidence of respiratory illness requiring medical treatment at 1 year. Gathering accurate data from this group is helpful in planning research and service improvement. Increasing detection of COPD in patients with MI would lead to improved cardiopulmonary outcomes.