Chronic obstructive pulmonary disease (COPD) and ischemic heart disease (IHD) are common causes of mortality worldwide, with shared risk factors. COPD continues to be largely underdiagnosed and undertreated, especially in patients with IHD.

To investigate the prevalence of COPD in smokers with confirmed IHD and to compare IHD characteristics between COPD patients and those without COPD.

It was a cross-sectional study, conducted between August and December 2017, including patients over 40 years of age, current or former smokers, with stable and confirmed IHD. Spirometry was undertaken for all participants, and COPD was defined according to GOLD criteria.

A total of 122 patients, with mean age of 59.3 years and mean pack-year of 52.3, were enrolled. Spirometry was normal in 63.2% of patients and airflow limitation was the most frequent ventilatory disorder (20.5%). COPD was diagnosed in 19.7% of patients. Of the 24 COPD patients, 17 (70.8%) were previously undiagnosed. Airflow limitation severity in COPD patients was classified mild, moderate, severe and very severe in 25%, 62.5%, 8.3% and 4.2% of patients. Comparison between COPD patients and non-COPD patients showed that comorbidities, respiratory symptoms, chest x-ray abnormalities, life-threatening lesions, three vessel disease, pulmonary hypertension and right ventricle dysfunction were significantly more frequent in COPD patients.

There was a high prevalence of COPD among smoking patients with IHD, and most were undiagnosed despite being symptomatic. Smokers with IHD, especially if having respiratory symptoms, radiological or ultrasound abnormalities or life-threatening coronary lesions should be evaluated for airflow limitation.