Anemia and elevated plasma proBNP levels have been identified as risk factors for airflow limitation in patients with heart failure. However, the role of these factors in airflow limitation in patients with ACS is not well established.

This study aimed to determine the prevalence of airflow limitation and investigate the association of anemia and plasma proBNP levels as risk predictors in patients with acute coronary syndrome (ACS).

All consecutive patients with a diagnosis of ACS, who accepted and were able to participate, underwent a spirometry test that was considered obstructive post-bronchodilation using the fixed ratio criterion (FEV1/FVC <0.7). Information on respiratory history symptoms, comorbidities, and potential risk factors of COPD were also collected. We used multivariable logistic regression with calculation of adjusted proportions for all analyses.

Of the 258 ACS patients who underwent spirometry, 75% had underdiagnosed COPD, with underdiagnosis rates of 82.4%, 78.9%, and 25.0% in those with mild, moderate, and severe airflow limitation, respectively. Airflow limitation was significantly associated with pack-years, anemia, and NT-proBNP levels >500 pg/mL (P<0.01). Performing spirometry in 31% of patients with risk factors detected 57% of undiagnosed airflow limitation cases, despite the condition being largely undiagnosed. Airflow limitation prevalence was 15.5% in this ACS cohort, and it was significantly associated with anemia and elevated NT-proBNP levels in addition to smoking history.

Our results suggest that patients with ACS and these risk factors should be evaluated for the presence of COPD