We read with interest the article by Enriquez and colleagues1 in a recent issue of CHEST (September 2011) about the increased number of adverse events after percutaneous coronary intervention (PCI) in patients with COPD. Data from their study are consistent with those reported previously, indicating a higher incidence of adverse effects and mortality in patients with a previous diagnosis of COPD undergoing coronary catheterization for ischemic heart disease.2 However, diagnosis of COPD in both was based upon clinical criteria plus questionable criteria (COPD medication or a pre-bronchodilator (BD) FEV1 <75% predicted value) without full respiratory functional studies, while in the Konecny et al3 study, spirometry was available only in 60% of patients. In our opinion, this explains the observed low prevalence of COPD (Berger et al,2 4%; Enriquez et al,1 8%; and Konecny et al,3 13%), which is clearly lower than expected in this population (even in the general adult population). In contrast, the prevalence observed by Soriano et al4 in patients with ischemic heart disease confirmed by PCI and with full post-BD spirometry was 34% and, of note, with an underdiagnosis of 87%.1 Similarly, in a prospective study currently underway at our institution, spirometry within the prevalence of COPD was 20% in the first 72 patients with ischemic heart disease confirmed by PCI and with full post-BD, with an underdiagnosis of 72% (unpublished data, 2012). It seems plausible that the lack of a more accurate diagnosis can modify the results by Enriquez and colleagues1 to classifying as patients with COPD only those with more symptomatic and perhaps more severe disease. Given all prognostic and therapeutics implications, it should be advisable to conduct spirometry in patients with ischemic heart disease referred for PCI.