Shortness of breath (SOB) is a common symptom referral for dobutamine stress echocardiography (DSE). Patients with SOB and a normal DSE have worse long-term outcome than the general population. This suggests multiple aetiologies are involved. The purpose of this study was to assess the prevalence and clinical significance of undiagnosed COPD amongst patients referred for a DSE with SOB.
We prospectively studied 114 patients referred for DSE with SOB without prior evidence of lung disease (mean age 64.9 ± 18.5 years, 60 male). Respiratory function testing using spirometry was performed on all patients on the day of their DSE. The study end-points were cardiac events and total mortality.
Respiratory function testing and DSE was performed in all patients and COPD was highly prevalent (n = 93). Multivariate Cox regression analysis was used to estimate the effect of dyspnoea on non-fatal cardiac events (NFCE) and all-cause mortality. Over a mean follow-up of 4.5 ± 2.6 years, the composite end-point of NFCE and all-cause mortality occurred in 62.7% and 16.7% patients, respectively. COPD (HR 1.27; 95% CI 1.17–1.93), previous myocardial infarction (HR 1.84; 95% CI 1.06–3.2), myocardial ischaemia (HR 2.56; 95% CI 1.48–4.43), peak wall motion score index (HR 4.66; 95% CI 2.26–9.6), and mitral E/E’ (HR 1.21; 95% CI 1.1–1.33) were significantly associated with a NFCE. Myocardial ischaemia (HR 4.43; 95% CI 1.24–15.81) was the only independent predictor of all-cause mortality.
Undiagnosed COPD is highly prevalent and independently associated with worse outcome amongst patients with SOB referred for DSE. Symptom presentation is therefore an important consideration when interpreting DSE results.