Response to 35% CO2 in patients with chest pain and angiographically normal coronary arteries

Several interview studies have suggested that panic disorder (PD) exists in patients with angiographically normal coronary arteries (NCA). Interview studies require corroboration by other studies in order to validate them. The purpose of this study is to test whether response to the inhalation of 35% CO2 reliably discriminates between PD and non-panic disorder patients in this population.

Three groups were studied: six with NCA and PD, five with NCA and no PD, and ten in the control group. All subjects breathed room air, then 35% CO2 in a single-blind fashion. Each completed the Acute Panic Inventory (API) before and during the procedure.

The NCA-panic group scored significantly higher than the other two groups on the Acute Panic Inventory from baseline to post-inhalation.

Despite several methodological limitations including a relatively small number people in each cells, 35% CO2 was shown to trigger more intense responses in panic patients, thus helping to validate the interview findings.