Unexplained breathlessness and psychiatric morbidity in patients with normal and abnormal coronary arteries.

Of 99 patients with chest pain undergoing coronary arteriography, 31 had normal coronary arteries, 15 slight disease, and 53 significant coronary obstruction. 28 (61%) of the 46 with haemodynamically insignificant disease and 12 (23%) of the 53 with significant obstruction had psychiatric morbidity, assessed by standard interview. 37 patients had several respiratory symptoms and signs not attributable to organic disease, designated unexplained breathing disorder (UBD). UBD was found in 65% of the patients without and 13% of those with significant coronary disease; it was associated with psychiatric morbidity in the former but not in the latter group. Spirographic measurements of tidal volume and frequency were not helpful in detecting UBD but an end-tidal pCO2 below 30 mm Hg was highly suggestive. In the absence of significant coronary disease the associations of chest pain with psychiatric morbidity and UBD are striking. However, coronary disease and UBD are not mutually exclusive, and diagnostic difficulties can occur when they coexist.