Panic anxiety and hyperventilation in patients with chest pain: a controlled study.

We studied the relation between mood disorder and hyperventilation (hypocapnia) before and during exercise treadmill testing in 113 chest pain patients attending a cardiac clinic and 30 healthy controls. In most patients end-tidal PCO2 (PCO2) rose in the normal way on exercise but in a subset of 24 (21 per cent) there was no rise: these patients with initial hyperventilation had significantly higher anxiety scores than those with a normal exercise-induced rise in PCO2. Two of the 24 had ischaemic heart disease and 10 (42 per cent) complained of recent panic anxiety compared with 12 (13 per cent) of the 89 with normal rise in PCO2 (p less than 0.05). Rates of psychiatric morbidity were similar in patients with 'typical' and 'atypical' chest pain. Resting hypocapnia occurred more often in patients with panic anxiety than in either anxious or non-anxious patients without panic. Panic patients also reported more symptoms of breathlessness and hyperventilation-related complaints than those without panic. Our findings confirm the important association between panic and hyperventilation in patients with chest pain. Furthermore, patients with exercise-induced hyperventilation are more likely to have a psychiatric than a cardiac disorder. Early detection and treatment of these patients may reduce the potential morbidity associated with unnecessary invasive investigations.