ROLE OF ABNORMAL PAIN SENSITIVITY AND BEHAVIORAL-FACTORS IN DETERMINING CHEST PAIN IN SYNDROME-X

Objectives. We sought to investigate whether patients with syndrome X have an abnormal perception of cardiac pain, Background. Previous stud ies have reported an increased sensitivity to potentially painful card iac stimuli in patients with syndrome; X. However, it is not clear whe ther this increase is due to an increased perception of pain or to an enhanced tendency to complain, Methods. We assessed cardiac sensitivit y to pain in 16 patients with syndrome Ii and 15 control subjects by p erforming right atrial and ventricular pacing with increasing stimulus intensity (1 to 10 mA) at a rate 5 to 10 beats higher than the patien t's heart rate, False and true pacing were performed in random sequenc e, with both patients and investigators having no knowledge of the typ e of stimulation being administered, Results. No control subject had p acing-induced pain; con conversely, 8 patients with syndrome X reporte d angina during atrial pacing (50%, p < 0.01) and 15 during ventricula r pacing (94%, p < 0.001), During atrial stimulation, both true and fa lse pacing caused chest pain in a similar proportion of patients (50% vs, 63%, p = 0.61), whereas during ventricular stimulation, true pacin g caused chest pain in a higher proportion of patients (94% vs, 50%, p < 0.05), Pain threshold and severity of pain (1 to 10 scale) were sim ilar during true and false atrial pacing, whereas true ventricular pac ing resulted in a lower pain threshold (mean +/- SD 3.7 +/- 3.0 vs, 7. 9 +/- 2.8 mA, p < 0.001) and a higher level of pain severity (7.3 +/- 2.7 vs, 3.1 +/- 3.5, p < 0.001) than did false pacing, Conclusions. Pa tients with syndrome X frequently reported chest pain even in the abse nce of cardiac stimulation, Yet, in addition to this increased tendenc y to complain, they also exhibited a selective enhancement of ventricu lar painful sensitivity to electrical stimulation. (C) 1998 by the Ame rican College of Cardiology.