Increased P wave dispersion: a new finding in patients with syndrome X.

The present clinical study was undertaken in patients with syndrome X, namely angina with normal coronary arteries, to investigate the presence of increased P wave dispersion by comparing patients with coronary artery disease (CAD) and healthy control subjects. Three groups were studied - group A, 21 patients (48 6 years) with syndrome X; group B, 16 patients (56 9 years) with CAD; and group C, 16 healthy subjects (49 8 years). Patients with CAD were older than those in groups A and C (P=0.005 and P=0.035, respectively). All groups demonstrated similar PQ, QRS and RR intervals. Group B had a lower minimum P wave duration than group C (P=0.05). P wave dispersion in group A was found to be higher than that in groups B and C (P=0.018 and P=0.0001, respectively). Patients with syndrome X demonstrated increased P wave dispersion compared to patients with CAD and healthy subjects. High sympathetic tone or autonomic imbalance observed in patients with syndrome X may affect intra-atrial and interatrial conduction times, and leave them prone to develop atrial arrhythmias.