Abolition of Wolff-Parkinson-White pattern during episodes of angina.

A 70-year-old woman presented with unstable angina following a myocardial infarction. At cardiac catheterisation she had inferoapical dyskinesia, blocked right and circumflex arteries and an 80% stenosis of the left anterior descending artery. When free of angina, the ECG showed a Wolff-Parkinson-White (WPW) pattern consistent with a posterior free wall accessory pathway. However, during some episodes of angina at rest, she reverted to normal conduction and back again to the WPW pattern after the angina subsided with sublingual nitrate. The disappearance of the WPW pattern during angina can be explained by transient ischaemia blocking conduction in the accessory pathway.