Wolf-Parkinson-White alternans diagnosis unveiled by adenosine stress test.

The case of a 41-year-old woman who presented to her primary care physician with atypical chest pain was reported. An electrocardiogram (ECG) was performed in his office and the patient was told she had left bundle-branch block and an old infarct. The patient was very concerned and referred to cardiology for further evaluation/testing. An ECG at the cardiologist's office was normal. The cardiologist however suspected the ECG performed at the primary care physician office to be preexcitation (Wolf-Parkinson-White). During an adenosine nuclear stress test, intermittent preexcited beats occurred transiently to confirm the diagnosis of Wolf-Parkinson-White. Wolf-Parkinson-White can mimic multiple other ECG changes including a pseudoinfarct pattern and hence be misleading. The figure of the unique ECG, during the adenosine stress test, of intermittent preexcited (preexcitation alternans) complexes is included.