Intermittent Noninfarction Q Waves: A Finding Suggestive of Latent Preexcitation

Objective To describe 3 patients who presented with chest pain and intermittent Q waves on the electrocardiogram (ECG) and were subsequently found to have latent preexcitation. Patients and Methods During a span of 8 years, 3 patients were evaluated because of atypical chest pain and pathologic Q waves in the inferior leads; in all 3 patients, the Q waves were intermittent. No patient had a history of arrhythmia or had Wolff-Parkinson-White pattern on the ECG. Diagnostic and therapeutic interventions for suspected myocardial infarction included cardiac catheterization in 2 patients, intravenous thrombolytic therapy in 1 patient, and heparin in 2 patients. Ischemic heart disease was excluded in all. Patients underwent pharmacological testing and/or electrophysiologic study for suspected preexcitation. Results Despite the absence of ECG markers of preexcitation, the presence of a latent accessory atrioventricular connection was confirmed in each patient by pharmacological or electrophysiologic studies. Conclusion In patients who present with intermittent noninfarction Q waves, the most likely diagnosis is latent preexcitation. Clinicians need to be educated about this clinical diagnosis and encouraged to pursue confirmatory testing. Such patients should be informed about the nature and importance of their electrocardiographic abnormality.