<prompt> A 50 year old breast cancer patient presents with breathlessness. What does the ECG show?Normal tracingAV dissociationElectrical AlternansElectromechanical dissociation  <response>: HR is about 150min with variation in electrical axis due to fluctuation in amplitude of QRS complex on beat to beat variation. Malignancies like breast cancer and lung cancer can metastasize to the hea leading to cardiac tamponade. 