<prompt> Electric alternans is seen inCardiac tamponadeRestrictive cardiomyopathyConstrictive pericarditisRight ventricular infract  <response>: Rrf Harrison 19 th ed pg 1573 There may be reduction in ampli- tude of the QRS complexes, and electrical alternans of the P, QRS, or T waves should raise the suspicion of cardiac tamponade . the features that distinguish acute cardiac tampon- ade from constrictive pericarditis. 