<prompt> Answer this question truthfullyCould you explain the meaning of wave alternans?  <response>: <reason> T-wave alternans predicts arrhythmia, sudden cardiac death, or cardiovascular or total mortality in these patient groups:Congenital heart disease Congestive heart failure Dilated cardiomyopathy Diabetes Ischemic and nonischemic cardiomyopathy Left ventricular dysfunction Long QT syndrome Myocardial ischemia and infarction Non-STEMI acute coronary syndrome Patients with ICDs during anger See also: Patients with acute coronary syndrome during percutaneous coronary intervention Patients with STEMI during percutaneous coronary intervention Vasospastic angina T-wave alternans is associated with ventricular arrhythmias in these patient groups:Brugada syndrome Coronary artery disease Medical therapyProarrhythmia including Amiodarone, Antibiotics, Cancer therapy agents Sleep apnea T-wave alternans has also been observed in these conditionsAlcoholic cardiomyopathy Epileptic seizure Hypocalcemia Hypokalemia Hypomagnesemia ICD shocks Myocardial scar Pulmonary embolism Quinidine Renal failure 