title: QT-interval variability and/or T-Wave alternans.
authors.forename: John E
authors.initials: JE
authors.lastname: Madias
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000628:therapy*; D017147:Defibrillators, Implantable; D004562:Electrocardiography / Q000379:methods*; D015444:Exercise; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012146:Rest; D012307:Risk Factors; D012815:Signal Processing, Computer-Assisted; D016277:Ventricular Function, Left / Q000502:physiology