US Patent 7974687 Methods and systems for enhanced arrhythmia discrimination

Embodiments of the present invention are for use with implantable cardiac devices that discriminate between ventricular tachycardia (VT) and supraventricular tachyarrhythmia (SVT). Discrimination between VT and SVT can be based on: a detected absence, presence or degree of T-wave alternans leading up to the onset of a detected tachycardia; a detected absence, presence or degree of T-wave variability leading up to the onset of the detected tachycardia; and/or a detected cardiac electrical stability leading up to the onset of the detected tachycardia.