Inappropriate Sinus Tachycardia (IST) is an uncommon type of cardiac arrhythmia, within the category of supraventricular tachycardia (SVT). The mechanism and primary etiology of Inappropriate sinus tachycardia has not been fully elucidated. The mechanism of the arrhythmia primarily involves the sinus node and peri-nodal tissue and does not require the AV node for maintenance. Treatments in the form of pharmacological therapy or catheter ablation are available, although it is currently difficult to treat successfully.