Original
There is no recorded history of Inappropriate Sinus Tachycardia. It is however, believed to have existed for many decades in patients who did not present with symptoms. If patients had presented to doctors with symptoms, then they may have been misdiagnosed as "Medically Unexplainable Symptoms".
It is only recently, within the last decade, that doctors have given a name to the condition and have classified it as a rare cardiac arrhythmia.