Twenty years ago physicians dusted off a phrase Rosen and Cryer1 employed a decade earlier in reference to a carefully studied hyperadrenergic patient, and used the term ‘idiopathic postural orthostatic tachycardia syndrome’ or ‘postural tachycardia syndrome’ (POTS) to describe symptomatic patients with excessive tachycardia on standing,2 thereby re-christening a number of older, poorly differentiated entities such as orthostatic intolerance,3 idiopathic hypovolaemia,4 effort syndrome, mitral valve prolapse syndrome, vasoregulatory asthenia and neurocirculatory asthenia. Defined by Phillip A Low, Ron Schondorf and their colleagues in clear and thoughtful terms,5 the postural tachycardia syndrome soon became a home for many poorly understood conditions presenting as orthostatic intolerance.

Bringing these together under the POTS rubric had a number of important consequences. By focussing on heart rate rather than blood pressure (which is usually not abnormal in POTS), it created a new benchmark which had not been the diagnostic focus in previous incarnations of these disorders. That led to increased recognition because many physicians and patients noticed the tachycardia and it became the organising principle in diagnosis. Large numbers of patients began to be diagnosed as having POTS. In recent years the number of such patients continues to grow, particularly in North America but also in Europe. Some estimates place the prevalence of POTS as high as 1 …