Observational case series describing features of cardiopulmonary exercise testing in Postural Tachycardia Syndrome (PoTS).

Postural Tachycardia Syndrome (PoTS) is a chronic condition often affecting multiple systems with varied presenting symptoms. Diagnosis is made by demonstrating cardiovascular criteria on standing along with clinical assessment. Cardiopulmonary exercise testing has been used to demonstrate and characterise the physiological response to exercise and the severity of the syndrome. Previous studies on exercise testing in these patients have focussed on cardiovascular changes alone. This series characterises the integrated cardiac and respiratory response to exercise seen with cardiopulmonary exercise testing. Our main findings show that peak oxygen uptake, work done and peak heart rate are significantly reduced from their respective predicted values in PoTS patients. However, despite this, most patients demonstrated a normal exercise capacity. Features of ventilatory inefficiency were also seen which suggest exercise capacity in these patients may be limited more by impaired ventilatory control such as dysfunctional breathing during exercise rather than by cardiovascular issues.