Determinants of Exercise Intolerance in Postural Orthostatic Tachycardia Syndrome: A Systematic Review

Context: Postural orthostatic tachycardia syndrome (POTS) is characterized by increased heart rate (HR) with standing and is associated with dizziness, palpitations, and exercise intolerance, with poorly understood mechanisms. Objective: To review the literature on cardiorespiratory fitness in POTS, and explore possible determinants of exercise intolerance. Design: Systematic review of studies assessing exercise capacity in POTS. Eligibility Criteria: ) measures) in patients with established POTS using standard criteria. Study Selection: was measured in 15 studies and exercise hemodynamics (stroke volume (SV), cardiac output) was measured in 10 studies. Main Outcome Measures: , gas exchange parameters, and hemodynamics (i.e., HR, SV, cardiac output). Results: . Conclusion: Patients with POTS reach peak HR faster. Increased HR accompanies reduced SV, but cardiac output is generally maintained or increased, making it unlikely to cause symptoms. Reducing HR may improve exercise capacity in POTS by delaying peak HR and reducing symptoms.