Potential Biological and Physiological Determinants for Exercice in Patients With Polycythemia Vera

Polycythemia vera (PV) is a rare haematological disorder characterized by an excessive production of red blood cells, associated with the somatic JAK2 V617F mutation. Clinical manifestations are varied and often include exercise intolerance but the underlying mechanisms remain poorly understood. Physical activity is recommended in the management of chronic diseases, but it must be tailored to the physiological profile of the patient. A cardiopulmonary exercise test (CPET) is essential to ensure safety, detect possible contraindications, and assess maximal oxygen uptake (VO₂max), a key indicator of aerobic performance. This prospective, experimental, non-randomized study will include patients with PV followed at Lyon Sud University Hospital and for which a CPET is scheduled in their routine clinical follow-up. The primary objective is to compare VO₂max between two groups of patients: moderate (\<10%) versus marked (≥10%) extent of blood viscosity increase after the completion of the CPET. The main hypothesis is that a significant increase in blood viscosity during exercise (≥10%) is a major limiting factor in oxygen transport and leads to a reduced VO₂max, reflecting impaired exercise tolerance. Secondary analyses will focus on hemorheological parameters, tissue oxygenation, and cardiorespiratory and metabolic responses. The study aims to better understand the biological and physiological determinants of exercise intolerance in this population.

NCT Number	NCT07341048
Lead Sponsor	Hospices Civils de Lyon
Conditions	Polycythemia, Polycythemia Vera (PV)
Enrollment	54 participants
Start Date	2026-01
Primary Completion	2027-05 (estimated)
Study Completion	2027-05 (estimated)
Updated on ClinicalTrials.gov	2026-01-15