Pulmonary Hypertension in Pulmonary Langerhans Cell Histiocytosis: prevalence and the role of Cardiopulmonary Exercise Testing and echocardiogram in predicting it

Pulmonary Langerhans Cell Histiocytosis (PLCH) is often associated with pulmonary hypertension (PH). But the prevalence of PH in different severities of PLCH isn’t completely defined. Findings in Cardiopulmonary Exercise Testing (CPET) and echocardiogram may predict PH. Objectives: to evaluate the prevalence of PH in PLCH and the role of CPET and echocardiogram in predicting PH. Methods: Thirty-five patients (32% men, 47 ± 11 years) underwent CPET on treadmill, echocardiogram and lung function tests. Patients with tricuspid regurgitation velocity (TRV) ≥ 2,5 m/s and/or indirect signs of PH and/or DLCO Results: Peak oxygen consumption (VO2) was 73 ± 19 %predicted, reduced in 70% of cases. Oxygen pulse was 85 ± 18 %predicted, PetCO2 at anaerobic threshold was 34 ± 6, and VE/VCO2 slope was 31 ± 10. Ventilatory and cardiocirculatory limitations, CPET suggestive of PH and dynamic hyperinflation were identified in 58%, 41%, 33% and 68%, respectively. TRV was 2.9 (2.4 – 3.1) m/s and DLCO was 56 ± 21 %predicted. Twenty-one (60%) patients met criteria for RHC and 18 underwent it. The prevalence of PH was 41% (85% pre- capillary). The mPAP was 32 ± 12 mmHg and was associated with VO2 (r = - 0.54, p = 0.02), Oxygen pulse (r = - 0.55, p = 0.02); TRV (r = 0.69, p = 0.004), and DLCO (r = - 0.56, p = 0.01). However, there wasn’t association with PetCO2 or VE/VCO2. Conclusion: The prevalence of PH in PLCH was 41%, mainly pre- capillary. Classical CPET variables didn’t predict PH, possibly because of multifactorial involvement and a high prevalence of ventilatory limitation.