Cardiopulmonary exercise testing (CPET)
Burghard et al. in the Netherlands examined effects of iva in 7 pwCF heterozygous for the S1251N mutation (1.2% in Dutch population), over a median of 15 months22. Nutritional parameters changed, with BMI significantly increasing (19.9 kg to 21.2 kg, p=0.03), but BMI z-score, fat mass, and lean mass did not increase. Pulmonary function parameters changed with an increase in FEV1pp (81.7% to 97.7%, p=0.02) and a decrease in RV/TLC (residual volume/total lung capacity) (31.5% to 16.8%, p=0.02). No changes in resting energy expenditure were seen, but CPET indices improved, ppVO2peak (93.4% to 80.7%, p=0.01), ppVO2peak/kg (95.6% to 78.8%, p=0.001), and change in VO2 over work rate (10.7 to 8.5 mL/watt, p=0.01), while other indices had no significant change22. In a separate study, 11 adults performed constant load cycling, with assessment of dyspnea and leg discomfort23. No change in endurance time, exertional dyspnea or leg discomfort occurred after one-month of lum/iva, but those who experienced reduction in leg discomfort showed improved endurance time.