The ventilatory efficiency parameters outperform peak oxygen consumption in monitoring the therapy effects in patients with hypertrophic cardiomyopathy.

We sought the cardiopulmonary exercise testing (CPET) parameter that most accurately reflected therapeutic efficacy in patients with hypertrophic cardiomyopathy (HCM). Well-being questionnaire, N-terminal brain natriuretic peptide measurements, echocardiography, and CPET were performed in patients with symptomatic non-obstructive HCM during phase II, randomized, open-label multicentre study, before and after 16 weeks of traditional or sacubitril/valsartan treatment. Patients were followed 36 months after the initial CPET. Primary endpoints were changes in: 1) peak oxygen consumption (VO 2); 2) VO 2 at anaerobic threshold (AT); 3) oxygen pulse; 4) minute ventilation (VE)/carbon-dioxide (CO 2) production slope; 5) VE/VCO 2 at AT (VE/VCO 2 _AT); 6) VE/VCO 2 nadir; 7) VE/VCO 2 intercept; and 8) partial end-tidal pressure of carbon-dioxide (P ET CO 2) change during CPET. Of 115 screened patients, 61 (52 ± 14 years, 43 % women) were included. Within subject therapy effects were detected only by the VE/VCO 2 intercept and P ET CO 2 change, whereas the differences between medical regimens were detected by differences in VE/VCO 2 nadir and VE/VCO 2 _AT changes after the treatment. The best predictors of the change in well-being were left ventricular outflow tract maximal gradient and VE/VCO 2 intercept (B = 0.41,0.36; SE = 0.16,0.30; CI = 0.14–0.79, 0.15–1.14; p = 0.006,0.016, respectively). Adverse cardiac events were best predicted by the initial VE/VCO 2 nadir. Ventilatory efficiency parameters outperform peak VO 2 in gauging therapy effects in patients with HCM. [ABSTRACT FROM AUTHOR]