Finally, AHIFM and AHIDM were highly correlated. Moreover, freeze drying heart ventricles before calculation of AHI substantially improved statistical power to evaluate mean AHI between treatment groups, implying a methodological improvement.The former is likely because of the increase in range of AHI through freeze-drying. Herewith, regression analysis determined a value of 0.30 for AHIDM to be equivalent to the cut-off of value of 0.27 for AHIFM, in the assessment of onset of pulmonary
hypertension.