Correlation between mPAP and sPAP
Our study results demonstrated the strong correlation between mPAP measured by RHC and post-exercise sPAP estimated using echocardiography (r = 0.711, p < 0.0001). The European guidelines for the diagnosis and treatment of pulmonary hypertension [1] have described the echocardiographic diagnosis of pulmonary hypertension “likely” when sPAP is >50 mmHg and pulmonary hypertension “possible” when sPAP is between 37 and 50 mmHg. When we adopted the above-mentioned classification in our PAH group, only 2 patients were classified to pulmonary hypertension “likely” and most of the patients to pulmonary hypertension “possible”, suggesting that echocardiography at rest should underestimate the PAH group. Meanwhile, echocardiography at post exercise is probably useful for accurate diagnosis in the PAH group when the cut-off value is set at approximately 70 mmHg. Data obtained from post-exercise echocardiography images provide additional findings for confirming pulmonary hypertension “possible”. Argiento et al. [20] have demonstrated that a high level of training and dedication allows for 88% of good-quality TR signals for the study of pulmonary hemodynamics during exercise.