Study population cohorts
We designed a cross-sectional study in which we recruited consecutive patients who were evaluated in the Nuclear Cardiology Department (NCD) at the National Institute of Cardiology Ignacio Chavez, between the period of June 2018 to December 2019. The patients attended our institution’s outpatient clinic due to dyspnea on exertion, fatigue, and dizziness and were sent for a transthoracic echocardiogram for further evaluation. All patients underwent conventional two-dimensional and Doppler transthoracic echocardiography, along with velocity vector imaging to assess the right heart chamber strain parameters. We excluded subjects with congenital heart diseases, prior myocardial infarction, sarcoidosis, mild or severe valvular disease, or subjects classified with unspecified cardiomyopathies. Patients with low echocardiographic image quality were excluded in the final analysis. We defined a control group which comprised of subjects who had normal pulmonary artery pressure values by echocardiographic measurement of peak tricuspid regurgitation velocity within our cohort sample. To assess inter-rater reliability and reproducibility of echocardiographic sPAP parameters, thirteen selected subjects from our first cohort were assessed at heart catheterization performed 10 days after the echocardiographic study. Written informed consent was obtained from all participants.