MATERIALS AND METHODS
Patient Data. This  prospective study included 73 adult patients referred clinically indicated left heart catheterization who also had transthoracic echocardiography (TTE) immediately before catheterization. ST-elevation and non-ST elevation myocardial infarction (MI), EF< %50, moderate to severe aortic and mitral regurgitation, and moderate to severe aortic and mitral stenosis were excluded. The medical histories, including all clinical and demographic data, were obtained from the electronic medical records. Laboratory results received within 24hrs before catheterization were obtained. The study protocol was reviewed and approved by the ethical committee.
Transthoracic Echocardiography. Two-dimensional echocardiographic imaging was performed in 73 patients who met the clinical criteria for study inclusion at Ankara University Cardiology Department Two-dimensional, color flow, continuous-pulse wave, and tissue Doppler TTE were performed by two experienced physicians using Vivid E9 imaging system (with an M5Sc-D transducer; GE Medical Systems, Chicago, USA) within 24hrs before left heart catheterization and measurements obtained in a standard manner as recommended by the American Society of Echocardiography. LV dimensions were measured in the parasternal long-axis view at end-systole and end-diastole. LV ejection fraction was calculated from 4 chamber view using the modified Simpson method.
TTE parameters assessed LV diastolic function.  Diastolic filling periods, including rapid filling, diastasis, and atrial contraction, were assessed by pulsed wave (PW) Doppler. Mitral inflow at the level of mitral valve leaflet tips was used to measure the peak early (E-wave) and late (A-wave) diastolic flow velocities and calculate the E/A ratio. Besides, tissue Doppler imaging (TDI) using PW was performed with the sample volume at the lateral and septal mitral annulus to obtain lateral e’ and medial e’ velocities. The arithmetic mean of lateral and medial e’ were defined as average e’, which was used to calculate the E/e’ ratio. Peak velocity of the tricuspid regurgitation (TR) jet was measured using continuous-wave Doppler. Left atrial volume was measured using a 4-chamber view and divided body surface area (BSA) to calculate the left atrial volume index (LAVi).
Speckle tracking 2D LV longitudinal strain . Speckle tracking 2D LV longitudinal average and the regional strain was measured using automated functional imaging (AFI). AFI was performed in 73 patients using an E9 imaging system (with a 4V-D transducer; GE Medical Systems, Chicago, USA) and transferred to Echo Pac imaging workstation (Echo Pac imaging system). LV longitudinal strain was performed according to standardized measurements recommended by the 2015 ASE Cardiac Chamber Quantification guideline.
LV catheterization.  Left heart catheterization was performed according to the standard procedure by an interventional cardiologist blinded to the echocardiographic data. Invasive LV systolic and diastolic pressure measurements were performed using a 6-Fr pigtail catheter (Boston Scientific, Marlborough, MA) placed in the left ventricle through the femoral or radial artery before the evaluation of coronary artery visualization. The measurements were obtained after the fluid-filled transducer was balanced with the zero level at the mid-axillary line. Continuous pressure tracings were acquired at least three consecutive respiratory cycles. LV pre-A pressure, which corresponds to the mean left atrial pressure(LAP) used as LV filling pressure recommended in the 2016 ASE/EACVI algorithm, and Pre-A pressure >12 mm Hg confirmed as elevated LV filling pressure.