Relationship between Right Ventricular Longitudinal Strain, Invasive Hemodynamics, and Functional Assessment in Pulmonary Arterial Hypertension

Abstract

Background and objectives: Right ventricular longitudinal strain (RVLS) is a new parameter of RV function. We evaluated the relationship of RVLS by speckle-tracking echocardiography with functional and invasive parameters in pulmonary arterial hypertension (PAH) patients.

Subjects and methods: Thirty four patients with World Health Organization group 1 PAH (29 females, mean age 45±13 years old). RVLS were analyzed with velocity vector imaging.

Results: Patients with advanced symptoms {New York Heart Association (NYHA) functional class III/IV} had impaired RVLS in global RV (RVLSglobal, -17±5 vs. -12±3%, p<0.01) and RV free wall (RVLSFW, -19±5 vs. -14±4%, p<0.01 to NYHA class I/II). Baseline RVLSglobal and RVLSFW showed significant correlation with 6-minute walking distance (r=-0.54 and r=-0.57, p<0.01 respectively) and logarithmic transformation of brain natriuretic peptide concentration (r=0.65 and r=0.65, p<0.01, respectively). These revealed significant correlations with cardiac index (r=-0.50 and r=-0.47, p<0.01, respectively) and pulmonary vascular resistance (PVR, r=0.45 and r=0.45, p=0.01, respectively). During a median follow-up of 33 months, 25 patients (74%) had follow-up examinations. Mean pulmonary arterial pressure (mPAP, 54±13 to 46±16 mmHg, p=0.03) and PVR (11±5 to 6±2 wood units, p<0.01) were significantly decreased with pulmonary vasodilator treatment. RVLSglobal (-12±5 to -16±5%, p<0.01) and RVLSFW (-14±5 to -18±5%, p<0.01) were significantly improved. The decrease of mPAP was significantly correlated with improvement of RVLSglobal (r=0.45, p<0.01) and RVLSFW (r=0.43, p<0.01). The PVR change demonstrated significant correlation with improvement of RVLSglobal (r=0.40, p<0.01).

Conclusion: RVLS correlates with functional and invasive hemodynamic parameters in PAH patients. Decrease of mPAP and PVR as a result of treatment was associated with improvement of RVLS.

Keywords: Familial primary pulmonary hypertension; Heart ventricles; Ventricular function, right.

Fig. 1. Association of right ventricular longitudinal strain (RVLS) with clinical symptoms. Patients with advanced symptoms (NYHA Fc III/IV) have significantly impaired global right ventricular longitudinal strain (RVLS_global) value. Error bar equals 1SD. RV: right ventricle, NYHA Fc: New York Heart Association functional class.

Fig. 2. Correlations between A) right ventricular global longitudinal strain of right ventricle and 6-minute walking distance; B) right ventricular global longitudinal strain of right ventricle and logarithmic transformation of B-type natriuretic peptide. C) global longitudinal strain of right ventricular free wall and 6-minute walking distance; D) global longitudinal strain of right ventricular free wall and logarithmic transformation of B-type natriuretic peptide. RVLS_global: Right ventricular global longitudinal strain of right ventricle, RVLS_FW: global longitudinal strain of right ventricular free wall, Log_BNP: B-type natriuretic polypeptide concentration expressed as a logarithm of its value, RV: right ventricle.

Fig. 3. Correlations between A) right ventricular global longitudinal strain and mean pulmonary arterial pressure; B) global longitudinal strain of right ventricular free wall and mean pulmonary arterial pressure; C) right ventricular global longitudinal strain and cardiac index; D) global longitudinal strain of right ventricular free wall and cardiac index; E) right ventricular global longitudinal strain and pulmonary vascular resistance; F) global longitudinal strain of right ventricular free wall and pulmonary vascular resistance. mPAP: mean pulmonary arterial pressure, RVLS_global: right ventricular global longitudinal strain of right ventricle, RVLS_FW: global longitudinal strain of right ventricular free wall, PVR: pulmonary vascular resistance.

Fig. 4. Correlations between the changes of hemodynamic parameters and right ventricular global longitudinal strain with specific pulmonary vasodilator therapy. Change of variables was derived by subtraction of follow-up value from baseline value, and positive values indicate better response. A) change in right ventricular global longitudinal strain of right ventricle versus change in mean pulmonary arterial pressure; B) change in global longitudinal strain of right ventricular free wall versus change in mean pulmonary arterial pressure; C) change in right ventricular global longitudinal strain of right ventricle versus change in pulmonary vascular resistance; D) change in global longitudinal strain of right ventricular free wall versus change in pulmonary vascular resistance. mPAP: mean pulmonary arterial pressure, RVLS_global: right ventricular global longitudinal strain of right ventricle, PVR: pulmonary vascular resistance, WU: wood units, RVLS_FW: global longitudinal strain of right ventricular free wall.

Fig. 5. RVLS_global during follow up. Data are presented at baseline, within the first 6 months, and after more than a year after initial echocardiogram. Patients were separated into the group already on treatment for pulmonary hypertension (n=6), and a group of in whom treatment was initiated or in intensified (n=28) after the baseline echocardiogram. Patients who were already on treatment had better RVLS_global (p=0.04) during the study period. However, patients in whom treatment was initiated or intensified showed significant improvement in RVLS_global during follow up (p=0.03). Error bars show 1 standard deviation. RVLS_global: right ventricular global longitudinal strain of right ventricle.