Septal Curvature Is Marker of Hemodynamic, Anatomical, and Electromechanical Ventricular Interdependence in Patients with Pulmonary Arterial Hypertension

Aims: The objective of this study was to determine the factors independently associated with septal curvature in patients with pulmonary arterial hypertension (PAH). Methods: Eighty-five consecutive patients with PAH who had an echocardiogram and a right heart catheterization within 24 hours of each others were included in the study. Septal curvature was assessed at the mid-papillary level using the eccentricity index (EI). Marked early systolic septal anterior motion was defined as a change in EI > 0.2 between end-diastole and early systole. Inter-ventricular mechanical delay was calculated as the percent time difference between right ventricular (RV) to left ventricular (LV) end-ejection time normalized for the RR interval. Results: Average age was 45 +/- 11 years and the majority of patients were women (75%). Mean right atrial pressure was 11 +/- 7 mmHg, mean PAP was 52 +/- 13 mmHg, relative RV area 1.8 +/- 0.9, and RV fractional area change 24 +/- 8%. End-diastolic EI was 1.6 +/- 0.4 and systolic EI was 2.5 +/- 0.8. On multivariate analysis relative pulmonary pressure, relative RV area, and inter-ventricular mechanical delay were independently associated with systolic EI (R-2 = 0.72, P < 0.001). Independent determinants of diastolic EI included relative RV area and mean PAP (R-2 = 0.69, P < 0.001). A systolic EI > 1.08 differentiated patients with PAH from healthy controls with an AUC = 0.99. Patients with early systolic septal anterior motion (44% of subjects) had lower exercise capacity, more extensive ventricular remodeling, and worst ventricular function. Conclusion: Septal curvature is a useful marker of structural, hemodynamic, and electromechanical ventricular interdependence in PAH.