Abstract Body (Do not enter title and authors here): Background: Dyspnea on exertion is cardinal symptom in heart failure (HF) and may be caused by an unfavorable dynamic of ventricular interaction. This concept has been poorly addressed over time and we hypothesized that a careful study of the interventricular septum adaptations during maximal exercise in HF might be implicated in the limited cardiac reserve and uncoupling of right ventricular (RV) to pulmonary circulation (Pc), both yielding to a limited O2 uptake.

Aim: To study the pathophysiology behind biventricular interaction during exercise in HF, evaluating the role of septum displacement during exercise and how and whether it would affect peak exercise oxygen consumption (VO₂ peak) through a limited cardiac output (CO) increase and some degrees of RV to PC uncoupling assessed by TAPSE/PASP.

Methods: 22 HF performed a combined cardiopulmonary exercise testing imaging (CPET imaging) with RV 3D-imaging analysis and were compared with a control population.
3D imaging of the RV chamber was examined off-line using the 4D RV TomTec software and obtained 3D mesh of the RV model using custom software to obtain the mean curvature value of IVS in 4 regions of: inflow tract (RVIT), outflow tract (RVOT), apical and body. We acquired measurements of curvature during end-diastole (ED) and at end systole (ES) phases and obtained a parametric curvature map.

Results: HF patients (mean age 72±12, 27% female) typically showed an abnormal septal curve, with a more leftward configuration either at rest and under exercise (rest =−0.01±0.007 at ED, and −0.01±0.009 at ES; peak exercise= −0.01±0.006 at ED, and −0.01±0.007 at ES) compared to controls (rest=−0.02±0.002 at ED, and −0.02±0.006 at ES; peak exercise −0.02±0.0.006 at ED, and −0.02±0.01 at ES, Figure). Notably, the degree of the IVS curvature showed a linear correlation with an impaired gas exchange performance as indicated by a lower peak VO₂, a limited CO and impairment of TAPSE/PASP in HF (respectively, r=0.64, p<0.001, r=0.5, p<0.001, r=0.53, p<0.001 at ED during exercise; r=0.61, p<0.001 at ES during exercise; Figure).

Conclusions: In HF, the evidence of right to left IVS displacement appears worth of investigation, by intervening strictly to a reduced CO response, and RV-PA uncoupling during exercise. These findings clearly point to the utility of assessing how new and current therapeutic strategies may modulate the negative septum displacement and overall cardiac mechanics.