Biventricular Physiology of Iatrogenic Atrial Septal Defects Following Transcatheter Mitral Valve Edge-to-Edge Repair.

Objectives: The study sought to assess the acute hemodynamic effects of iatrogenic atrial septal defect (iASD) closure following transcatheter mitral valve edge-to-edge repair (TMVR).

Background: The potential hemodynamic and clinical consequences of an iASD following TMVR are currently subject to controversial debates.

Methods: In 21 patients with relevant left-to-right shunt flow (50% [IQR: 38% to 60%] of systemic perfusion volume) across an iASD following TMVR, interventional closure was performed with recordings of left ventricular (LV) and right ventricular (RV) pressure-volume loops during iASD occlusion.

Results: iASD occlusion led to a volume shift from the RV (RV end-diastolic volume index: pre 102 [IQR: 80 to 120] ml/m, post 92 [IQR: 70 to 111] ml/m; p < 0.001) to the LV (LV end-diastolic volume index: pre 91 [IQR: 74 to 124] ml/m, post 97 [IQR: 77 to 127] ml/m; p < 0.001) with reduced RV (3.49 [IQR: 2.07 to 3.58] l/min/m vs. 2.68 [IQR: 2.07 to 3.58] l/min/m; p < 0.001) but increased LV cardiac index (2.25 [IQR: 1.80 to 3.28] l/min/m vs. 2.77 [IQR: 1.90 to 3.34] l/min/m; p = 0.039). Although RV end-diastolic pressure decreased (pre 5.0 [IQR: 4.0 to 8.5] mm Hg, post 4.5 [IQR: 3.0 to 8.3] mm Hg; p = 0.024), LV end-diastolic pressure remained unchanged (pre 11.0 [IQR: 9.5 to 14.0] mm Hg, post 13.0 [IQR: 9.0 to 15.5] mm Hg; p = 0.142). LV transmural pressure increased (7.0 [IQR: 4.0 to 11.0] mm Hg vs. 11.0 [IQR: 7.0 to 15.0] mm Hg; p = 0.001) and LV eccentricity index decreased (p < 0.001). The change in LV transmural pressure correlated significantly with the change in LV-to-RV end-diastolic volume ratio (r = 0.674; p = 0.018). Right heart failure symptoms declined at 1-month follow-up (71% vs. 35%; p = 0.003) as did New York Heart Association functional class (≥III: 48% vs. 25%; p < 0.001).

Conclusions: iASD closure following TMVR leads to a volume shift from the RV to the LV with reduced pulmonary but increased systemic cardiac index and with favorable biventricular interaction at maintained LV filling pressure, resulting in a decline in heart failure symptoms at 1-month follow-up.