Atrial Shunt Device Effects on Cardiac Structure and Function in Heart Failure With Preserved Ejection Fraction

Importance: Although the results of A Study to Evaluate the Corvia Medical Inc IASD System II to Reduce Elevated Left Atrial Pressure in Patients with Heart Failure (REDUCE LAP-HF II) trial were neutral overall, atrial shunt therapy demonstrated potential efficacy in responders (no latent pulmonary vascular disease and no cardiac rhythm management device). Post hoc analyses were conducted to evaluate the effect of shunt vs sham stratified by responder status. Objective: To evaluate the effect of atrial shunt vs sham control on cardiac structure/function in the overall study and stratified by responder status. Design, Setting, and Participants: This was a sham-controlled randomized clinical trial of an atrial shunt device in heart failure with preserved ejection fraction (HFpEF)/HF with mildly reduced EF (HFmrEF). Trial participants with evaluable echocardiography scans were recruited from 89 international medical centers. Data were analyzed from April 2023 to January 2024. Interventions: Atrial shunt device or sham control. Main Outcome Measures: Changes in echocardiographic measures from baseline to 1, 6, 12, and 24 months after index procedure. Results: The modified intention-to-treat analysis of the REDUCE LAP-HF II trial included 621 randomized patients (median [IQR] age, 72.0 [66.0-77.0] years; 382 female [61.5%]; shunt arm, 309 [49.8%]; sham control arm, 312 [50.2%]). Through 24 months, 212 of 217 patients (98%) in the shunt arm with evaluable echocardiograms had patent shunts. In the overall trial population, the shunt reduced left ventricular (LV) end-diastolic volume (mean difference, -5.65 mL; P <.001), left atrial (LA) minimal volume (mean difference, -2.8 mL; P =.01), and improved LV systolic tissue Doppler velocity (mean difference, 0.69 cm/s; P <.001) and LA emptying fraction (mean difference, 1.88 percentage units; P =.02) compared with sham. Shunt treatment also increased right ventricular (RV; mean difference, 9.58 mL; P <.001) and right atrial (RA; mean difference, 9.71 mL; P <.001) volumes but had no effect on RV systolic function, pulmonary artery pressure, or RA pressure compared with sham. In the shunt arm, responders had smaller increases in RV end-diastolic volume (mean difference, 5.71 mL vs 15.18 mL; interaction P =.01), RV end-systolic volume (mean difference, 1.58 mL vs 7.89 mL; interaction P =.002), and RV/LV ratio (mean difference, 0.07 vs 0.20; interaction P <.001) and larger increases in transmitral A wave velocity (mean difference, 5.08 cm/s vs -1.97 cm/s; interaction P =.02) compared with nonresponders randomized to the shunt, suggesting greater ability to accommodate shunted blood through the pulmonary circulation enabling LA unloading. Conclusions and Relevance: In this post hoc analysis of the REDUCE LAP-HF II trial, over 2 years of follow-up, atrial shunting led to reverse remodeling of left-sided chambers and increases in volume of right-sided chambers consistent with the shunt flow but no change in RV systolic function compared with sham. Changes in cardiac structure/function were more favorable in responders compared with nonresponders treated with the shunt, supporting the previously identified responder group hypothesis and mechanism, although further evaluation with longer follow-up is needed. Trial Registration: ClinicalTrials.gov Identifier: NCT03088033.