Interatrial Shunt Treatment for Heart Failure: The Randomized RELIEVE-HF Trial

BACKGROUND: An interatrial shunt may provide an autoregulatory mechanism to decrease left atrial pressure and improve heart failure (HF) symptoms and prognosis. METHODS: Patients with symptomatic HF with any left ventricular ejection fraction (LVEF) were randomized 1:1 to transcatheter shunt implantation versus a placebo procedure, stratified by reduced (≤40%) versus preserved (>40%) LVEF. The primary safety outcome was a composite of device-related or procedure-related major adverse cardiovascular or neurological events at 30 days compared with a prespecified performance goal of 11%. The primary effectiveness outcome was the hierarchical composite ranking of all-cause death, cardiac transplantation or left ventricular assist device implantation, HF hospitalization, outpatient worsening HF events, and change in quality of life from baseline measured by the Kansas City Cardiomyopathy Questionnaire overall summary score through maximum 2-year follow-up, assessed when the last enrolled patient reached 1-year follow-up, expressed as the win ratio. Prespecified hypothesis-generating analyses were performed in patients with reduced and preserved LVEF. RESULTS: Between October 24, 2018, and October 19, 2022, 508 patients were randomized at 94 sites in 11 countries to interatrial shunt treatment (n=250) or a placebo procedure (n=258). Median (25th and 75th percentiles) age was 73.0 years (66.0, 79.0), and 189 patients (37.2%) were women. Median LVEF was reduced (≤40%) in 206 patients (40.6%) and preserved (>40%) in 302 patients (59.4%). No primary safety events occurred after shunt implantation (upper 97.5% confidence limit, 1.5%; P<0.0001). There was no difference in the 2-year primary effectiveness outcome between the shunt and placebo procedure groups (win ratio, 0.86 [95% CI, 0.61-1.22]; P=0.20). However, patients with reduced LVEF had fewer adverse cardiovascular events with shunt treatment versus placebo (annualized rate 49.0% versus 88.6%; relative risk, 0.55 [95% CI, 0.42-0.73]; P<0.0001), whereas patients with preserved LVEF had more cardiovascular events with shunt treatment (annualized rate 60.2% versus 35.9%; relative risk, 1.68 [95% CI, 1.29-2.19]; P=0.0001; P_interaction<0.0001). There were no between-group differences in change in Kansas City Cardiomyopathy Questionnaire overall summary score during follow-up in all patients or in those with reduced or preserved LVEF. CONCLUSIONS: Transcatheter interatrial shunt implantation was safe but did not improve outcomes in patients with HF. However, the results from a prespecified exploratory analysis in stratified randomized groups suggest that shunt implantation is beneficial in patients with reduced LVEF and harmful in patients with preserved LVEF.