Background: Interatrial shunt device (IASD) effects have been described in patients with heart failure and ejection fractions (EFs) >/=40%. However, baseline characteristics that correlate with greatest hemodynamic effects are unknown. On the basis of fundamental principles, we hypothesized that larger pressure gradients between left and right atria would yield greater shunt flow and greater hemodynamic effects.
Methods and Results: REDUCE LAP-HF (Reduce Elevated Left Atrial Pressure in Patients With Heart Failure) was a multicenter study that investigated IASD safety and performance. Sixty-four patients with EF >/=40% underwent device implantation followed by hemodynamic assessments at rest and exercise, including pulmonary capillary wedge pressure (PCWP, surrogate for left atrial pressure) and central venous pressure (CVP). At 6 months, IASD resulted in an average pulmonary-to-systemic blood flow ratio of 1.27 and increased exercise tolerance. The PCWP-CVP gradient (ie, the driving pressure for shunt flow) decreased at peak exercise from 16.8+/-6.9 to 11.4+/-5.5 mm Hg, because of increased CVP (17.5+/-5.4 to 20.3+/-7.9 mm Hg; P=0.04) and decreased PCWP (34.1+/-7.6 to 31.6+/-8.0 mm Hg; P=0.025). Baseline PCWP-CVP gradient during exercise correlated with changes of both PCWP-CVP and PCWP: Delta(PCWP-CVP)=10.0-0.89.(PCWP-CVP)baseline ( r(2)=0.56) and DeltaPCWP=7.54-0.60.(PCWP-CVP)baseline ( P=0.001). Hemodynamics of patients with EF >/=50% and those with EF <50% responded similarly to IASD.
Conclusions: In heart failure patients with EF >/=40%, IASD significantly reduced PCWP and PCWP-CVP at peak exercise. Patients with higher baseline PCWP-CVP gradient had greater reductions in both parameters at follow-up. Results were sustained through 12 months and were independent of whether EF was >/=50% or between 40% and 49%. Additional studies will help further define the baseline hemodynamic predictors of exercise, hemodynamic, and clinical efficacy of the IASD. Clinical Trial Registration URL: https://www.clinicaltrials.gov . Unique identifier: NCT01913613.