Ambulatory Fontan pressure monitoring: Results from the implantable hemodynamic monitor Fontan feasibility cohort (IHM-FFC).

Background: Implantable invasive hemodynamic monitoring (IHM) using the CardioMEMS™ HF system has been shown to reduce heart failure (HF) hospitalizations. IHMs have not yet been used in congenital heart disease (CHD). We aimed to evaluate feasibility and mid-term outcomes of IHM use in the single ventricle/Fontan population.

Methods: Six adult Fontan patients (>1 HF admission, NYHA FC >3) were enrolled (30 ± 7 years old, mean pulmonary artery pressure (mPA) 16 ± 4.7 mm Hg). Heart failure mediated events (HFME) were evaluated for 12 months: CV medication change, hospital admission, paracentesis, and change in orthotopic heart transplant (OHT) listing status.

Results: The IHM device was successfully placed in all participants. In total there were 671 IHM transmissions and 25(3.7%) HFME. The mean PA pressure across all episodes was 18.2 ± 6.6 mm Hg (range 6-40 mm Hg). Higher mPA pressures were associated with greater odds of having a HFME (OR 1.17 [1.09, 1.25], p < 0.0001). Mean PA pressure had good ability to discriminate transmissions associated with HFME (AUC 0.76 [0.654, 0.866]), with mean PA pressures >24 mm Hg or individual mPA change >4 mm Hg, best discriminating transmissions associated with HFME.

Conclusions: In the first feasibility series of adult Fontan patients undergoing CardioMEMS™ implantation we demonstrate early technical success and no device-related adverse events. We propose that ambulatory mean PA pressures >24 mm Hg or individual mPA change >4 mm Hg may be associated with more HFME. Further large-scale studies in this population are recommended.