Atrial Reservoir Strain is Associated with Decreased Cardiac Index and Adverse Outcomes Post Fontan Operation

Fontan patients rely on atrial function for diastolic filling and to augment cardiac output. Emerging data suggests that diminished atrial function is predictive of poor outcomes in adults but studies evaluating the association between atrial mechanics in Fontan patients and outcomes are lacking. We sought to assess atrial function in Fontan patients using speckle tracking echocardiography to determine whether atrial function is associated with invasive hemodynamics and clinical outcomes. Single-center review of Fontan patients receiving both catheterization and echocardiogram from 2012-2017. Atrial reservoir, conduit and pump global longitudinal strain and strain rate were assessed by speckle tracking echocardiography. The primary outcome was a composite of all adverse clinical outcomes including cardiac hospitalizations, transplant and death. Eighty-three Fontan patients at a median age of 14.2 years (IQR 8.6, 21.7) at time of echocardiogram were included. Increased atrial reservoir strain (p = 0.04), atrial emptying fraction (p = 0.04) and atrial fractional area change (p = 0.04), were associated with higher cardiac index at baseline. There were no associations between atrial strain and systemic ventricular end diastolic pressure (EDP) at catheterization. Reservoir strain was inversely associated with the composite clinical outcome on multivariable Cox proportional hazard analysis (HR 0.96, p = 0.03). Reduced atrial function is associated with reduced cardiac index, but is not directly associated with ventricular EDP in Fontan patients. Reservoir strain is associated with an excess of adverse clinical outcomes in Fontan patients.