Role of strain imaging for risk stratification in Fontan patients with normal ventricular ejection fraction

Systemic ventricular (SV) strain imaging improves early detection of systolic dysfunction in patients with congenital heart disease and biventricular circulation. However, its role for risk stratification in the Fontan population has not been systematically studied. We hypothesized that among Fontan patients with normal SV ejection fraction (Echo_EF) at baseline, those with reduced SV longitudinal strain (Echo_LS) would have a higher risk of progressive SV systolic dysfunction, greater neurohormonal activation, and cardiovascular events (heart failure hospitalization/death/transplant) during follow-up.

We studied adults with Fontan palliation and normal SV systolic function (Echo_EF >50%) at baseline who underwent follow-up echocardiogram >36 months after the baseline echocardiogram. Echo_LS was assessed from the apical 4-chamber window using speckle tracking echocardiography. Patients were divided into reduced vs. normal Echo_LS groups, using -18% as the cut-off point. Echo_LS, Echo_EF, and NT-proBNP were assessed at baseline and follow-up encounters. Of 272 patients (age, 28 ± 8 years), 98 (36%) and 174 (64%) had reduced vs. normal Echo_LS. The reduced_Echo_LS group had progressive SV systolic dysfunction [worse temporal decline in Echo_EF (relative_Δ_Echo_EF -12.8% vs. -2.1%, P < 0.001)], and higher prevalence of new-onset SV systolic dysfunction [30% (29/98) vs. 8% (13/174), P < 0.001]. The reduced Echo_LS group also had greater neurohormonal activation [relative Δ_ NT-proBNP 36 (95%CI, 27-43) % vs. 17 (95%CI, 11-23) %, P < 0.001], and higher risk of cardiovascular events (adjusted hazard ratio 1.84, P = 0.009).

Echo_LS improves risk stratification in Fontan patients with normal Echo_EF and may provide an opportunity for early interventions to improve outcomes.