Abdelhalim, Ahmed T

BACKGROUND: The purpose of this study was to assess the feasibility and prognostic value of cardiac output (CO) reserve assessment using exercise echocardiography in Fontan patients. We hypothesized that adults with Fontan palliation had lower CO reserve compared with controls, and impaired CO reserve was associated with greater congestion (NT-proBNP [N-terminal pro-B-type natriuretic peptide]) and cardiovascular events (death/transplant/heart failure hospitalization) in Fontan patients. METHODS: Thirty-seven Fontan patients and 61 controls underwent exercise echocardiography using a supine cycle ergometer. Doppler-derived CO and oxygen consumption (VO 2 ) were assessed at rest and every stage of exercise. CO reserve was calculated as ∆CO/Watt (∆CO/W) and ∆CO/∆VO 2 . RESULTS: Assessment of CO reserve was feasible in 95% of the Fontan group with modest reproducibility. Although both groups had similar CO at rest, the Fontan group had lower CO reserve with exercise as evidenced by lower ∆CO/W ratio (46±17 versus 57±19 mL/W; P <0.001) and lower ∆CO/∆VO 2 ratio (4.48±1.02 versus 5.37±2.18 mL/mL; P =0.03). There was a correlation between ∆CO/W ratio and log NT-proBNP (r=0.65; P <0.001), and between ∆CO/∆VO 2 ratio and log NT-proBNP (r=0.53; P =0.009). Impaired CO reserve was associated with congestion and cardiovascular events and provided improved prognostication (higher area under the curve and C statistics) above conventional echocardiographic indices and treadmill peak VO 2 . CONCLUSIONS: Patients with Fontan palliation had lower CO reserve, and impaired CO reserve was associated with congestion and cardiovascular events. Further studies are required to determine whether cardiac interventions can improve CO reserve and whether changes in CO reserve can be used as a surrogate end point for therapeutic response.

Abstract Aims 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. Methods and results We studied adults with Fontan palliation and normal SV systolic function (Echo_EF &gt;50%) at baseline who underwent follow-up echocardiogram &gt;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 &lt; 0.001)], and higher prevalence of new-onset SV systolic dysfunction [30% (29/98) vs. 8% (13/174), P &lt; 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 &lt; 0.001], and higher risk of cardiovascular events (adjusted hazard ratio 1.84, P = 0.009). Conclusion Echo_LS improves risk stratification in Fontan patients with normal Echo_EF and may provide an opportunity for early interventions to improve outcomes.

Background Atrial dysfunction is a risk factor for atrial arrhythmia and can be detected by atrial strain imaging in patients with biventricular circulation. However, the role of atrial strain imaging for risk stratification of atrial arrhythmia in patients with Fontan palliation has not been studied, despite the high prevalence and prognostic implications of atrial arrhythmia in this population. We hypothesized that pulmonary venous atrial strain was associated with new‐onset and recurrent atrial arrhythmia in Fontan physiology. Method and Results This is a retrospective study of adults with Fontan palliation and no prior history of atrial arrhythmia who underwent atrial strain imaging by speckle tracking echocardiography (2003–2023). New‐onset and recurrent atrial arrhythmias were ascertained from baseline encounter to last follow‐up. Of 404 patients, atrial reservoir strain assessment was feasible in 329 patients (81%), with modest intra‐ and interobserver agreement. The median atrial reservoir strain was 18% (interquartile range, 13%–24%), and atrial dysfunction (atrial reservoir strain <28%) was present in 294 (89%). Atrial reservoir strain <15% was associated with new‐onset atrial arrhythmia (adjusted hazard ratio [HR], 1.59 [95% CI, 1.09–2.34]; P =0.009), and recurrent atrial arrhythmia (adjusted HR, 2.01 [95% CI, 1.06–3.93]; P =0.003). Rhythm control therapy was associated with lower risk of recurrence compared with rate control therapy (adjusted HR, 0.92 [95% CI, 0.86–0.98]; P =0.003). Conclusions Atrial dysfunction was common and was associated with new‐onset and recurrent atrial arrhythmias. The higher prevalence of atrial arrhythmias in patients with reduced atrial strain and the apparent protective effect of rhythm control therapy suggest that rhythm control therapy may be the preferred treatment in patients with reduced atrial strain.

BACKGROUND: Bioprosthetic valve dysfunction and reoperations/reinterventions are common after aortic valve replacement (AVR) with bioprosthetic valves, leading to cycles of left ventricular (LV) pressure overload and unloading. The purpose of this study was to compare postoperative changes in LV structure and function and their relationship to clinical outcomes in young patients who underwent AVR with bioprosthetic valves (Bio_AVR group) versus mechanical prosthetic valves (Mech_AVR group). METHODS: Retrospective study of adults with congenital heart disease who underwent AVR at Mayo Clinic (2003–2023). The Bio_AVR group was matched 1:2 to the Mech_AVR group. LV indices (LV mass index, relative wall thickness, LV global longitudinal strain, averaged e′, and averaged E/e′) and clinical indices (NT-proBNP [N-terminal pro-B-type natriuretic peptide] and New York Heart Association class) were assessed preoperatively, and at 1, 5, and 10 years post-AVR. RESULTS: We studied 151 and 302 patients in the Bio_AVR and Mech_AVR groups, respectively (age 38±16 years, 58% males). Both groups had similar LV and clinical indices at baseline and 1 year post-AVR. However, the Bio_AVR group had higher LV mass index, relative wall thickness, and averaged E/e′, and lower averaged e′ and LV global longitudinal strain at 5 and 10 years post-AVR. Of 51 patients from the Bio_AVR group who underwent a second AVR, there was less robust improvement in LV indices and clinical indices after the second AVR compared with the first AVR. CONCLUSIONS: AVR with a bioprosthetic valve was associated with progressive LV hypertrophy and dysfunction, and worsening clinical status compared with mechanical prosthetic valves. This provides further evidence against the use of bioprosthetic AVR in young patients.