Adult Congenital Heart Disease

The “Super-Fontan” Phenotype: Characterizing Factors Associated with High Physical Performance

The "Super-Fontan" Phenotype: Characterizing Factors Associated with High Physical Performance. Tran DL, Celermajer DS, Ayer J, Grigg L, Clendenning C, Hornung T, Justo R, Davis GM, d'Udekem Y, Cordina R. Front Cardiovasc Med. 2021 Dec 7;8:764273. doi: 10.3389/fcvm.2021.764273. eCollection 2021. PMID: 34950712    Take Home Points: Fontan patients who were very active at a young age, have a normal BMI, had earlier Fontan completion and had left systemic ventricle are more likely to be associated with better exercise capacity or “Super-Fontan”. Super-Fontans are associated with better lung function and exercise self-efficacy. Super-Fontans were not affected by the type of Fontan circuits, the duration of Fontan and the presence of fenestration in the Fontan circuit.  When the patients reach adulthood, no difference in the physical activity levels and the perceived quality of life were observed despite the difference in the exercise capacity.  Commentary from Dr. MC Leong (Kuala Lumpur), section editor of ACHD Journal Watch: Fontan palliation may have improved the life expectancy and quality of life in patients with single ventricular physiology, but generally, patients do suffer from impaired exercise capacity. While exercise capacity differs from one patient to another, some Fontan patients do have exercise capacity comparable to people with normal biventricular hearts or even better. They are the so-called “Super-Fontans”. Higher exercise capacity in patients is associated with a better prognosis. In this study, the authors aimed to characterize factors associated with these “Super-Fontan” phenotypes.   Patients in the Australian and New Zealand Fontan Registry with cardiopulmonary exercise tests (CPET) were identified. Patients were considered “Super-Fontan” if they achieve a normal exercise and work capacity (>80% predicted). Conversely, if they achieve an exercise or work capacity < 80%, they were assigned to the control group. The ratio between Super-Fontan and control in the study was 1:3 (n=15 vs n=45). All these patients underwent the following tests for comparison: (a) exercise self-efficacy (assessment of an individual belief in their ability to continue exercising) and health-related quality of life; (b) CPET and spirometry; (c) physical activity across the lifespan (a recall of sports and physical activities participated during childhood (4-12 years old), high school and early adulthood (12-21 years old) and older adulthood (>22 years old); and (d) current level of physical activity.   Compared to the control group, the Super-Fontans were associated with a lower age of Fontan procedure, morphologically left dominant ventricle and not being obese, which underscores the importance of early volume unloading with early Fontan completion, and the concerns of increased mechanical loading and risk of obstructive sleep apnea with obesity. No significant differences between groups were noted in terms of patient’s age, type of Fontan circuit, duration after Fontan completion and the presence of Fontan fenestration (Table 1). As for the CPET and lung function, peak respiratory exchange ratio, minute ventilation and heart rate reservice were significantly higher in Super-Fontans (Table 2). In addition, the Super-Fontan tended to have normal lung function compared to controls (Table 3). Super-Fontans were noted to have higher hours per week of sports in most of their lifespan (Figure 1). However, the higher exercise capacity did not translate to a statistical significance in health-related quality of life during adulthood. In terms of the current physical activity levels, no statistical difference was noted between the Super-Fontan and control (Figure 2) which showed a slowing down of physical activity as one ages or starts his/her working life and that the benefit of higher exercise capacity is not as obvious as it were during childhood and young adulthood.   Although small in sample size and retrospective in nature, the group should be commended for their attempt in profiling the phenotypical features of a good Fontan. It encourages healthcare workers to promote a healthy lifestyle in patients with Fontan circuit eg. living an active lifestyle, maintaining ideal body weight, avoidance of cigarette smoking and the prevention of respiratory infections which may affect the lung functions of patients. Such a study is also useful in guiding risk stratification of patients and resource allocation.             


Right Heart Dysfunction in Adults with Coarctation of Aorta: Prevalence and Prognostic Implications

Right Heart Dysfunction in Adults with Coarctation of Aorta: Prevalence and Prognostic Implications. Egbe AC, Miranda WR, Jain CC, Connolly HM. Circ Cardiovasc Imaging. 2021 Dec;14(12):1100-1108. doi: 10.1161/CIRCIMAGING.121.013075. Epub 2021 Dec 8. PMID: 34875855   Take Home Points: Right heart anatomic and hemodynamic abnormalities were evaluated by echocardiography in 821 patients with native (176) or repaired (645) coarctation who presented for evaluation between January 2000 and December 31, 2018. Median follow up was 8.2 years. Right heart anatomic and hemodynamic abnormalities were present in almost 20% of the population; all patients studied had coarctation gradients < 20 mmHg but over 50% had hypertension. Cardiovascular events (hospitalization for heart failure = 9%; transplant = 1%; cardiovascular death = 10%) occurred in 54 (14%) patients. Using multivariate analysis, the authors determined that abnormalities in 4 indices - RA strain, RA volume index, RV global longitudinal strain and RV systolic pressure - were highly associated with cardiovascular events. The authors used these indices to generate a Right Heart Hemodynamic Score (RHHS), or risk scores, to help prognosticate in these patients. Commentary from Dr. Thomas Zellers (Dallas, USA), section editor of Congenital Heart Disease Interventions and ACHD Journal Watch: Patients with left heart obstruction develop LV systolic and diastolic dysfunction which can lead to pulmonary remodeling, pulmonary hypertension and RV dysfunction. Echo is capable of evaluating right heart anatomic and hemodynamic dysfunction and these indices are used for prognostication in patients with left heart disease. Coarctation of the aorta is known to lead to left heart disease and early coronary disease but there is limited data on its effect on right heart indices and their prognostic significance in this population.   These authors studied 821 patients who presented between January 2000 and December 2018 with the diagnosis of coarctation, as an isolated disease (n=563) or in combination with LV outflow (n= 204; aortic stenosis, subaortic stenosis, supra-aortic stenosis with mean gradient > 20 mmHg or > 2+ AI) or LV inflow (n=54; mitral stenosis > 3 mmHg or regurgitation > moderate) disease. Mean age was 32 (21-46) with 58% males. Half of the patients had hypertension; beta blockers were prescribed 29% of the time, calcium channel blockers 13% of the time and RAAS antagonists and diuretics were prescribed 28% and 11% respectively. They further validated their studies by dividing the group into 2 random cohorts, the derivation and validation cohorts (n= 411 and 410) and compared the right heart indices and cardiovascular outcomes. Median follow up was 8.2 years in the derivation cohort.   The authors used echocardiography with speckle tracking strain imaging to evaluate the right heart including RA volume index, RA reservoir strain, RA pressure estimates, RV end diastolic area, RV global longitudinal strain, tricuspid regurgitation and estimates of RV and PA systolic pressures. These seven indices were used to generate a right heart hemodynamic score (RHHS) based on univariate and multivariate analysis.   The primary outcome was a composite of cardiovascular events, including hospitalization for heart failure, transplant or cardiovascular death.   Right heart indices were abnormal in approximately 20% of the patients as follows: RA dysfunction 16%, RA volume enlargement 28%, RA hypertension 17%, RV systolic dysfunction 14%, RV enlargement 9%, at least moderate tricuspid regurgitation in 5% and pulmonary hypertension in 20%. All indices were worse in patients with LV inflow and LV outflow disease compared to isolated coarctation. There was also a statistical correlation between RV systolic pressure/pulmonary hypertension and the findings of RV longitudinal strain and RA reservoir strain.   The derivation and validation cohorts were used to compare RHHS and subsequent model fit. In the derivation cohort of 411 patients, 9% were hospitalized for heart failure, 1% required transplant and 10% died from cardiovascular disease or its associated complications for a total of 54 patient (14%) with cardiovascular events. All seven right heart indices were associated with endpoint cardiovascular events on univariate analysis; four indices (RA strain, RA volume index, RV longitudinal strain and RV systolic pressure) remained independently associated with cardiovascular events on multivariate analysis and the RHHS was generated (0-5) using these 4 variables. RA reservoir strain, RA volume index and RV global longitudinal strain were each assigned 1 point, and RVSP > 40 mmHg was assigned 2 points. The patients were stratified based on their RHHS into low risk (RHHS 0-1), moderate risk (RHHS 2-3) and high risk (RHHS 4-5). Moderate and high risk scores were more likely to be associated with inflow and outflow disease and older age, but not with age at repair. Residual coarctation mean gradient did not correlate with right heart indices. In addition to the right heart indices, LV global longitudinal strain, atrial fibrillation and hypertension (even with low coarctation gradients) were independently associated with cardiovascular events. When the two cohorts, the derivation and validation cohorts, were compared, the findings were similar between the two groups and the C-statistics for the models suggested a tight fit (C-statistics of 0.72 and 0.71, respectively).   Overall, right heart indices were abnormal in almost 20% of patients in the study group. Abnormal right heart indices and RHHS were associated with cardiovascular events and can be used for prognostication in this group. Interestingly, residual coarctation or time from repair at the time of evaluations had no prognostic significance suggesting that the abnormalities seen in the left heart leading to right heart abnormalities may be longer standing. Looking earlier for these abnormalities and/or earlier proactive/preventive therapy studies are the next steps to evaluating cause and prevention.   Limitations: retrospective study, no invasive hemodynamic indices and no evaluation of medical interventions to alter outcomes.