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Evolution of Left Ventricular Size in Late Survivors of Surgery for Hypoplastic Left Heart Syndrome
Markus Bjurbom1, Ajay J Iyengar2, Florian Moenkemeyer3
1Department of Cardiac Surgery, Royal Children's Hospital, Melbourne, Victoria, Australia; Murdoch Children's Research Institute, Melbourne, Victoria, Australia.
Insights
Aortic and mitral atresia predict worse outcomes in hypoplastic left heart syndrome patients after Fontan palliation, regardless of left ventricular size. Severe left ventricular hypoplasia impacts long-term Fontan outcomes.
Area of Science:
- Pediatric Cardiology
- Congenital Heart Disease
- Cardiac Surgery
Background:
- Hypoplastic left heart syndrome (HLHS) poses significant risks, with aortic and mitral atresia being known early adverse event predictors.
- The long-term impact of these atresias and associated left ventricular (LV) morphology on outcomes after Fontan palliation remains unclear.
- Potential impairment of right ventricle (RV) function by a small, hypertrophied LV is a concern.
Purpose of the Study:
- To investigate the long-term effects of aortic and mitral atresia in HLHS patients undergoing Fontan procedure.
- To determine if a small, hypertrophied LV influences late adverse outcomes.
- To assess the relationship between initial LV/RV length ratio and subsequent ventricular growth and clinical outcomes.
Main Methods:
- Retrospective analysis of 30 HLHS patients surviving the Fontan procedure.
- Echocardiographic data collected at birth, pre-Fontan, and post-Fontan (mean follow-up 10.9 years).
- Key measurements included interventricular septum thickness, ventricular length, and calculation of the LV/RV length ratio at birth. Primary endpoint: death, transplantation, or Fontan takedown.
Main Results:
- A LV/RV length ratio cutoff of 0.55 differentiated patient groups.
- Group A (ratio ≤0.55) showed decreasing LV/RV ratio and septum thickness over time; Group B (ratio >0.55) remained static.
- Aortic and mitral atresia were potent predictors of adverse late outcomes (death, transplant, takedown), independent of initial LV length (HR 8.5, p=0.029).
Conclusions:
- Aortic and mitral atresia are associated with worse long-term outcomes post-Fontan in HLHS, irrespective of LV size or hypertrophy.
- Severely hypoplastic LVs exhibit limited proportional growth compared to RVs.
- These findings highlight the critical role of atresias in determining long-term prognosis in HLHS survivors.
Background:
Aortic atresia and mitral atresia are predictors of adverse events in early life in patients with hypoplastic left heart syndrome, but it is unclear whether late outcomes are also affected, and whether this impact is related to a small hypertrophied left ventricle (LV) that impairs right ventricle (RV) function.
Methods:
Thirty patients with hypoplastic left heart syndrome surviving with a Fontan procedure were identified. Follow-up echocardiograms were available at birth, before the Fontan procedure, and several years after. Mean follow-up time was 10.9 ± 3.1 years. Measurements included interventricular septum thickness and ventricular length. The LV/RV length ratio at birth was calculated, and its impact on later LV and septal growth was examined. The primary endpoint was a composite of death, transplantation, or Fontan takedown.
Results:
A cutoff LV/RV length ratio of 0.55 was identified: length ratio was 0.55 or less in group A (18 patients) and more than 0.55 in group B (12 patients) The LV/RV length ratio and interventricular septum thickness decreased over time in group A while remaining static in group B. The LV length at birth did not affect late adverse outcomes (hazard ratio 2.7, 95% confidence interval: 0.31 to 23.4, p = 0.37), whereas aortic atresia and mitral atresia were the most potent predictors of death or transplantation or takedown (hazard ratio 8.5, 95% confidence interval: 1.2 to 57.7, p = 0.029).
Conclusions:
Patients with aortic atresia and mitral atresia have worse outcomes even after Fontan independently of a small, thick, hypertrophied LV. The most severely hypoplastic LVs do not grow proportionally as much as the RVs.