Right Ventricular Ejection Fraction, Measured During Routine Inter-stage Cardiac Magnetic Resonance Imaging, Predicts Outcome for Patients with Hypoplastic Left Heart Syndrome

  • Dr Marina Hughes, Great Ormond Street Hospital for Children, London, UK, United Kingdom
  • Dr Vivek Muthurangu, Great Ormond Street Hospital for Children, London, UK, United Kingdom
  • Dr Andrew Taylor, Great Ormond Street Hospital for Children, London, United Kingdom
  • Mr Victor Tsang, Great Ormond Street Hospital for Children, London, UK, United Kingdom
  • Dr Katherine Brown, Great Ormond Street Hospital for Children, London, UK, United Kingdom

    • Background
    A protocol involving cardiac MRI for inter-stage assessment of all infants with hypoplastic left heart syndrome (HLHS)has been adopted by our unit since 2003.
    Methods
    All locally followed survivors of the Norwood I procedure were included, following imaging under GA on a 1.5T scanner. Coarctation (CoA) size was indexed against diaphragmatic descending aorta. The primary outcome measure was survival to analysis date (October 08). Secondary, functional outcome measures were RV ejection fraction (RVEF), and cardiac output.
    Results
    The cohort comprised 30 patients; of which 15 were Sano-type, with median age and weight at scan 91 (33 – 291) days, and 5 (3.2 – 11) kg.
    The median CoA area index for all patients was 0.52 (0.22 – 1.0). Twenty-one (70%) had a CoA area index < 0.7. There was significant correlation between CoA index and cardiac output (p = 0.04), but CoA indices were not correlated with RVEF.
    The median RVEF for this cohort was 53% (30 – 81%). There were 7 deaths, during total follow-up time 67 person-years.
    The RVEF was strongly predictive of death, with hazard ratio 0.92 (p = 0.02). Other factors, such as the CoA and PA indices, anatomical type, age at MRI and cardiac output, did not predict death.
    Conclusions
    Cardiac MRI provides comprehensive 3D imaging and gives functional indices that predict outcome. Death is more likely in HLHS patients with lower RV ejection fraction at inter-stage MRI. Measures to preserve RV systolic function are paramount in the complex management of these patients.