<prompt> Most common heart lesion in down syndrome:Endocardial cushion defectASD with ostium secundumVSDCoarctation of aorta  <response>: a. Endocardial cushion defectRef: Nelsons 20e p 610-614Most common cardiac defect in Down syndrome is Endocardial cushion defect or Atrioventricular septal defect 