Early (1-Year) Class II Donor Specific Antibodies without Complement-Binding Appears Benign after Heart Transplantation

Purpose The development of donor specific antibody (DSA) has been reported to have poor outcome after heart transplantation (HTx). DSA particularly class II, may result in graft dysfunction, increased mortality, development of cardiac allograft vasculopathy (CAV) and non-fatal major adverse cardiac events (NF-MACE). These class II DSA appear to form later after heart transplant. It is not firmly established whether early class II DSA (within the first year after transplant) has adverse clinical effects. Methods Between 2010-15, we assessed 35 HTx patients (pts) who developed de novo class II DSA in the 1 year after HTx. Each pt had subsequent follow up of 5 years for mortality, development of CAV, as defined by stenosis ≥30% by angiography), and development of NF-MACE: myocardial infarction, new congestive heart failure, percutaneous coronary intervention, defibrillator/pacemaker implant, stroke). In subgroup analysis, class II DSA was divided into those DSA that were complement-binding (C1q+) compared to those without complement-binding. All DSA pts were compared to pts without DSA (n=413). Results At 5 years after HTx, there appeared to be no difference between groups in 5-year survival, 5-year freedom from CAV and NF-MACE. Those DSA that were C1q+ had significantly lower 5-year survival and freedom from NF-MACE compared to DSA pts without C1q+ and to the control group. (see table) Conclusion Early de novo class II DSA that are not complement-binding do not appear to result in increased mortality or development of CAV or NF-MACE. However, early class II DSA that are complement-binding, appear to impact outcome.