Purpose: Non-invasive immune monitoring of heart transplant (HTx) patients (pts) is increasing in use. The AlloMap® blood test has proven helpful in surveillance of cardiac allograft rejection, while the Cylex™ blood test is useful to assess global immune function. A higher Cylex is indicative of lower immunosuppression and thus higher risk of rejection. While Allomap® has high negative predictive value for rejection, its positive predictive value is low. We chose to assess whether concomitant Cylex™ score may improve the predictive ability of Allomap® for rejection.

Methods: Between 2010-2014, we identified 209 instances of concomitant Cylex™ and Allomap® scores in 104 post-HTx pts. Occurrences were divided into two groups: those with low Cylex™ scores (<225) and those with moderate to high scores (≥225). We assessed the proportion of concomitant Allomaps® that were elevated (defined as ≥30 before 6-months post-HTx, and ≥34 greater than 6-months post-HTx) in each group. For instances where a concomitant elevated Allomap® existed, concomitant endomyocardial biopsies were assessed and rate of rejection was compared between groups.

Results: There was no significant difference in the proportion of elevated Allomaps between low and moderate-to-high Cylex™ groups. When comparing instances of each elevated Allomap® per group, concomitant biopsies revealed no significant difference between the two groups in occurrence of biopsy-proven ISHLT 1R, 2R, or 3R rejection. (See table)

Conclusion: Concomitant Cylex™ score does not appear to be helpful in improving predictive ability of the Allomap® test for rejection post-HTx. Further studies are warranted.

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