Intrapatient Variability in Tacrolimus Exposure Does Not Predict The Development of Cardiac Allograft Vasculopathy After Heart Transplant

OBJECTIVE: A high intrapatient variability in tacrolimus exposure is associated with poor long-term outcomes after kidney transplant. We hypothesized that a high intrapatient variability of tacrolimus exposure after heart transplant may be associated with cardiac allograft vasculopathy as a determinant of long-term survival of heart transplant recipients. MATERIALS AND METHODS: Eighty-six heart transplant recipients were included. Patients underwent coronary angiography at years 1 and 4 after transplant and were divided according to low and high intrapatient variability of tacrolimus exposure, with the median variability as cut-off. The primary outcome was the association between tacrolimus intrapatient variability and the progression of cardiac allograft vasculopathy score between years 1 and 4. Secondary outcome was this association with acute cellular rejection. RESULTS: There was no significant difference in the proportion of patients with high tacrolimus intrapatient variability in the group that progressed to higher grades of cardiac allograft vasculopathy (n = 15) versus the group without progression (n = 71) at 4-year follow-up (60.0% vs 47.9%; P = .57). There was no significant difference in the proportion of patients with high tacrolimus intrapatient variability between the 58 patients with 1 or more acute cellular rejection episodes and the 28 patients without rejection (51.7% vs 46.4%; P = .82). CONCLUSIONS: A high intrapatient variability in tacrolimus exposure does not appear to influence heart transplant outcomes, unlike its influence on kidney transplant function. A higher immunosuppression exposure after heart transplant, including the use of prednisone often in a combination of 3 immunosuppressive drugs, may protect against the effects of high intrapatient tacrolimus variability.