The prognostic and diagnostic implications of surveillance serial myocardial perfusion imaging in asymptomatic renal transplant candidates

Background: The utility of serial SPECT myocardial perfusion imaging (MPI) for CAD surveillance in asymptomatic ESRD patients awaiting kidney transplantation (KT) is uncertain.

Methods and results: We retrospectively investigated 700 asymptomatic KT candidates with ≥ 2 pre-transplant SPECT-MPIs (mean interval, 20 ± 13 months). Worsening MPI was defined as total perfusion deficit increase (ΔTPD) > 5%. High clinical risk was defined as ≥ 3 AHA/ACC KT risk factors. The primary outcome was major adverse cardiac events (MACE) of cardiac death or myocardial infarction. The initial MPI was normal in 462 (66%) subjects. On repeat MPI, ΔTPD > 5% was observed in 82 (12%) subjects, and the incidence increased with increasing time gap between MPIs (P = .006). During a mean follow-up of 16 ± 8 months, there were 119 (17%) MACEs. In the entire cohort, ΔTPD > 5% was not significantly associated with MACE (HR = 1.38; P = .210). ΔTPD > 5% was associated with increased MACE rate among patients with normal initial MPI (HR = 2.30; P = .005), but not among those with abnormal initial MPI (P = .260). There was a significant interaction between ΔTPD > 5% and initial MPI normalcy status in predicting MACE (interaction P = .018), such that the predictive value of ΔTPD is dependent on the initial MPI normalcy. Among subjects with normal initial MPI, ΔTPD > 5% was significantly associated with MACE only if the sum of KT risk factors was ≥ 3 (HR = 2.26; P = .016). Among 123 patients who underwent coronary angiography, ΔTPD > 5% was associated with a higher prevalence of obstructive CAD when the initial MPI was normal and the sum of KT risk factors was ≥ 3.

Conclusion: Among patients with ESRD waitlisted for KT, new/worsening MPI abnormalities are expected. On serial surveillance, ΔTPD > 5% is associated with MACE and obstructive CAD among those with a normal initial MPI and ≥ 3 AHA/ACC KT risk factors.