Prognostic value of computed tomography derived fractional flow reserve for predicting cardiac events and mortality in kidney transplant candidates

Abstract

Background: Cardiac screening using coronary computed tomography angiography (CCTA) in kidney transplant candidates before transplantation yields both diagnostic and prognostic information. Whether CT-derived fractional flow reserve (FFR_CT) analysis provides prognostic information is unknown. This study aimed to assess the prognostic value of FFR_CT for predicting major adverse cardiac events (MACE) and all-cause mortality in kidney transplant candidates.

Methods: Among 553 consecutive kidney transplant candidates, 340 CCTA scans (61%) were evaluated with FFR_CT analysis. Patients were categorized into groups based on lowest distal FFR_CT; normal >0.80, intermediate 0.80-0.76, and low ≤0.75. In patients with ≥50% stenosis, a lesion-specific FFR_CT was defined as; normal >0.80 and abnormal ≤0.80. The primary endpoint was MACE (cardiac death, resuscitated cardiac arrest, myocardial infarction or revascularization). The secondary endpoint was all-cause mortality.

Results: Median follow-up was 3.3 years [2.0-5.1]. MACE occurred in 28 patients (8.2%), 29 patients (8.5%) died. When adjusting for risk factors and transplantation during follow-up, MACE occurred more frequently in patients with distal FFR_CT ≤0.75 compared to patients with distal FFR_CT >0.80: Hazard Ratio (HR): 3.8 (95%CI: 1.5-9.7), p ​< ​0.01. In the lesion-specific analysis with <50% stenosis as reference, patients with lesion-specific FFR_CT >0.80 had a HR for MACE of 1.5 (95%CI: 0.4-4.8), p ​= ​0.55 while patients with lesion-specific FFR_CT ≤0.80 had a HR of 6.0 (95%CI: 2.5-14.4), p ​< ​0.01. Abnormal FFR_CT values were not associated with increased mortality.

Conclusion: In kidney transplant candidates, abnormal FFR_CT values were associated with increased MACE but not mortality. Use of FFR_CT may improve cardiac evaluation prior to transplantation.

Keywords: Cardiac risk stratification; Chronic kidney disease; Computed tomography derived fractional flow reserve; Coronary artery disease; Coronary computed tomography angiography; Kidney transplantation; Major adverse cardiac event.