Introduction: Current guidelines recommend physiological evaluation of borderline coronary artery stenoses using hyperemic (fractional flow reserve [FFR]) and nonhyperemic (instantaneous wave‑free ratio [iFR] and resting full‑cycle ratio [RFR]) methods. However, comorbidities, such as diabetes mellitus (DM), may influence the results of the assessment.
Objectives: We sought to investigate the impact of DM and insulin treatment on the discordance between FFR and iFR/RFR.
Patients and methods: A total of 417 intermediate stenoses in 381 patients underwent FFR and iFR/RFR assessment. FFR lower than or equal to 0.8 and iFR/RFR lower than or equal to 0.89 indicated significant ischemia. The patients were categorized based on DM diagnosis and insulin treatment status.
Results: Of the 381 patients, 154 (40.4%) had DM. Among these, 58 patients (37.7%) received insulin treatment. Diabetic patients had higher body mass index and glycated hemoglobin levels, and lower ejection fraction. FFR and iFR/RFR analyses were conducted in 417 vessels with available measurements for both tests. A good correlation between FFR and iFR/RFR was confirmed in both diabetic (R = 0.77) and nondiabetic (R = 0.74) patients. Discordance between FFR and iFR/RFR occurred in approximately 20% of cases, and the frequency of discordance was not affected by the diabetic status. However, insulin‑treated DM was independently associated with a higher risk of negative FFR and positive iFR/RFR discordance (odds ratio, 4.61; 95% CI, 1.38-15.4; P = 0.01). Also, the optimal cutoff value for FFR identifying significant ischemia in DM patients treated with insulin was higher (0.84) than the generally recommended value.
Conclusions: The rate of FFR and iFR/FFR discordance was similar regardless of the diabetes status, and insulin‑treated DM was associated with an increased risk of negative FFR and positive iFR/RFR discordance.