Impact of TCFA on Unanticipated Ischemic Events in Medically Treated Diabetes Mellitus: Insights From the PROSPECT Study

Objectives This study sought to investigate the relationship between thin-cap fibroatheromas (TCFAs) on major adverse cardiac events (MACEs) arising from medically treated nonculprit lesions (NCLs) in patients with acute coronary syndromes (ACS) with and without diabetes mellitus (DM). Background MACEs occur frequently in patients with DM and ACS. The impact of plaque composition on subsequent MACEs in DM patients with ACS is unknown. Methods In the PROSPECT (Providing Regional Observations Study Predictors of Events in the Coronary Tree) study, using 3-vessel radiofrequency intravascular ultrasound, we analyzed the incidence of NCL-MACE in 2 propensity-matched groups according to the presence of DM and TCFA. Results Among 697 patients, 119 (17.7%) had DM. The 3-year total MACE rate (29.4% vs. 18.8%; p = 0.01) was significantly higher in patients with versus without DM, driven by a higher rate of NCL-MACE in DM (18.7% vs. 10.4%; p = 0.02). Propensity score matching generated 2 balanced groups with and without DM of 82 patients each. Among DM patients, the presence of ≥1 TCFA was associated with higher NCL-MACE at 3 years (27.8% vs. 8.9% in patients without a TCFA, hazard ratio: 3.56; 95% confidence interval: 0.98 to 12.96; p = 0.04). DM patients without a TCFA had a similar 3-year rate of NCL-MACE as patients without DM (8.9% vs. 8.9%; hazard ratio: 1.09; 95% confidence interval: 0.27 to 4.41; p = 0.90). Conclusions ACS patients with DM and ≥1 TCFA have a high rate of NCL-MACE at 3 years. In contrast, the prognosis of ACS patients with DM but no TCFAs is favorable and similar to patients without DM.