Initial Intravascular Ultrasound Without a Routine Early Baseline Study in the Evaluation of Cardiac Transplant Vasculopathy has Prognostic Valve

Background: Abnormal minimal intimal thickening (MIT) on intravascular ultrasound (IVUS) defined as difference of ≥0.5 mm between baseline and one-year post-transplantation has been shown to have prognostic value. The goal of this retrospective cohort study was to evaluate whether abnormal MIT found on routine IVUS studies in cardiac transplant patients after 6 months without an early baseline study (modified MIT or MMIT), has any prognostic value. Furthermore, we evaluated the prognostic effect of serial IVUS performed beyond one year. Methods: A cohort of 149 cardiac transplant patients who underwent IVUS examination > 6 months post-transplant were evaluated retrospectively. Of these 149 patients, 109 patients underwent a subsequent IVUS study approximately 1 year following the initial study. MMIT values of ≥0.5 mm without an early baseline study were correlated with major adverse cardiac event (MACE). Results: The all-cause mortality was 4.7% (5/107) in patients with MMIT of <0.5 mm vs. 14.6% (6/41) in patients with MMIT of ≥0.5 mm [hazards ratio (HR): 3.2; 95% confidence interval (CI): 1.002–12.17; p = 0.039]. The overall MACE rate was 8.4% (9/107) in patients with MMIT of <0.5 mm vs. 24.4% (10/41) in patients with MMIT of ≥0.5 mm [HR: 6.7; 95% CI: 1.30–9.42; p = 0.009]. After adjusting for age, abnormal MMIT remained a significant independent predictor of MACE (HR: 3.93; CI 1.21–12.81; p = 0.023). Conclusions: The presence of abnormal MMIT noted on IVUS performed after 6 months post-transplantation without a routine baseline IVUS carries important prognostic value.