Coronary plaque composition assessed by intravascular ultrasound virtual histology: association with long-term clinical outcomes after heart transplantation in young adult recipients.

OBJECTIVES

To assess coronary plaque composition by virtual histology intravascular ultrasound (VH-IVUS) analysis in young adult recipients and to correlate these findings with time from heart transplant (HTx) and long-term outcomes.

BACKGROUND

Rapid progression of coronary allograft vasculopathy after heart transplantation is a powerful predictor of mortality and clinical events at long-term.

METHODS

Forty consecutive young adult recipients transplanted during childhood undergoing VH-IVUS during coronary surveillance have been prospectively included in this study. According to the time interval from HTx to VH-IVUS assessment, our cohort was divided into two groups (group A: ≤5 years, n = 13; group B: >5 years, n = 27).

RESULTS

Group B showed an higher percentage of necrotic core and dense calcium (12 ± 2 vs. 5 ± 1%, P = 0.04; 8.2 vs. 2.1%, P = 0.03; respectively). An "inflammatory plaque" (necrotic core and dense calcium ≥30%) was detected in 34.8% of patients in group B and in none among group A patients (P = 0.03). Patients in group B had a number of adverse clinical events significantly higher than group A patients (53.8 vs. 14.3%; HR 4.45; 95% CI 1.62-12.16; P = 0.029) at long-term follow-up (4.2 years). The multivariate regression analysis showed that age (HR 1.5; 95% CI 1.1-2.0; P = 0.007), time from HTx (HR 1.8; 95% CI 1.6-4.8; P = 0.02), and inflammatory plaque (HR 2.4; 95% CI 1.1-5.3; P = 0.03) were independent predictors of adverse clinical events.

CONCLUSIONS

This study supports the hypothesis that time-dependent differences in plaque composition, as assessed by VH-IVUS, occur after HTx in young adult recipients, probably determining an increased risk of long-term clinical events.