Abstract 2582: Coronary Flow Reserve by Contrast-Enhanced Transthoracic Echocardiography Predicts Cardiac Allograft Vasculopathy Onset in Heart Transplant Patients With Normal Coronary Angiogram
Background: Cardiac allograft vasculopathy (CAV) is the leading cause of late mortality after heart transplantation (HT). We assessed the validity of coronary flow reserve (CFR) by contrast-enhanced transthoracic echocardiography (CE-TTE) as a predictor of CAV onset in HT patients with normal coronary angiograms.
Methods: CFR were measured in the left anterior descending coronary artery (LAD) by CE-TTE in 30 HT patients (pts) (19 M, aged 49 ± 13 years at HT, follow up 7.2 ± 4.7 years) with normal coronary angiography. Coronary flow velocity in the LAD was detected at rest and during adenosine infusion. CFR was obtained as the ratio of hyperaemic diastolic mean velocity (DMV) to resting DMV. Coronary angiography was repeated after 24 ± 7 months. Angiographies were analyzed using a qualitative grading system: grade I, normal angiogram; II, luminal irregularities, diameter reduction <30%; III, stenosis <50% and grade IV, stenosis ≥50% and/or diffuse narrowing of small vessels. CAV onset was defined as angiographic changes ≥ grade II.
Results: CFR was 3 ± 0.7. CAV onset was present in 5 pts (17%) (grade II in 2, grade III in 2 and grade IV in 1 patient). CFR was lower in pts with CAV onset (3.2 ± 0.7 vs 2.1 ± 0.5, p=0.009). A ROC-derived CFR cutpoint of ≤ 2.4 (AUC 0.912, p=0.004) was 88% specific and 80% sensitive for predicting CAV onset, (PPV= 57%, NPV=95%) (p=0.001). Pts with CFR ≤ 2.4 had a lower survival free from CAV onset (42% vs 96%, p=0.005) (Figure⇓). By Cox regression a lower CFR predicted CAV onset (RR 6.2, 95% CI 1.5–26.3, p=0.01).
Conclusions: CE-TTE assessment reveals that lower CFR is a reliable predictor of CAV onset in HT pts with normal coronary angiograms.