Coronary Flow Reserve by Contrast-Enhanced Echocardiography: A New Noninvasive Diagnostic Tool for Cardiac Allograft Vasculopathy

Abstract

Noninvasive tests have proven unsatisfactory in cardiac allograft vasculopathy (CAV) diagnosis. We assessed coronary flow reserve (CFR) by contrast-enhanced transthoracic echocardiography (CE-TTE) in heart transplantation (HT). CFR was assessed in the left anterior descending coronary artery in 73 HT recipients (59 male, aged 50 ± 12 years at HT), at 8 ± 4.5 years post-HT. CFR measurements were taken blindly from coronary angiographies. CFR cut points were the standard value of ≤2 and those defined by receiver operating characteristics (ROC) curve analysis. CFR was lower in patients with CAV (2.3 ± 0.7 vs. 3.2 ± 0.5, p < 0.0001). The ≤2 cut point was 100% specific and 38% sensitive. The ≤2.7 cut point, optimal by ROC analysis, was 87% specific and 82% sensitive. Accuracy rose from 71% with the standard ≤2 cut point to 85% with the optimal cut point of ≤2.7. CFR by CE-TTE may offer promise as a novel, easily repeatable and accurate noninvasive tool in CAV detection. However, further longitudinal studies in larger patient cohorts are warranted before widespread adoption can be advocated. Noninvasive tests have proven unsatisfactory in cardiac allograft vasculopathy (CAV) diagnosis. We assessed coronary flow reserve (CFR) by contrast-enhanced transthoracic echocardiography (CE-TTE) in heart transplantation (HT). CFR was assessed in the left anterior descending coronary artery in 73 HT recipients (59 male, aged 50 ± 12 years at HT), at 8 ± 4.5 years post-HT. CFR measurements were taken blindly from coronary angiographies. CFR cut points were the standard value of ≤2 and those defined by receiver operating characteristics (ROC) curve analysis. CFR was lower in patients with CAV (2.3 ± 0.7 vs. 3.2 ± 0.5, p < 0.0001). The ≤2 cut point was 100% specific and 38% sensitive. The ≤2.7 cut point, optimal by ROC analysis, was 87% specific and 82% sensitive. Accuracy rose from 71% with the standard ≤2 cut point to 85% with the optimal cut point of ≤2.7. CFR by CE-TTE may offer promise as a novel, easily repeatable and accurate noninvasive tool in CAV detection. However, further longitudinal studies in larger patient cohorts are warranted before widespread adoption can be advocated.