Adenosine Contrast Correlations in Evaluating Revascularization: The (ACCELERATION) Study

Injection of contrast media for rapid measurement of contrast fractional flow reserve (cFFR) obviates the side effects and time requirements of adenosine fractional flow reserve (aFFR) and improves diagnostic performance relative to nonhyperemic pressure ratios. However, studies of cFFR have had variable delivery of contrast. We evaluated the diagnostic performance of cFFR using an automated contrast injector with a standardized volume and rate of delivery of contrast to the reference standard aFFR.

The ACCELERATION study (Adenosine Contrast Correlations in Evaluating Revascularization) is an investigator-initiated, multicenter, prospective, single-arm trial conducted in 5 sites across the United States. cFFR and aFFR were measured in patients with stable coronary artery disease and intermediate stenosis (40% to 70%) using the ACIST CVi automated contrast injector (iopamidol; left coronary: rate of 4 mL/s, volume of 10 cm³ and right coronary: rate of 3 mL/s, volume of 6 cm³) and RXi/Navvus FFR microcatheter. The diagnostic performance of cFFR was assessed using a 0.83 cutoff value based on published literature. Optimal cFFR cutoffs were also determined and illustrated using Bland-Altman analysis.

A total of 192 lesions from 178 patients were included in the per-protocol analysis (69 with an aFFR ≤0.80 and 109 with an aFFR >0.80). Using a cFFR cutoff value of ≤0.83, the accuracy, sensitivity, and specificity of cFFR were 0.89 (95% CI, 0.83-0.93), 0.70 (95% CI, 0.58-0.81), and 0.99 (95% CI, 0.95-1.00), respectively. The mean difference between cFFR and aFFR was 0.05 (-0.04 to 0.13). A cFFR threshold of ≤0.85 had the highest accuracy in predicting aFFR ≤0.80 with accuracy, sensitivity, and specificity equaling 0.90 (95% CI, 0.84-0.94), 0.87 (95% CI, 0.77-0.94), and 0.91 (95% CI, 0.84-0.95), respectively.

cFFR utilizing standardized parameters for contrast delivery leads to clinically acceptable levels of diagnostic performance compared with traditional aFFR to identify physiologically significant intermediate lesions. Future data evaluating the impact on clinical outcomes of cFFR-guided percutaneous coronary intervention are warranted.

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03557385.