Objectives At present, adenosine (AD) is the most widely used agents in fractional flow reserve (FFR) measurement but has the disadvantages of higher rate of complications including atrioventricular block. So it’s necessary to explore other stimulus equivalent to or better than AD in effects on FFR measurement with less complications and lower costs.
Methods In 40 patients with 53 moderate coronary stenosis, intracoronary (IC) AD in 2 serial doses (A1: 40 μg; A2: 60 μg) was administered in the standard bolus to calculate FFR, followed by a repeat FFR measurement with IC Sodium Nitroprusside (SNP) in 3 serial doses (S1: 0.3 μg/kg; S2: 0.6 μg/kg; S3: 0.9 μg/kg).
Results 1) Target lesions were located in the left anterior descending (n = 24), left circumflex (n = 13) and right coronary artery (n = 16). The mean stenosis rate was 62.8 ± 8.6%. 2) FFR value decreased significantly from 0.90 ± 0.05 at baseline to 0.83 ± 0.06, 0.82 ± 0.07, 0.83 ± 0.07, 0.81 ± 0.07 and 0.81 ± 0.07 in A1, A2, S1, S2 and S3 (F = 16.877, P < 0.001). 3) Systolic blood pressure decreased by 3.99%, 6.64%, 6.87%, 10.56% and 15.55% in A1, A2, S1, S2 and S3. 4) Heart rate was increased by 2.01%, 0.84%, 1.23%, 1.34% and 3.11% in A1, A2, S1, S2 and S3. 5) The mean time to peak value of FFR delayed in S1, S2 and S3 compared with A2 (F = 15.593, P < 0.001). 6) The mean duration of the plateau phase was longer in S1, S2 and S3 compared with A2 (F = 34.445,P < 0.001), and longer in S3 than S1 (F = 7.392, P = 0.008). 7) Immediate complications occurred in 15.1% of patients, including transient atrioventricular block (6 patients), chest pain (1 patient) and stomach ache (1 patient) after the 60 μg dose of IC AD bolus was administered. No adverse events were found after 3 serial of doses IC SNP were used. (X2 = 8.171, P = 0.004).
Conclusions Compared with IC AD, IC SNP has equivalent effects on FFR measurement as well as the advantage of lower rate of complications and cost. But duration of the plateau phase by IC SNP is twice as much by IC AD, and time to peak FFR value was delayed 50%.