DIFFERENCES IN ADENOSINE INDUCIBLE MAXIMAL CORONARY
HYPERAEMIA FOR FRACTIONAL FLOW RESERVE MEASUREMENTS. R.J.
Whitbourn*, A. Jeremias, S.D. Filardo, P.J. Fitzgerald, A.C. Yeung, P.G. Yock. Departments of
Cardiology, St Vincent's Hospital Melbourne* and Stanford University, USA. Fractional flow reserve (FFR) has been shown to reliably
indicate coronary stenosis severity and requires intracoronary pressure
measurements to be obtained at maximal hyperaemia. The most widely used approached to induce maximal coronary
hyperaemia employ adenosine, administered either as a continuous intravenous (I.V.) infusion or intracoronary (I.C.)
bolus. Objectives: We set
out to compare the efficacy of I.V. to I.C. adenosine administration for the
measurement of the pressure-derived FFR.
Methods: In a
multi-center trial, 52 patients with 60 lesions underwent determination of FFR
using both I.V. and I.C. adenosine. I.V. adenosine was administered as a
continuous infusion at a rate of 140mg/Kg/min to achieve steady state hyperaemia. I.C.
adenosine boluses were administered 15-20mg in the right and 18-24mg in
the left coronary artery. FFR was
calculated as the ratio of the distal coronary pressure to the aortic pressure
at hyperaemia. Results: A total of 60 stenoses were evaluated. Mean percent stenosis for both groups was
55.8 ± 23.6% (range 0 - 95%) and mean FFR was 0.78 ± 0.15 (range 0.41 -
0.98). There was a strong and linear
correlation between FFR measurements with I.V. and I.C. adenosine (R=0.978,
y=0.032 ± 0.965x, p<0.001). The agreement between the two sets of
measurements was also high with a mean difference in FFR of -0.004 ± 0.03. However, in 5 lesions (8.3%) FFR with I.C.
adenosine was higher by 0.05 or more compared to I.V. infusions, suggesting a
suboptimal hyperaemic response in these patients. Changes in heart rate and
blood pressure were significantly higher with I.V. adenosine. Two patients with
I.V. - but none with I.C. adenosine - had severe side effects (bronchospasm and
severe nausea). Conclusion: The
results suggest that I.C. adenosine is equivalent to I.V. infusion for the
determination of FFR in >90% of patients.
When FFR, using I.C. adenosine, is within 0.05 of the accepted ischemic
threshold (0,75), rechallenge of maximal hyperaemia should be performed with
I.V. adenosine.
