Estimation of coronary flow reserve by intracoronary administration of nicorandil: comparison with intracoronary administration of papaverine

We investigated the usefulness of the intracoronary administration of nicor andil (NIC) compared with that of papaverine (PAP) in the evaluation of cor onary flow reserve (CFR) in 17 patients, including 10 patients with old myo cardial infarction and 7 patients with angina pectoris. CFR was measured wi th a Doppler guidewire inserted into the distal site of the left anterior d escending coronary artery during intracoronary administration of 10mg PAP, and of 0.5mg, 1.0mg, 2.0mg, and 3.0mg NIC. We examined the changes in heart rate (HR), mean blood pressure (mBP), the total score of QTc interval on a 12-lead electrocardiogram (Sigma QTc), and ST-T segment, before and after drug administration. CFR was significantly lower during administration of 0 .5mg (1.9 +/- 0.9) and 1.0mg (2.2 +/- 0.9) NIC than during administration o f PAP (2.6 +/- 1.1) (P < 0,01). There was no significant difference in the CFR during administration of 2.0mg (2.6 +/- 1.0) or 3.0 mg (2.5 +/- 1.0) NI C and that observed during administration of PAP. The CFR during administra tion of PAP was significantly correlated with that during administration of 2.0mg NIC (r(2) = 0.72, P < 0.0001) and 3.0 mg NIC (r(2) = 0.70, P < 0.000 1). PAP, but not NIC, significantly altered the HR, mBP, and Sigma QTc. Inv erted T waves were observed in 14 patients, and elevation of the ST segment was observed in 4 patients during administration of PAP (including 1 patie nt with ventricular tachycardia), The administration of 0.5 mg to 2.0mg NIC was not associated with ST-T segment changes, except in 1 patient, but inv erted T waves were observed in 2 patients and depression of the ST segment was observed in 2 patients during administration of 3.0mg NIC, Intracoronar y administration of NIC is useful and safe for evaluating the CFR. The appr opriate dose for measuring CFR is 2.0mg nicorandil.