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 nicorandil (NIC) compared with that of papaverine (PAP) in the evaluation of coronary flow reserve (CFR) in 17 patients, including 10 patients with old myocardial infarction and 7 patients with angina pectoris. CFR was measured with a Doppler guidewire inserted into the distal site of the left anterior descending coronary artery during intracoronary administration of 10 mg PAP, and of 0.5 mg, 1.0 mg, 2.0mg, and 3.0 mg NIC. We examined the changes in heart rate (HR), mean blood pressure (mBP), the total score of QTc interval on a 12-lead electrocardiogram (∑ QTc), and ST-T segment, before and after drug administration. CFR was significantly lower during administration of 0.5 mg (1.9 ± 0.9) and 1.0 mg (2.2 ± 0.9) NIC than during administration of PAP (2.6 ± 1.1) (P < 0.01). There was no significant difference in the CFR during administration of 2.0 mg (2.6 ± 1.0) or 3.0mg (2.5 ± 1.0) NIC and that observed during administration of PAP. The CFR during administration of PAP was significantly correlated with that during administration of 2.0 mg NIC (r 2 = 0.72, P < 0.0001) and 3.0mg NIC (r 2 = 0.70, P < 0.0001). PAP, but not NIC, significantly altered the HR, mBP, and ∑ QTc. Inverted T waves were observed in 14 patients, and elevation of the ST segment was observed in 4 patients during administration of PAP (including 1 patient with ventricular tachycardia). The administration of 0.5 mg to 2.0 mg NIC was not associated with ST-T segment changes, except in 1 patient, but inverted T waves were observed in 2 patients and depression of the ST segment was observed in 2 patients during administration of 3.0mg NIC. Intracoronary administration of NIC is useful and safe for evaluating the CFR. The appropriate dose for measuring CFR is 2.0 mg nicorandil.