Intracoronary nicorandil induced hyperemia for physiological assessments in the coronary artery lesions

OBJECTIVE: Maximal hyperemia is a key element of invasive physiological examination. The aim of this study was to investigate the efficacy and safety of intracoronary (IC) nicorandil in comparison with adenosine 5′-triphosphate (ATP) intravenous (i.v.) injection for fractional flow reserve (FFR) measurement in coronary artery lesions. MATERIALS AND METHODS: In this study, 46 patients who had their FFR measured were enrolled, including 51 lesions. Hyperemia was induced by bolus 2 mg nicorandil and ATP (40 mg ATP + 36 ml saline, weight × 10 ml/h) for FFR measurement. The safety and efficacy of IC nicorandil were evaluated. RESULTS: The mean FFR values measured by nicorandil and ATP were 0.810 ± 0.013 and 0.799 ± 0.099, p < 0.001, respectively. There was a strong correlation between FFR measured by nicorandil and ATP (r = 0.983, R(2) = 0.966, FFR(nicorandil) = 0.937 × FFR(ATP) + 0.061). The rate of FFR ≤ 0.75 in the nicorandil and ATP groups was 31.37 vs. 35.29%, respectively (p = 0.841), the consistency rate was 96.08%; the FFR ≤ 0.8 rate was 41.18 and 43.14%, respectively (p = 0.674), and the consistency rate was 90.20%. In five lesions, the FFR value measured by nicorandil ranged between 0.79 and 0.82, indicating inconsistency according to FFR ≤ 0.8. The blood pressure changes caused by nicorandil and ATP were 12.96 ± 6.83 and 22.22 ± 11.44 mmHg (p < 0.001); the heart rate changes were 2.43 ± 1.31 and 6.52 ± 2.87 beats/min, respectively (p < 0.001); and the PR interval changes were 6.0 (1.0–11.0) and 9.0 (2.0–19.0) ms, respectively (p < 0.001). Visual analog scale (VAS) scores in the nicorandil group were all in the range 0–2, while in the ATP group were mostly in the range of 3–5. CONCLUSION: Intracoronary bolus of nicorandil (2 mg) infusion induces stable hyperemia, and it could be considered as an alternative drug to ATP for FFR measurement with a lower side effect profile in most patients.