Feasibility of intracoronary nicorandil for inducing hyperemia on fractional flow reserve measurement: Comparison with intracoronary papaverine.

BACKGROUND

Adenosine and adenosine triphosphate (ATP) are widely used to induce hyperemia for fractional flow reserve (FFR) measurements. Caffeine attenuates their hyperemic effects, but not those of nicorandil and papaverine. No studies have systematically compared the hyperemic efficacies of nicorandil, papaverine, and ATP with and without caffeine abstention.

METHODS

FFRs were measured using nicorandil 2 mg (FFRNC2), nicorandil 4 mg (FFRNC4), and papaverine (FFRPAP) in 40 patients (group 1), and using nicorandil 2 mg, ATP (FFRATP), ATP plus nicorandil (FFRATP+NC2), and papaverine in 20 patients with (group 2) and in 20 patients without caffeine abstention (group 3).

RESULTS

In group 1, FFRNC2 and FFRNC4 did not differ (p = 0.321) and were higher than FFRPAP (p < 0.001 and p = 0.0026). Likewise, FFRNC2 was higher than FFRPAP in groups 2 (p = 0.049) and 3 (p < 0.010). In the whole group, Bland-Altman analysis showed a modest mean difference (0.015, p < 0.001) and narrow 95% limits of agreement (-0.025 and 0.056). FFRNC2 and FFRPAP strongly correlated (r = 0.975, p < 0.001). Compared with FFRPAP, FFRATP and FFRATP+NC2 did not differ in group 2 (p = 1.0 and p = 0.780), but they were higher (p = 0.002 and p = 0.02) in group 3. Adjunctive nicorandil did not decline FFR further in groups 2 (p = 0.942) and 3 (p = 0.294).

CONCLUSIONS

Nicorandil 2 mg is a safe and practical alternative for patients who consume caffeine-containing products before the test or have contraindications for adenosine/ATP. Increasing the nicorandil dose to 4 mg or administering adjunctive nicorandil during ATP infusions does not offer any clinical advantages compared with administering nicorandil 2 mg alone.