Research On The Influence Of Different Doses Of Nicorandil On Fractional Flow Reserve

Objective:Maximal hyperemia is a prerequisite to evaluate fractional flow reserve?FFR?and adenosine or adenosine triphosphate?ATP?is the most commonly used agent.Infusion of adenosine or ATP can cause chest discomfort,dyspnea and arrhythmia,therefore,an efficient and safe method to achieve hyperemia for evaluating FFR yet to be discovered.Some reports said intracoronary infusion nicorandil can be used for evaluating FFR.The aim of this study was to evaluate the feasibility and safety of intracoronary nicorandil infusion for invasive physiological studies,and the appropriate dose of nicorandil.Method:A total of 26 patients with 30 intermediate lesions?diameter stenosis >40%and <70% by angiography?were enrolled.All vessels underwent FFR measurements with both ATP(150ug/kg·min^-1)and nicorandil?2.0mg,3.0mg and 4.0mg?stimulus.Index of microcirculatory resistance?IMR?was also measured in 14 vessels.Differences with two different methods of hyperemia were assessed by the paired t-test.Differences with three or more different methods were analysed by one-way ANOVA.Results : FFR with different methods of hyperemia had no significant difference?P>0.05?.FFR with nicorandil 3mg IC bolus were most similar to the FFR with ATP I.V.infusion.In 6?20.0%?lesions,FFR with nicorandil 4mg IC bolus exceeded the FFR with ATP infusion,and 13?43.3%?vice versa.In lesions evaluating with nicorandil 3mg,these two data were 14?46.7%?and 8?26.7%?.In 2 lesions,FFR with nicorandil 2mg IC bolus exceeded the FFR with ATP infusion by ?0.05,and none appeared when use higher doses nicorandil as hyperemia agent.The IMR was 29.80±18.09 with i.v.ATP and 25.21±9.73 with IC nicorandil.The time to the lowest FFR was shorter with IC infusion of nicorandil than with i.v.infusion of ATP,and had significant difference?all P<0.01?.An IC infusion of nicorandil 4mg could achieve longest plateau time than IC infusion of nicorandil 3mg or 2mg?39.43±13.45:32.93±12.39:24.53±12.24?.IC infusion of nicorandil produced fewer changes in the heart rate than an i.v.infusion of ATP?P<0.05?.However,an IC infusion of nicorandil 4mg would cause mean blood pressure reducing more significant than ATP i.v.infusion?P<0.05?.27?90.0%?patients felt chest discomfort or dyspnea with ATP i.v.infusion,and none with nicorandil IC infusion.Transient AV block were not occurred in patients with different methods of hyperemia.A female patient occurred hypotension during ATP i.v.infusion.1 patient had a headache for a few hours.Conclusion:This study suggests that nicorandil intracoronary infusion is a simple,safe and efficient method to induce hyperemia for evaluate fractional flow reserve.Taking into account factors such as maintaining the plateau time and the effectiveness of hyperemia,an intracoronary infusion of nicorandil 3mg is more suitable to induce hyperemia for evaluating fractional flow reserve and index of microcirculatory resistance.