Patients presenting with slow flow after PPCI undergo to at least 200 mcg of intracoronary nitroprussiate or 500 mcg of intracoronary adenosine during 2 minutes

Patients presenting with slow flow after PPCI undergo to controlled saline intracoronary infusion by a dedicated microcatheter (RayFlow) at 20 ml/min during 2 minutes

Intracoronary bolus of at least 200 mcg of nitroprussiate or 500 mcg of intracoronary adenosine during 2 minutes. Operators are allowed to combine both drugs.

Cine-fluoroscopic recording of the infarct-related artery (IRA) at 30 frames/second and off-line core-laboratory assessment of the number of cineframes needed for dye to reach standardized distal landmarks is the coprimary endpoint. Long TIMI frame counts are indicative of slow coronary flow. Previous studies showed TIMI frame counts of 30 (SD 12) after nitroprussiate in slow flow STEMI patients. The present study is powered to assess 25 percent difference between study groups (80 percent power and 5 percent alfa error).

MMR is assessed by intracoronary thermodilution with a dedicated pressure wire and microcatheter (RayFlow, Hexacath) during saline infusion at 20 ml/min. MMR is measured offline by the core-laboratory at 20 seconds of the saline infusion in the standard medical treatment group and at 2 minutes and 20 seconds in the experimental group. According to previous studies, MMR was 537 Wood units (SD 289). The present study is powered to assess 30 percent difference between study groups after study intervention (80 percent power and 5 percent alfa error).

Experimental treatment with saline infusion via microcatheter is performed continuously recording the pressure and temperature values of the culprit artery. Off-line core-laboratory assessment of the MMR will be performed at 20 seconds and at 2 minutes of the saline infusion.

Absolute coronary flow is performed simultaneously with the MMR. This value shows the coronary blood flow of the culprit artery during maximal hyperemia.