Fractional flow reserve (FFR) is an established invasive method for assessing the physiological significance of coronary artery stenosis. However, in recent studies it has been observed and reported some degree of variation in the fraction of the coronary artery to the aortic pressure (Pd / Pa) during the infusion of standard adenosine dose (140mg/kg/min). The observed variation may be attributed to a failure to achieve maximal hyperemia with the normal dose. The administration of adenosine at a higher dose (200μg/kg /min) may influence coronary flow reserve (FFR) eliminating Pd / Pa variation during adenosine infusion.

This is a prospective study which will be conducted in patients after coronary angiography with at least one angiographic lesion ≥50% in coronary vessels.

Patients after written consent will undergo assessment of lesion severity with FFR under a three-minute infusion of adenosine 140mg/kg/min. In patients during steady state hyperaemia (determined by visual assessment) exhibiting variation in Pd / Pa ratio ≥ 0.05 (e.g. difference of max Pd/Pa minus min Pd/Pa) the examination will be repeated after 5 min with three-minute infusion under high dose adenosine (200mg/kg/min). The minimum ratio Pd/Pa per 3 beats will be offline analyzed. The FFR during steady hyperemia state is defined as the average of the minimum ratio Pd / Pa per three beats.

Inclusion Criteria:

1. Age 18-80 years
2. Patients with at least 1 ≥50% stenosis in a coronary vessel, subjected to FFR assessment, who exhibit variation in Pd / Pa ratio ≥ 0.05 (e.g. difference of max Pd/Pa minus min Pd/Pa) during steady state hyperaemia (determined by visual assessment).
3. Written informed consent

Exclusion Criteria:

1. Left main disease (angiographically> 50%)
2. Cardiogenic shock / hemodynamic instability
3. Previous CABG
4. Increased risk of bradycardia on investigator clinical judgment
5. Severe chronic obstructive pulmonary disease
6. Coronary vessels with tortuosity or extremely calcified
7. Severe left ventricular hypertrophy or severe valvular disease
8. STEMI or non-STEMI within the past five days
9. Previous myocardial infarction in the distribution of the target vessel for the FFR
10. Acute decompensated heart failure.