Functional assessment of intermediate coronary artery stenosis with 4-Fr catheters

The 4-Fr catheter system is not recommended for invasive functional assessment of coronary artery stenosis, because it tends to distort the aortic waveform. This study aimed to identify the incidence of aortic waveform distortion and a feasible method for correct diagnosis of coronary artery stenosis with a 4-Fr catheter. We retrospectively investigated 178 lesions with intermediate coronary artery stenosis. Non-hyperemic distal coronary artery pressure (Pd) and aortic pressure (Pa) were measured with a 4-Fr diagnostic or 6-Fr guiding catheter before and after saline flush. The mean Pd/mean Pa (Pd/Pa) and instantaneous wave-free ratio (iFR) were calculated before and after flushing. We compared the effect of flushing on the changes in Pd/Pa and iFR between the 4-Fr diagnostic and 6-Fr guiding catheters. Using the 4-Fr diagnostic catheter, there was a significant decrease in incidence of aortic waveform distortion from 42.0% (47 lesions) before flushing to 1.8% (2 lesions) after flushing ( p