A randomised comparison of the use of 4 and 6 French diagnostic catheters: the limits of downsizing.

BACKGROUND: The use of small catheters for coronary angiography can reduce the risk of vascular complications and allow early ambulation, but excessive downsizing may lead to poor quality imaging. The aim of this study was to assess the feasibility of performing coronary angiography using 4 French (4 F) femoral catheters. METHODS: In total, 400 consecutive elective patients were randomised to undergo coronary angiography with 4 F or 6 F catheters. The puncture site was manually compressed and inspected before and after ambulation, and 24 h later. The handling difficulty of the catheters was semi-quantitatively evaluated using a three grade scoring system; angiogram quality was evaluated by two independent physicians. RESULTS: No major procedure-related complications were observed. Coronary arteriography with 4 F catheters was possible in all of the attempted cases. There were no statistical differences between the two groups in terms of procedural or fluoroscopy time, the amount of contrast medium used, or the incidence of vascular complications, while compression time was significantly shorter in the patients studied using the smaller catheter (3.4 vs. 9.9 min; P<0.0001). Catheter stability was similar in the two groups, whereas catheter torque and the quality of the coronary angiograms were statistically better in the patients studied using six French catheters. CONCLUSIONS: Coronary angiography with 4 F catheters is technically feasible and permits early ambulation after the procedure. Although the radiological resolution of the images obtained using 4 F catheters was always adequate for clinical decision-making, the angiogram quality and catheter handling were significantly better using the 6 F system.