Feasibility and safety of non-occlusive coronary angioscopic observation using a 4 Fr guiding catheter

Coronary angioscopy (CAS) is a robust imaging methodology for evaluation of vascular healing response after stenting. However, the procedure requires a guiding catheter with a diameter of more than 6 Fr, which is rather invasive at follow-up angiography. Recently, coronary angioscopes of a smaller diameter have been able to pass through a 4 Fr guiding catheter. This study aimed to investigate the feasibility and safety of slender CAS observation using a 4 Fr guiding catheter. Thirty-three consecutive patients who underwent follow-up angiography were evaluated. Following usual angiography via the radial artery, the stent segment was observed by non-occlusive CAS through a 4 Fr guiding catheter. Low molecular weight dextran-L (4 mL/sec) was flushed from a guiding catheter to replace coronary blood. The success rate, anatomical or procedural factors related to the success, and incidence of adverse events were examined. The success rate was 84.8% (n=28/33). The luminal diameter at the orifice of the target vessel was larger in the successful than in the failed group (4.03±0.61 mm vs. 3.39±0.61 mm, respectively; p=0.009). The presence of deep engagement of the guiding catheter into the target vessel was a key factor for sufficient observation (100% in the successful group vs. 0% in the failed group; p