Material and Method: The data were collected retrospectively of all patients that received cardiac catheterization at Thammasat University Cardiac Center between September 1, 2010 and August 31, 2011 (the first year of TR approach).

Results: Cardiac catheterization was performed on 597 patients. TR approach was performed about one-sixth of all procedures compared to conventional TF approach, 93 (15.58%) vs. 504 (84.42%). Safety of TR approach at the beginning was similar to conventional TF approach including in-hospital complication rate 5.4% vs. 4.6%, p = 0.788, volume of contrast media used 90.63±66.83 vs. 97.89±64.52 milliliters, p = 0.323, radiation exposure defined as median/min-max estimate skin entrance radiation dose 833.35/133.15-8,913.42 vs. 910.00/76.78-13,719.88 mGy, p = 0.599, and dose-area product 63.03/7.87-494.52 vs. 70.85/5.77-829.16 Gy x cm2, p = 0.586. The efficacy defined as procedural success rate was significantly higher in the conventional TF approach 90.3% vs. 97.8%, p = 0.001, as well as the procedural time that showed insignificantly longer 54.03±39.40 vs. 47.37±39.86 minutes, p = 0.139. This statistical difference in the procedural success rate was clear only in the first 62 TR. After this learning curve period, the procedural success rate was similar, 96.8% vs. 97.6%, p = 0.575. Both the procedural success rate and the procedural time in TR approach showed trend to achieve better outcomes according to the increasing number of TR procedures; 87.1% vs. 87.1% vs. 96.8%, p = 0.331 and 64.68±51.90 vs. 52.45±31.94 vs. 44.97±29.04 minutes, p = 0.139 in the first 31 vs. the 32nd to the 62nd, and the 63rd to the 93rd cases respectively.

Conclusion: The safety of the transradial approach for cardiac catheterization procedures was similar to conventional transfemoral approach. The learning curve period was needed but its length is acceptable before the same efficacy rate as the conventional transfemoral procedure was achieved.

Keywords: Learning curve, Transradial (TR) cardiac catheterization