WASHINGTON (FRONTLINE MEDICAL NEWS) – Coronary catheterization procedures done via transradial access produce significantly better patient outcomes, compared with transfemoral approaches, but transradial also leads to substantially higher radiation exposure to the operator, according to an analysis of 650 procedures.

When operators performed transradial coronary catheterizations they received on average nearly twice the radiation dose to their chest as they did when they performed transfemoral procedures, in a randomized trial that included 14 interventional cardiologists, Alessandro Sciahbasi, MD, reported at the annual meeting of the American College of Cardiology.

The average difference in normalized, effective radiation exposure in the thorax – 1.1 mcSv per procedure – meant that for every 100 catheterizations performed transradially, the operator would receive an excess radiation dose nearly equal to six chest x-rays, compared with performing the same procedures transfemorally, said Dr. Sciahbasi, an interventional cardiologist at Sandro Pertini Hospital in Rome. Because study results have proven that transradial access results in superior patient outcomes to transfemoral, the solution is not to abandon the transradial approach, but to encourage operators to “reduce radiation doses and adopt adjunctive radiation protection,” he said. “We have methods available to reduce radiation exposure.”

Radiation exposures to the operators’ wrists and eyes showed no significant differences between the two catheterization routes. The difference was limited to thorax exposure.

“These data worry me,” commented Sunil V. Rao, MD , a long-time advocate for increased transradial catheterizations in U.S. practice. “We are pretty obsessive about radiation detection in our catheterization laboratory,” said Dr. Rao, an interventional cardiologist at Duke University in Durham, N.C.

Dr. Sciahbasi and his associates from the MATRIX (Minimizing Adverse Haemorrhagic Events by Transradial Access Site and Systemic Implementation of angioX) trial, ran the Radiation Dose-Matrix ( RAD MATRIX ) substudy using a subgroup of participating operators and their patients. The full MATRIX trial compared outcomes in 8,404 patients randomized to transradial or transfemoral access and helped establish that transradial procedures led to significantly reduced rates of major bleeds and all-cause mortality (Lancet. 2015 Jun 20; 385[9986]:2465-76 ).

The RAD-MATRIX substudy focused on the radiation exposures received by 14 participating operators who wore radiation dosimeters on their wrist, chest, and near their eyes during each procedure. All operators performed both transradial and transfemoral catheterizations with the choice dictated by the randomization protocol. The transradial procedures underwent further randomization to access through either the patient’s left or right arm. The full analysis included 398 procedures performed by transfemoral access, and 252 with transradial access with 131 via the left forearm and 121 via the right forearm.

The analysis showed that, when the operators performed transradial catheterizations, they received an average, normalized, effective dose to their thorax of 2.3 mcSv per procedure and 1.2 mcSv when performing transfemoral catheterization, a statistically significant difference. The exposures from left and from right transradial access did not differ significantly. Concurrently with Dr. Sciahbasi’s report at the meeting the results also appeared in an online article (J Am Coll Card. 2017 Mar 18. doi: 10.1016/j.jacc.2017.03.018 ).

The analysis also showed a 10-fold variability in exposure level among the 14 participating operators. Dr. Sciahbasi hypothesized that this reflected substantive differences in the degree of radiation protection used by each operator and suggested this implied that some interventionalists were not protecting themselves from exposure as thoroughly as possible.

RAD-MATRIX received partial funding from The Medicines Company and Terumo. Dr. Sciahbasi had no disclosures. Dr. Rao has been a consultant to Boehringer Ingelheim, Cardinal Health, Corindus, Cardiovascular Systems, and Medtronic.

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