LAS VEGAS—While higher failure rates with transradial PCI are clearly aligned with lower operator volumes, Christopher T. Pyne, MD, of the Lahey Clinic in Burlington, Mass., suggested that switching sides of the transradial is a better bailout strategy than “going femoral,” during a May 9 presentation at the 35th annual meeting of the Society for Cardiovascular Angiography and Interventions (SCAI).
Failure rate is volume dependent, Pyne stated. Generally failure rates settle in the 1 to 3 percent range in most registries (Circ Cardio Interv 2011:4:336-341). Initially, when an operator is starting out, the failure rates can be as high as 10 to 15 percent, but with experience, they typically drop to the lower single-digit range.
Pyne also looked at failure rates when the operator was under pressure, specifically with time-critical STEMI patients. “There is a large range of failure rates in randomized controlled trials, and in the larger trials, such as RIVAL, the failure rates range from 4.7 to 7.6 percent in these STEMI patients,” he said. In RIVAL, which had highly skilled operators, the failure rate was 4.5 percent in the overall cohort.
“It’s not surprising that the failure rates are higher in STEMIs because of hypotension, high catecholamine states and impatience with anomalies,” Pyne noted. “Even if the radial approach is successful about 5 to 7 percent of the cases will need additional femoral support.”
Operators, particularly new operators, tend to struggle with spasms, subclavian tortuosity and the radial loop. “All of these causes tend to be equal contributors, so one does not dominate the reasons for failure,” Pyne said. Also, approximately 40 percent of transradial failures for new operators are side specific, he added.
Of course, technique will matter as well. Failure from puncture can be diminished if an operator gets particularly skilled in either of the techniques— the Seldinger (ball wall puncture) technique or the one wall technique. However, there has been no definitive answer as to which is better, according to Pyne.
Thus, one recent study, currently in press in Catheterization & Cardiovascular Interventions, evaluated reducing bailouts from bailout puncture in 412 cases with experienced operators through the Seldinger technique or the one wall technique. The researchers found that access times and procedure times were shorter when the Seldinger technique was used. Also, failure to access was zero with this technique, as opposed to 11 percent with the one wall technique.
Failures from radial loop occur in 1 to 2 percent of cases, and occurrences are not predictable, size specific or mirrored from one side to the other. However, severity, caliber and size of branches will dictate success, said Pyne, who recommended a bailout strategy of using the opposite side.
Failures from spasm are more common in females, with small radial arteries, in patients with diabetes and a failed first puncture. While operator volume can help recognize these issues earlier, the bailout strategy is to use vasodilators, smaller catheters and to allow time to let the spasm relax.
Failure from subclavian tortuosity can be predicted by advanced age, short stature and the female sex. This also occurs two to three times more common on the right than the left side, so Pyne again recommended moving to the opposite side. “With these predictive factors, operators may want to consider starting from the left at the very beginning,” he said.
In general, operators also can reduce need for bailout using clinical predictors. “You are more likely to fail in older, smaller, shorter (less than 5’5") and female patients, but these also are the cases that receive the most significantly, positive impact from the transradial approach, including a mortality benefit,” Pyne said.
To evaluate the current practices of transradial bailouts, Betrand et al conducted an international survey, which found that 55 percent of operators resort to the femoral approach after a failure, and only about 30 percent move to the opposite radial artery (JACC Cardiovasc Interv 2010;3(10):1022-1031).
During his presentation, Pyne was advocating to buck that trend. “I recommend switching first, as opposed to bailing out completely on the radial approach,” said Pyne, adding that approximately half of all failures are side specific.