During the late-breaking trial sessions of the Transcatheter Cardiovascular Therapeutics (TCT) conference on Nov.10, 2011, the attention briefly shifted away from transcatheter aortic valve therapy to focus on one major development in selecting the best access route for percutaneous coronary intervention (PCI).
According to the RIFLE STEACS trial, angioplasty performed via the radial access is associated with less bleeding and cardiovascular mortality than the femoral approach—traditionally the standard access site for interventionalists performing PCI in the United States. Following the announcement of these positive results, many European physicians are calling for a shift of practice away from the femoral approach to the safer and more effective radial approach.
RIFLE STEACS trial demonstrates safety and efficacy of radial approach versus femoral approach
As a multi-center, interventional trial conducted in Italy, the RIFLE STEACS trial studied over 1,001 STEMI patients with STS elevation acute coronary syndrome (STEACS) undergoing primary angioplasty by randomizing patients to either the femoral approach—insertion of the catheter through the groin—or the radial access—insertion of the catheter through the wrist.
Until RIFLE STEACS, other trials only demonstrated equivalence, not superiority of the radial approach. Now, results at 30 days showed that the radial access reduces net adverse events by almost two-fold compared to the femoral access; while 21% of patients undergoing PCI through the transfemoral approach experienced adverse events, only 13.6% of patients receiving the radial approach experienced adverse events.
Furthermore, bleeding was significantly reduced in the radial group compared to the femoral group by over 160%. The bleeding rate for the femoral approach is benchmarked at 12.2% compared to 7.8% for the radial approach, allowing researchers to connect the dots between bleeding rates and cardiovascular mortality in high-risk patients.
In terms of cardiac death, 9.2% of patients treated transfemorally passed away, compared to 5.2% of patients treated transradially. For other outcomes, such as MI, cerebrovascular incidence, and revascularization, results were similar between the two approaches, while the rate for non-access site bleeding was 5.4% for the femoral approach versus 5.2% for the radial approach.
Nevertheless, these positive data revealed that the radial approach is an independent predicator of outcomes, with demonstrated improvement in clinical safety and reduction of mortality over the femoral approach. According to the trial presenter, Enrico Romagnali, MD, radial access should not only be included in future training guidelines, but should be recommended as the preferred approach in treatment guidelines for coronary intervention of STEMI patients.
Despite strong clinical evidence, steep learning curve may challenge future US adoption
On the heels of these positive data, however, the question remains—how can clinical results be translated into reality in the United States?
Compared to significantly higher rates of radial access adoption in Europe, the adoption rate for the radial access is only 11% in the US. According to new study results complementary to RIFLE STEACS, one of the leading drivers of this low acceptance rate is the significant learning curve associated with the radial approach, which may be even steeper than many had expected. Study investigators revealed that outcomes for the radial approach can be correlated with operator experience and the strength of training regimen. Many physicians reported that it may take at least 50 cases to become comfortable with the radial access, while other interventionalists found it difficult to become adept at the radial approach even after 150 cases. Physicians looking to switch from the femoral approach to the radial approach on the heels of strong clinical evidence should therefore take a slow, carefully planned strategy, first performing the procedure on lower risk patients and eventually shifting to the high risk STEMI patient population.
Furthermore, the study shows that the steep learning curve is surmountable, especially if interventionalists are introduced to the radial approach early on in the training process for PCI. One major hurdle with transitioning to the radial approach to PCI is the significantly longer procedural time that the method takes compared to the femoral approach. Nevertheless, anecdotally, physicians report that procedural times shorten with experience. For operators in training, procedure times, fluoroscopy times, and contrast utilization improved following six months of training for the radial approach.
While the RIFLE STEACS study supports the clinical case for switching from the femoral approach to the radial for angioplasty, more studies will go a long way in proving the continual efficacy of transradial PCI. As radial PCI gains ground in Europe and eventually the United States, physicians may face significant hurdles with implementation that can be mitigated through development of strong training programs and increased operator experience.