Dr. Adams cautioned that it will be important to duplicate the rigorous risk assessment process of clinical trials at individual centers and urged clinical estimation of surgical mortality to take into account all incremental risks associated with a patient, as is being done in the CoreValve pivotal trial through the use of an incremental scoring system. For example, a 70-year-old patient with New York Heart Association Class III disease, a history of peripheral vascular disease, pulmonary hypertension, Child’s Class A liver dysfunction and one prior open heart surgery may have a STS mortality risk score of around 8%, but the total incremental mortality risk reaches close to 20% after accounting for the pulmonary hypertension and liver dysfunction, neither of which is part of the STS scoring system at this time.
When audience members asked about the learning curve for TAVI, Dr. Herrmann said it takes a minimum of 10 to 30 cases to even know what you’re doing, and that this number differs as to whether patients are treated with a transfemoral or transapical approach. He noted that Edwards Lifesciences and the U.S. Food and Drug Administration are setting up an intensive training program with simulations, an expert review of cases, and a proctoring system. Only four sites will be designated to train American physicians in the procedure.
Still, the challenge for Edwards and other companies that will follow will be enormous in terms of launching this technology outside the clinical trial setting, Dr. Adams said.
"You cannot overestimate the amount of company support you’re going to need to do these things safely," he said. "This is not a new widget you can pick up and get comfortable with in one or two cases like a new repair ring or new stent ... It’s a whole new process."
Dr. Herrmann reported financial relationships with Abbott, Edwards Lifesciences, Medtronic, St. Jude Medical, and Micro Interventional Devices. Dr. Adams reported royalties as an inventor for Edwards and Medtronic and serving as an uncompensated coprincipal investigator for the Medtronic CoreValve U.S. trial.