In what has been reported as the most anticipated session of the conference, Dr. Martyn Thomas-a lead physician in the world of transcatheter aortic valve implantation (TAVI)-presented updated data from the European SOURCE registry at EuroPCR this week. This presentation, focused primarily on one-year data for patients enrolled in cohort 1 of the SOURCE registry (those who underwent transapical delivery), showed that survival rates for the two delivery methods are showing closer results than seen in previous studies.
Specifically, patients undergoing transapical delivery now show 12-month survival rates of 72% in comparison to transfemoral patients that have 12-month survival rates of 81.1%. This is greatly improved over previous comparisons that used the early studies REVIVE, REVIVAL, TRAVERCE, and PARTNER EU in which transapical performed at an abysmal 58% versus transfemoral at 74.9%.
These new results add additional fuel to the transcatheter valve fire and for the most part are in favor of TAVI supporters. With everyone in the field anxiously awaiting the initial results from the US PARTNER trial--likely at TCT 2010 in October in Washington, DC--these data further promote these therapies as a means to treat not only very sick patients, but perhaps those at a lower risk. Patients undergoing these procedures thus far have been those too sick for surgery and otherwise thought of as ineligible. Furthermore, those receiving the device through transapical implantation traditionally represent the most severe patients receiving TAVI due to increased comorbidities and/or poor vascular access. These data show that even the sickest patients are performing in a similar follow up to those in the transfemoral arm; easing (even if only slightly) the fear with the procedures.
Moreover, even more telling was Dr. Thomas's analyses that stratified 12-month survival rates for both transfemoral and transapical patients according to baseline EuroSCORE (one of the current determinants for patient eligibility). This analysis shows that in patients at the lowest surgical risk (those with a EuroSCORE less than 20) one year survival was very similar between the two groups (78.4% for TA, 80.9% for TF). These updated data are encouraging such that they are contributing to a push for even more comparisons and discussions surrounding patient risk. Most notably has been the vivid debate not just at EuroPCR, but all the clinical conferences this year, around the ability to measure a patient's risk and need for this procedure. It has repeatedly been said that EuroSCOREs and STS scores are not sufficient to judge a patient's risk when undergoing this procedure. These debates have called for a new scoring methodology whereas physicians and the societies develop a "TAVI risk score" that would be more appropriate for these patients and procedures. Further, as the discussion around risk expands, so does the debate about using this procedure for lower risk patients. Only time, (and more clinical trials) will tell on this debate; hopefully, one of which will be the SOURCE registry's newly announced cohort 2 study which has begun enrolling low risk patients undergoing the TAVI procedures.