Transcatheter Aortic Valve Implantation

Since the first reported clinical implantation of a transcatheter valve in 2002,1 the rapidity of assimilation into the clinical arena of this novel technology has been astonishing. Transcatheter aortic valve implantation, either retrograde through a transfemoral approach or antegrade through a transapical approach, has become a clinical reality in the treatment critical aortic stenosis in high-risk patients. Commercialization of both self-expanding and balloon expandable platforms in Europe, as an alternative to conventional aortic valve replacement, has led to the implantation of more than 2000 such valves worldwide. Early clinical results are positive and have generated intense interest in this technology, along with intense scrutiny. Despite the rapid advances, procedural mortality remains high in comparison with some traditional populations having aortic valve replacement. It cannot be over emphasized, however, that the patients undergoing these procedures are unlike those previously described in the surgical literature in terms of comorbidities, estimated operative mortality, and degree of frailty or debility. The accompanying review article provides an excellent overview of the evolution of transcatheter valve therapy, a synopsis of the current commercially available devices, and highlights potential candidates for this new therapy. The authors also cover the relative advantages and disadvantages of both approaches to the aortic valve: transfemoral and transapical. Furthermore, they expound on their extensive experience with transcatheter intervention and the clinical results seen at their institution and worldwide. Like many other authors, they report increased operative mortality and reduced long-term survival in their transapical population as compared with transfemoral patients. These types of results, that ineluctably lead observers to question the transapical technique, need to be placed in context and candidly discussed to prevent misconceptions regarding the approach. Many observers have raised the question of worse early and long-term outcomes with the transapical as compared with the transfemoral approach. Unfortunately, relying only on reported outcomes without appreciating the context within which these procedures are being performed does a disservice to the transapical approach. The authors report operative mortality for both transapical and transfemoral procedures using the Edwards SAPIEN valve. They note an operative mortality of 7.9% in their recent transfemoral patients compared with 13.5% in those having a transapical implant. Mentioned, but not emphasized however, is the fact that they use a “transfemoral first” approach to transcatheter therapy. In other words, only the absolute worst patients are offered transapical implantation, ie, those patients refused both conventional surgery and tranfemoral implantation. These patients have a significantly higher incidence of severe occlusive peripheral vascular disease (an identified risk factor for poor outcomes with valvular heart surgery), higher Logistic EuroSCORES scores, and a greater incidence of previous coronary artery disease. In fact, in a recent study presented at the 45 Annual Meeting of The Society of Thoracic Surgeons in January 2009, logistic regression analysis demon-