Is it appropriate to compare the results from two clinical trials with one drug in common?

factor to be considered when determining patient suitability for transcatheter implantation. Variables such as calcium quantity and distribution, the width of the sinuses of Valsalva, outflow tract diameter or computed tomography-measured annulus diameter (maximum annulus diameter was 23.9 mm) must also be analyzed. Since percutaneous implantation techniques began to be used for aortic valves, previous valvuloplasty has been considered obligatory to facilitate the progress and optimal expansion of the prosthesis. 5 Although several cases of direct valve-in-valve implantation of Edwards-SAPIEN prostheses without previous valvuloplasty have been described, we are not aware of any cases of direct native valve implantation in patients with aortic stenosis. Grube et al. 6 recently described CoreValve W self-expanding prosthesis (Medtronic; Minneapolis, Minnesota, United States) implantation without valvuloplasty, and concluded that the technique was safe and feasible. Balloon valvuloplasty can cause severe aortic regurgitation and hemo-dynamic instability in some patients and could favor the migration of calcium particles to the cerebral circulation. Direct implantation without valvuloplasty would avoid these complications in some patients with favorable anatomy (low levels of calcification, homogeneous distribution and symmetrical native valve opening). 6 Moreover, given native valve characteristics, prosthesis placement and expansion might be the same or better than when using the conventional technique. In our patient these anatomic criteria were favorable, with moderate valve calcification. The difficulties that might be encountered during implantation and their possible solutions are as follows: Advancing the prosthesis through the native valve may not be feasible. Should this occur, it is essential to avoid forcing progress and perform valvuloplasty via the contralateral femoral artery delivery catheter. Correctly positioning the prosthesis may be difficult if valve calcification is minimal. Hence, we consider the use of echocardiography during implantation to be essential. Given that the Edwards-SAPIEN XT prosthesis expands by volume, expansion may be insufficient. We believe that slow, progressive balloon inflation, maintained for !5 s during implantation ensures adequate expansion. One further advantage—although it was not considered essential when choosing the technique described—is that if this technique is shown to be appropriate for specific patients, kits could be prepared for this patient group, which would cut the cost of packs with no balloon. This is the first case of transfemoral implantation of an Edwards-SAPIEN XT aortic prosthesis without previous valvulo-plasty. We believe it is technically possible and could be safer than traditional implantation in suitable patients (those with low levels of valve calcification, homogeneous calcium distribution …