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We appreciate the interest that Collison and colleagues [1Collison S. Mishra Y. Meherwal Z.S. Aortic valve replacement with 17-mm prosthesis: emerging evidence of its efficacy (letter).Ann Thorac Surg. 2008; 85: 692-693Abstract Full Text Full Text PDF PubMed Scopus (1) Google Scholar] have shown in our article, which describes our observational findings of the efficacy of aortic valve replacement with a 17-mm mechanical prosthesis [2Takaseya T. Kawara T. Tokunaga S. et al.Aortic valve replacement with 17-mm St Jude Medical Prostheses for a small aortic root in elderly patients.Ann Thorac Surg. 2007; 83: 2050-2053Abstract Full Text Full Text PDF PubMed Scopus (24) Google Scholar]. We appreciate their careful critique and we respond to their comment as follows: The SJM Regent Valve (St. Jude Medical, St. Paul, MN) was developed as a new mechanical valve by improving the conventional SJM Valve (St. Jude Medical). In our study, we undertook aortic valve replacement for elderly patients with a 17-mm SJM Regent Valve. Our echocardiography data demonstrated that the mean effective orifice area index (EOAI) was 0.87. Kratz and associates [3Kratz J.M. Sade R.M. Crawford Jr, F.A. Crumbley III, A.J. Stroud M.R. The risk of small St Jude aortic valve prosthesis.Ann Thorac Surg. 1994; 57: 1114-1119Abstract Full Text PDF PubMed Scopus (86) Google Scholar] suggested that a body surface area (BSA) greater than 1.7 m2 is a predictor of late death in patients who received small-sized SJM valves. Our study targeted small elderly women with an average BSA of 1.33, but if we were to instead target those with an average BSA of 1.7 or higher, then the EOAI would have been 0.68 or lower. On the other hand, Swant and associates [4Swant D. Singh A.K. Feng W.C. Bert A.A. Rotenberg F. Nineteen-millimeter aortic St Jude Medical heart valve prosthesis: up to sixteen years’ follow-up.Ann Thorac Surg. 1997; 63: 964-970Abstract Full Text Full Text PDF PubMed Scopus (39) Google Scholar] did not find a BSA greater than 1.7 m2 to be a risk factor for long-term survival in patients who received 19-mm St. Jude valves. Moreover, our elderly patients generally have a more limited peak exercise capacity than that of younger individuals. Therefore, we advocate that patient-prosthesis mismatch does not occur and a 17-mm SJM Regent Valve prosthesis would be the optimal choice in elderly patients with a BSA greater than 1.7 cm2. Finally, it is most important to maintain good anticoagulation in elderly patients. After our manuscript was accepted, 1 of our patients was referred back to our hospital because of progressive anemia. In this case, there was a marked elevation in the prothrombin time international normalized ratio (PT-INR), with subsequent gastrointestinal bleeding. We recommend monthly monitoring of coagulation measurements for all elderly patients receiving warfarin. The INR of elderly patients should be kept between 1.8 and 2.5 with an appropriate adjustment of the warfarin dose. Aortic Valve Replacement With 17-mm Prosthesis: Emerging Evidence of Its EfficacyThe Annals of Thoracic SurgeryVol. 85Issue 2PreviewIn a recent article, Takaseya and colleagues [1] reported 11 elderly women (mean body surface area [BSA], 1.33 ± 0.13 cm/m2) who received a 17-mm prosthesis at the time of aortic valve replacement (AVR) with good results. We believe that the analysis of this study would be enhanced by emphasizing the following: Full-Text PDF