Invited commentary

Abstract

Murday et al have documented the only prospective randomized trial comparing the St. Jude Medical and the Starr-Edwards aortic and mitral prostheses in the English literature. The investigators are congratulated for contributing to evidence based management. This study has been long overdue, for the Starr-Edwards prosthesis has been used for 40 years and the St. Jude Medical prosthesis for 25 years. The clinical performance of these two prostheses has been designated the “gold standard” in their respective eras. The authors, although, have not provided an hypothesis for their study, nor a power calculation to prove their hypothesis. It is assumed the study was conducted only to evaluate the comparative clinical performance of the two prostheses. The two prostheses have enjoyed extended durability with only sporadic reports of structural failure, particularly with the poppet of the Starr-Edwards prosthesis. There have been three models of the Starr-Edwards inclusive of the poppet ball material cloth-covered prosthesis, and the track prosthesis. The investigators are documenting similar performances between the two prostheses with regard to survival, and valve-related complications of thromboembolism and anti-thrombotic hemorrhage. The study has confirmed that the degrees of ventricular dysfunction, as well as age, are the predominant predictors of survival. These results do not mean that the two prostheses have similar clinical performance. The investigators have documented only overall thromboembolism with no differentiation for major, reversible ischemic neurological deficits (RIND) and minor events. There may be a differentiation between the two prostheses. The major issue with the study is related to the anticoagulation management. The target INR for the study was 3.0—4.0 for both aortic and mitral prostheses with both valve types. The anticoagulant level is reflected in five years freedom from hemorrhage of approximately 80% for both types and positions. The current recommended INR targets for the St Jude Medical prostheses are 2.0— 3.0 for aortic prostheses and 2.5—3.5 for mitral prostheses. There has always been a general opinion that the Starr-Edwards prosthesis in both positions requires higher INR levels to prevent thromboembolic events. The target INR may be necessary of the Starr-Edwards, but not for the St. Jude Medical prosthesis. This translates into a higher haemorrhage rate, with an INR target higher than necessary to minimize thromboembolism events. This means that the two prostheses may not be performing at the same level. The investigators have not identified the pannus complication reported with the Starr-Edwards prosthesis, especially in the subaortic position, and possibly with subvalvular apparatus preserving mitral valve replacement. The randomized trial has provided evidence of excellent performance, safety, and durability of both prostheses. The changing patterns of practice and potential changing standards of care are the cause of limitations of randomized trials. Irrespective of limitations, randomized trials are the superior method to develop evidence-based standards of care. Congratulations to Murday and colleagues for their determination to conduct this long overdue randomized trial.