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Cardiac Valve Replacement
194 The Annals of Thoracic Surgery Vol 29 No 2 February 1980
the outcome is attributed. Editors and reviewers are fairly good judges of what clinical conditions and what surgical procedures would seem to be reasonable subjects for such trials. In such areas, reports of uncontrolled studies would be viewed more critically, and their authors might be required to provide additional evidence for claims of validity. If, in fact, ideal conditions always prevailed-including the establishment of prospective criteria for inclusion in a trial, with all patients meeting the criteria and with uniformity of classification of clinical groups, accuracy of observation and of data collection, and scrupulous honesty of reporting-there might well be fewer operative procedures being performed after many decades about which there still remains considerable doubt. Prospective randomized controlled trials provide a reasonable alternative (though not a perfect one) for avoiding some of the difficulties of the past. Titnothy Takaro, M . D . Surgical Services Veteraris Adniiti istratio t i Askeville, N C 28805 Wilbert Arotiow, M . D . Utiiuersity of California Henry Blackburti, M . D . University of Mititiesota David P . Boyd, M . D . Lahey Clinic C . Richard Conti, M . D . University of Florida Henry 0 . Mclritosli, M . D . Watsori Clitiic Thomas A . Preston, M . D . U.S. Public Health Seruice (Seattle, W A )
Arthur Selzer, M . D . University of Califorriia David H . Spodick, M . D . University of Massachusetts Medical school
Cardiac Valve Replacement To the Editor: A cardiac surgeon reviewing current literature to determine which prosthetic valve to use would reach conclusions that differ from those of Dr. Roberts in his editorial ”Factors Determining Outcome of Cardiac Valve Replacement” (Ann Thorac Surg 27:101, 1979).Actuarial survival at five years following aortic valve replacement is 74 to 80% whether the valve used is a Smeloff-Cutter, Starr-Edwards (bare-strut or cloth-covered), Bjork-Shiley, or Hancock porcine xenograft. Also, five-year survival after mitral valve replacement is similar for these valves. Overall long-term survival figures are not significantly altered in series in which valves with known lethal complications, such as valve thrombosis or poppet escape, were employed. With the four valves mentioned, at least, current analysis does not support the statement that “the most important factor determining the long-term outcome of valve replacement is the type of substitute valve inserted.” Rather, the factors of age, preoperative heart size, and functional class recur as the dominant predictors of long-term success or failure. Valve selection does need to be individualized and surgeons must be aware of the hemodynamic, thromboembolic, and durability characteristics of the prosthesis they choose. None of the current prostheses are perfect, but those who think that simple selection of a valve will change unsatisfactory results are referred to a consecutive series of 100 patients who underwent aortic valve replacement fifteen years ago without mortality. The prosthesis used is not considered ideal, but their longterm survival is consistent with the best results using other prostheses.
Donald J. Magilligan, Jr, M . D . Division of Cardiac and Thoracic Surgery Hen y Ford Hospital 2799 W Grand Blvd Detroit, M I 48202
the outcome is attributed. Editors and reviewers are fairly good judges of what clinical conditions and what surgical procedures would seem to be reasonable subjects for such trials. In such areas, reports of uncontrolled studies would be viewed more critically, and their authors might be required to provide additional evidence for claims of validity. If, in fact, ideal conditions always prevailed-including the establishment of prospective criteria for inclusion in a trial, with all patients meeting the criteria and with uniformity of classification of clinical groups, accuracy of observation and of data collection, and scrupulous honesty of reporting-there might well be fewer operative procedures being performed after many decades about which there still remains considerable doubt. Prospective randomized controlled trials provide a reasonable alternative (though not a perfect one) for avoiding some of the difficulties of the past. Titnothy Takaro, M . D . Surgical Services Veteraris Adniiti istratio t i Askeville, N C 28805 Wilbert Arotiow, M . D . Utiiuersity of California Henry Blackburti, M . D . University of Mititiesota David P . Boyd, M . D . Lahey Clinic C . Richard Conti, M . D . University of Florida Henry 0 . Mclritosli, M . D . Watsori Clitiic Thomas A . Preston, M . D . U.S. Public Health Seruice (Seattle, W A )
Arthur Selzer, M . D . University of Califorriia David H . Spodick, M . D . University of Massachusetts Medical school
Cardiac Valve Replacement To the Editor: A cardiac surgeon reviewing current literature to determine which prosthetic valve to use would reach conclusions that differ from those of Dr. Roberts in his editorial ”Factors Determining Outcome of Cardiac Valve Replacement” (Ann Thorac Surg 27:101, 1979).Actuarial survival at five years following aortic valve replacement is 74 to 80% whether the valve used is a Smeloff-Cutter, Starr-Edwards (bare-strut or cloth-covered), Bjork-Shiley, or Hancock porcine xenograft. Also, five-year survival after mitral valve replacement is similar for these valves. Overall long-term survival figures are not significantly altered in series in which valves with known lethal complications, such as valve thrombosis or poppet escape, were employed. With the four valves mentioned, at least, current analysis does not support the statement that “the most important factor determining the long-term outcome of valve replacement is the type of substitute valve inserted.” Rather, the factors of age, preoperative heart size, and functional class recur as the dominant predictors of long-term success or failure. Valve selection does need to be individualized and surgeons must be aware of the hemodynamic, thromboembolic, and durability characteristics of the prosthesis they choose. None of the current prostheses are perfect, but those who think that simple selection of a valve will change unsatisfactory results are referred to a consecutive series of 100 patients who underwent aortic valve replacement fifteen years ago without mortality. The prosthesis used is not considered ideal, but their longterm survival is consistent with the best results using other prostheses.
Donald J. Magilligan, Jr, M . D . Division of Cardiac and Thoracic Surgery Hen y Ford Hospital 2799 W Grand Blvd Detroit, M I 48202