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Ann Thorac Surg 1996;61:1691-1692
© 1996 The Society of Thoracic Surgeons
DR FREDERICK L. GROVER (Denver, CO): I was curious that you found no relationship between aortic valve gradient and interval between the first operation and the second operation. Perhaps Dr Fiore might want to comment on this. I judge that the St. Louis group believed that you could somewhat predict the interval?
DR ANDREW C. FIORE (St. Louis, MO): In this regard, our data agree with those of Dr Hoff and associates. Linear regression analysis could not demonstrate any relationship between the degree of stenosis and the interval to aortic valve replacement.
DR RONALD C. ELKINS (Oklahoma City, OK): I congratulate Hoff and associates on a very good presentation. I would like to ask them to go back and seriously look at their data, and consider those patients who had: (1) rheumatic heart disease (I assume the patient who required a mitral valve replacement subsequently did indeed have rheumatic heart disease); (2) a congenital lesion, ie, a bicuspid aortic valve; and (3) sclerotic aortic valve stenosis. By grouping, they may find a difference in the rates of progression among the groups. This might provide information that would allow us to manage these patients better. For example, a patient who has aortic valve disease and a bicuspid valve is likely to have marked insufficiency associated with the stenosis, versus a patient with a three-leaflet valve that is primarily sclerotic, who is unlikely ever to experience aortic insufficiency as part of his lesion.
DR HOFF: I thank all the discussants for their comments.
Doctor Fiore and Dr Grover both bring up the point of the interval between myocardial revascularization and subsequent aortic valve replacement. We analyzed the mean peak gradient at the time of the initial procedure as well as the subsequent procedure, and the interval to aortic valve replacement. We did not have enough data for a better means of analyzing this statistically, as Dr Fiore has just mentioned. These data with regard to valve gradient are so highly dependent on other factors, such as cardiac output, that they provide little statistical importance, but they do give you a feel for the variability among these patients.
It is interesting that although the numbers are small, they are relatively bimodal. There is a small group of patients who have little if any aortic stenosis at the time of their initial myocardial revascularization. Clinically significant aortic stenosis develops at varying rates, in some as quickly as 4 years after their initial myocardial revascularization. Other cases progress for as long as 17 years before the need for aortic valve replacement.
There is a second group of patients, whom I think we would more accurately put in the group of mild to moderate aortic stenosis at the initial myocardial revascularization. In these patients, too, there is substantial variability with regard to the interval between the initial coronary bypass and their subsequent aortic valve replacement. This may be as short as 3 or 4 years after the initial procedure, but often extends for as long as 10 to 12 years, with no apparent relationship between how severe their initial stenosis is and how long it will take before they become symptomatic or require operation.
With regard to Dr Elkins' comments, I think that there certainly is evidence in the literature that there may be small subgroups of patients within this population who may benefit from consideration of an aortic valve procedure at the initial myocardial revascularization. Patients with rheumatic heart disease or a bicuspid aortic valve may be two small subsets who could potentially benefit from consideration of an aortic valve procedure at the time of their revascularization, whether it be aortic valve replacement or some type of aortic valvuloplasty.
In conclusion, I think that this discussion of how to deal with the patient with mild to moderate aortic valve disease and whether to replace the aortic valve at the time of coronary bypass is a difficult one, one that is multifactorial and about which we obviously have not come to a consensus. There are many factors to be considered. On one hand, replacing the valve early may be important because of the higher operative mortality rate at the time of reoperation; it may reduce the risk of sudden death in the asymptomatic phase of aortic stenosis or reduce valve-related complications in patients who perhaps are already taking warfarin for intermittent or chronic atrial fibrillation. On the other hand, there are those who would suggest-and I think our group is among them-that aortic valve replacement, although challenging after a previous myocardial revascularization, is a relatively safe procedure and that there certainly is an incidence of valve-related morbidity and mortality that goes along with having this prosthesis for several years. Furthermore, in the asymptomatic phase of aortic stenosis, morbidity and mortality rates are relatively low, so our current practice is to observe these patients closely after their coronary bypass and to perform aortic valve replacement once they become symptomatic.
Related Article
Ann. Thorac. Surg. 1996 61: 1689-1691.
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