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Cardiac valve replacement: An unanswered question
Cardiac Valve Replacement:
ARTHUR
SELZER,
MD,
An Unanswered
Question
FACC
San Francisco, California The May and June 1975 issues of the Journal contained a two part symposium on valve rep1acement.l The papers constituting the symposium were well chosen; the presentation of the subject was adequately balanced. Few will challenge the statement of the guest editor: “Valve replacement has been the most important advance in the last 15 years . . . in valvular heart disease.” Yet one important question remains unanswered and was hardly touched upon in the symposium: Does valve replacement affect the natural history of valvular heart disease in a positive or negative way? This question cannot be answered by pointing to the drama of the totally disabled patient who becomes fully rehabilitated and leads an active life after valve replacement. It can be approached only by a dispassionate comparison of the natural history of various valvular lesions treated medically with the effects of valve replacement as performed at various stages of disease. As the immediate operative risk of valve replacement becomes smaller and as .the late complications become less pronounced, there is a great temptation to replace valves during the early stages of disease, even prophylactically, in asymptomatic patients. More and more, valve replacement is thought of as an inevitable phase in the course of valvular heart disease. In reality, valve replacement represents merely one of three therapeutic options, the other two being less drastic surgical therapy and medical management. In response to the wide prevalence of the overly simplistic view of valve replacement, one can propose and successfully defend a thesis that valve replacement affects the natural history of valvular heart disease negatively; that is, the operation has an overall effect of shortening rather than extending life. A patient about to undergo elective valve replacement gambles: The decision-making party, be it a cardiologist or cardiovascular surgeon, places on a hypothetical scale the estimated risk versus the benefits of the operation. Under “risk” is included not From the Division of Cardiology, Presbyterian Hospital of Pacific Medical Center, San Francisco, Calif. Address for reprints: Arthur Seizer, MD, Division of Cardiology, Pacific Medical Center, P.O. Box 7999, San Francisco, Calif. 94120.
322
February 1976
The American Journal of CARDIOLOGY
only the probability of surviving the operation, but delayed complications, late deaths, failure to improve, and the like. The obvious benefit for which the patient undertakes the gamble is a longer and more comfortable life. How solid are the data upon which this therapeutic equation is weighed, and how carefully are the various options considered in each individual case? Life Expectancy
After Valve Replacement
It is relatively easy to estimate the risk of the operation and its immediate sequelae. However, it is exceedingly difficult to obtain meaningful projections regarding life expectancy after valve replacement. Paton estimates that the 10 year survival rate (exclusive of operative mortality) of patients with the older ball valves and the homograft valves ranges between 60 and 70 percent. These figures have little meaning in view of the frequent changes in prosthetic valves. Valves are being redesigned, new principles applied because of deficiencies of older models. Yet it takes time to discover the potential hazards of artificial valves. It took several years before the enthusiasm for homograft valves was dampened by awareness of the development of late disintegration or stiffening. Cloth-covered ball valves were introduced to reduce thrombotic complications, but in many centers they were abandoned because of complications resulting from tear of the material. It has been stated that the most recent valve models are considered “best,” because not enough time has elapsed to permit recognition of their faults. Other questions related to valve longevity also require answers; for example, how often can one recognize prosthetic valve deterioration in time for safe replacement? How great is the increment of risk of the second, third or fourth reoperation for exchange of prosthetic valves? Thus, it is difficult to project the survival of patients with prosthetic valves for more than 5 to 10 years, and even this estimate can only be rough. In this light, there is only one clinical setting in which valve replacement clearly prolongs life, and that is the middle-aged or elderly patient with aortic stenosis who is symptomatic and whose symptoms are related to the valve obstruction.
Volume 37
EDITORIALS
Natural History of Mitral Stenosis The actuarial curves-admittedly crude indexesindicate that patients with mitral stenosis in New York Heart Association functional class II have about an 80 percent probability of surviving 10 years.3 Ellis and Harken have shown that patients in functional class III have a similar life expectancy after closed mitral valvotomy. But the functional classification of patients with mitral stenosis is difficult because of the many misleading features and prevailing misconceptions. To name a few: Mitral stenosis predominantly affects women and often produces the first disabling symptoms at the menopausal age. It may be difficult to distinguish true cardiac symptoms from the variety of functional complaints related to menopause. We have repeatedly encountered women with mitral stenosis whose careful clinical evaluation appeared to justify placement in functional class III, but whose cardiac catheterization data revealed normal dynamics and trivial mitral stenosis. Yet in many high volume surgical centers only a minority of patients undergo cardiac catheterization; most are referred for surgery on clinical grounds. The onset of cardiac failure in mitral stenosis does not necessarily mean a step down in the natural history: Many patients experience disabling symptoms as a result of reversible complications (atria1 fibrillation, respiratory infections) and return to an asymptomatic state when the precipitating factor is eliminated. Attacks of pulmonary edema in patients with mitral valve disease are ominous clinical emergencies but do not automatically call for early valve replacement. They are often brought on by dietary indiscretion or overexertion and may be easily preventable. The often-repeated statement that “the next attack may be fatal” is fallacious: It is theoretically correct, but the risk of another attack is far less than that of valve replacement. Systemic embolism in otherwise asymptomatic patients with mitral stenosis is not an indication for valve replacement. The operation offers no definite protection from atria1 thrombi, whereas the prosthetic valve may provide an additional source of potential emboli. Our studies5s6 have demonstrated that many patients with mitral stenosis have a nonprogressive stable status. Asymptomatic patients may remain so and live a normal span of life, and the condition of those with mild symptoms may remain unchanged for decades. Thus, the onset of symptoms does not necessarily mean the rapid approach of serious disability. It is evident that the evaluation of patients with mitral stenosis, regardless of their clinical symptoms, requires a careful consideration of all three therapeutic options. Natural History of Mitral Regurgitation The natural history of chronic mitral regurgitation (usually rheumatic in origin) closely resembles that
of mitral stenosis.7 As in the latter, the patient’s symptoms may grow progressively worse or may remain stable for years. Complications and secondary sequelae commonly account for disability, which may be temporary if the causes are reversible or responsive to medical therapy. In rheumatic mitral regurgitation, valve replacement is usually considered the surgical treatment of choice, although in some institutions excellent results have been obtained by a more conservative operation, valvuloplasty.8 Acute forms of mitral regurgitation (idiopathic rupture of chordae tendineae, postendocarditic mitral regurgitation, postinfarctional mitral regurgitation) may produce sudden severe disability. In some cases, valve replacement is life-saving. More often, medical treatment may stabilize the cardiac status to a point where one can carefully evaluate choices-medical versus surgical therapy-as well as determine the feasibility of low risk valvuloplasty.7Tg Suggestions that patients with prolapsing mitral cusps (mid-systolic click, late systolic murmur) undergo valve replacement are ill advised. In these subjects, mitral regurgitation is hemodynamically trivial and, although disabling symptoms such as chest pain and arrhythmias are occasionally present, no evidence has been presented that they are related to mitral valve disease or that mitral valve replacement will alleviate them. Natural History of Aortic Regurgitation Aortic regurgitation presents perhaps the most serious dilemma regarding the timing of valve replacement, which is the only surgical option in this lesion. Patients with aortic regurgitation, even of severe degree, usually remain asymptomatic for years, even decades.lO The lesion is so well tolerated in young subjects that severe cardiac failure is rare before age 40 years. However, when the heart fails, irreversible fibrosis of the myocardium is often present; consequently, results of valve replacement may not lead to the expected improvement. A valid point can be made for replacing valves early, before severe hypertrophy takes place. To do so would mean operating upon asymptomatic young subjects who have a high probability of remaining in functional class I for 2 or 3 decades. Thus, to complete the therapeutic equation, early operation would require results comparable with those of correction of some simple congenital lesions, that is, a 90 to 95 percent probability of surviving 20 years. These results are unattainable with valve replacement, and may in fact never be accomplished. Conclusions Advances in valve replacement have been impressive. However, excessive enthusiasm has swung the pendulum too far from center. The risk-benefit ratio is sometimes derived by comparing an unrealistic expectation of success with the most pessimistic estimate of the natural course. The overemphasis upon valve replacement has led to neglect and declining craftsmanship in performance of less drastic but infi-
February 1976
The American Journal of CARDIOLOGY
Volume 37
323
EDITORIALS
nitely safer operations. The surgical cliche “improvement of quality of life” is often used without regard to the accomplishments of medical therapy. Valve replacement must be considered in its proper perspective, that is, a drastic operation aimed at reduction of disability in the immediate or near future. Its pro-
phylactic use in anticipation of future problems cannot be justified by data now available. Even in symptomatic patients, the decision for valve replacement should be made only after the natural history of the lesion in question is carefully reviewed and the often neglected medical therapy given a fair trial.
References 1. Symposium on current status of valve replacement (Rahimtoola SH, ed). Parts I and II. Am J Cardiol 35710-760, 843-897, 1975 2. Paion BC: Is there a ten-year valve? Adv Cardiol, in press 3. Olesen KH: The natural history of 271 patients with mitral stenosis under medical treatment. Br Heart J 24:349-357, 1962 4. Ellis LB, Harken DE: Closed valvuloplasty for mitral stenosis: a twelve year follow-up study of 1571 patients. N Engl J bled 270:643-650, 1964 5. Dubln AA, March HW, Cohn K, et al: Longitudinal hemodynamic and clinical study of mitral stenosis. Circulation 44:381-389, 1971 6. Seizer A, Cohn K: Natural history of mitral stenosis: a review.
324
February 1976
The American Journal of CARDIOLOGY
Circulation 45:878-890, 1972 7. Setzer A, Katayama F: Mitral regurgitation: clinical patterns, pathophysiology, and natural history. Medicine 51:337-366. 1972 8. Stevenson JG, Kawaborl I, Morgan BCM, et al: Rheumatic mitral regurgitation: the case for annuloplasty in the pediatric group. Circulation 51, 52:Suppl l:l-149-l-151, 1975 9. Seizer A, Kelly JJ, Kerth WJ, et al: Immediate and long-range results of valvuloplasty for mitral regurgitation due to ruptured chordae tendineae. Circulation 45. 46:Suppl 1:1-152-l-156, 1972. 10. Goldschlager N, Pfeifer J, Cohn K, et al: The natural history of aortic regurgitation. A clinical and hemodynamic study. Am J Med 54~577-588, 1973
Volume 37
ARTHUR
SELZER,
MD,
An Unanswered
Question
FACC
San Francisco, California The May and June 1975 issues of the Journal contained a two part symposium on valve rep1acement.l The papers constituting the symposium were well chosen; the presentation of the subject was adequately balanced. Few will challenge the statement of the guest editor: “Valve replacement has been the most important advance in the last 15 years . . . in valvular heart disease.” Yet one important question remains unanswered and was hardly touched upon in the symposium: Does valve replacement affect the natural history of valvular heart disease in a positive or negative way? This question cannot be answered by pointing to the drama of the totally disabled patient who becomes fully rehabilitated and leads an active life after valve replacement. It can be approached only by a dispassionate comparison of the natural history of various valvular lesions treated medically with the effects of valve replacement as performed at various stages of disease. As the immediate operative risk of valve replacement becomes smaller and as .the late complications become less pronounced, there is a great temptation to replace valves during the early stages of disease, even prophylactically, in asymptomatic patients. More and more, valve replacement is thought of as an inevitable phase in the course of valvular heart disease. In reality, valve replacement represents merely one of three therapeutic options, the other two being less drastic surgical therapy and medical management. In response to the wide prevalence of the overly simplistic view of valve replacement, one can propose and successfully defend a thesis that valve replacement affects the natural history of valvular heart disease negatively; that is, the operation has an overall effect of shortening rather than extending life. A patient about to undergo elective valve replacement gambles: The decision-making party, be it a cardiologist or cardiovascular surgeon, places on a hypothetical scale the estimated risk versus the benefits of the operation. Under “risk” is included not From the Division of Cardiology, Presbyterian Hospital of Pacific Medical Center, San Francisco, Calif. Address for reprints: Arthur Seizer, MD, Division of Cardiology, Pacific Medical Center, P.O. Box 7999, San Francisco, Calif. 94120.
322
February 1976
The American Journal of CARDIOLOGY
only the probability of surviving the operation, but delayed complications, late deaths, failure to improve, and the like. The obvious benefit for which the patient undertakes the gamble is a longer and more comfortable life. How solid are the data upon which this therapeutic equation is weighed, and how carefully are the various options considered in each individual case? Life Expectancy
After Valve Replacement
It is relatively easy to estimate the risk of the operation and its immediate sequelae. However, it is exceedingly difficult to obtain meaningful projections regarding life expectancy after valve replacement. Paton estimates that the 10 year survival rate (exclusive of operative mortality) of patients with the older ball valves and the homograft valves ranges between 60 and 70 percent. These figures have little meaning in view of the frequent changes in prosthetic valves. Valves are being redesigned, new principles applied because of deficiencies of older models. Yet it takes time to discover the potential hazards of artificial valves. It took several years before the enthusiasm for homograft valves was dampened by awareness of the development of late disintegration or stiffening. Cloth-covered ball valves were introduced to reduce thrombotic complications, but in many centers they were abandoned because of complications resulting from tear of the material. It has been stated that the most recent valve models are considered “best,” because not enough time has elapsed to permit recognition of their faults. Other questions related to valve longevity also require answers; for example, how often can one recognize prosthetic valve deterioration in time for safe replacement? How great is the increment of risk of the second, third or fourth reoperation for exchange of prosthetic valves? Thus, it is difficult to project the survival of patients with prosthetic valves for more than 5 to 10 years, and even this estimate can only be rough. In this light, there is only one clinical setting in which valve replacement clearly prolongs life, and that is the middle-aged or elderly patient with aortic stenosis who is symptomatic and whose symptoms are related to the valve obstruction.
Volume 37
EDITORIALS
Natural History of Mitral Stenosis The actuarial curves-admittedly crude indexesindicate that patients with mitral stenosis in New York Heart Association functional class II have about an 80 percent probability of surviving 10 years.3 Ellis and Harken have shown that patients in functional class III have a similar life expectancy after closed mitral valvotomy. But the functional classification of patients with mitral stenosis is difficult because of the many misleading features and prevailing misconceptions. To name a few: Mitral stenosis predominantly affects women and often produces the first disabling symptoms at the menopausal age. It may be difficult to distinguish true cardiac symptoms from the variety of functional complaints related to menopause. We have repeatedly encountered women with mitral stenosis whose careful clinical evaluation appeared to justify placement in functional class III, but whose cardiac catheterization data revealed normal dynamics and trivial mitral stenosis. Yet in many high volume surgical centers only a minority of patients undergo cardiac catheterization; most are referred for surgery on clinical grounds. The onset of cardiac failure in mitral stenosis does not necessarily mean a step down in the natural history: Many patients experience disabling symptoms as a result of reversible complications (atria1 fibrillation, respiratory infections) and return to an asymptomatic state when the precipitating factor is eliminated. Attacks of pulmonary edema in patients with mitral valve disease are ominous clinical emergencies but do not automatically call for early valve replacement. They are often brought on by dietary indiscretion or overexertion and may be easily preventable. The often-repeated statement that “the next attack may be fatal” is fallacious: It is theoretically correct, but the risk of another attack is far less than that of valve replacement. Systemic embolism in otherwise asymptomatic patients with mitral stenosis is not an indication for valve replacement. The operation offers no definite protection from atria1 thrombi, whereas the prosthetic valve may provide an additional source of potential emboli. Our studies5s6 have demonstrated that many patients with mitral stenosis have a nonprogressive stable status. Asymptomatic patients may remain so and live a normal span of life, and the condition of those with mild symptoms may remain unchanged for decades. Thus, the onset of symptoms does not necessarily mean the rapid approach of serious disability. It is evident that the evaluation of patients with mitral stenosis, regardless of their clinical symptoms, requires a careful consideration of all three therapeutic options. Natural History of Mitral Regurgitation The natural history of chronic mitral regurgitation (usually rheumatic in origin) closely resembles that
of mitral stenosis.7 As in the latter, the patient’s symptoms may grow progressively worse or may remain stable for years. Complications and secondary sequelae commonly account for disability, which may be temporary if the causes are reversible or responsive to medical therapy. In rheumatic mitral regurgitation, valve replacement is usually considered the surgical treatment of choice, although in some institutions excellent results have been obtained by a more conservative operation, valvuloplasty.8 Acute forms of mitral regurgitation (idiopathic rupture of chordae tendineae, postendocarditic mitral regurgitation, postinfarctional mitral regurgitation) may produce sudden severe disability. In some cases, valve replacement is life-saving. More often, medical treatment may stabilize the cardiac status to a point where one can carefully evaluate choices-medical versus surgical therapy-as well as determine the feasibility of low risk valvuloplasty.7Tg Suggestions that patients with prolapsing mitral cusps (mid-systolic click, late systolic murmur) undergo valve replacement are ill advised. In these subjects, mitral regurgitation is hemodynamically trivial and, although disabling symptoms such as chest pain and arrhythmias are occasionally present, no evidence has been presented that they are related to mitral valve disease or that mitral valve replacement will alleviate them. Natural History of Aortic Regurgitation Aortic regurgitation presents perhaps the most serious dilemma regarding the timing of valve replacement, which is the only surgical option in this lesion. Patients with aortic regurgitation, even of severe degree, usually remain asymptomatic for years, even decades.lO The lesion is so well tolerated in young subjects that severe cardiac failure is rare before age 40 years. However, when the heart fails, irreversible fibrosis of the myocardium is often present; consequently, results of valve replacement may not lead to the expected improvement. A valid point can be made for replacing valves early, before severe hypertrophy takes place. To do so would mean operating upon asymptomatic young subjects who have a high probability of remaining in functional class I for 2 or 3 decades. Thus, to complete the therapeutic equation, early operation would require results comparable with those of correction of some simple congenital lesions, that is, a 90 to 95 percent probability of surviving 20 years. These results are unattainable with valve replacement, and may in fact never be accomplished. Conclusions Advances in valve replacement have been impressive. However, excessive enthusiasm has swung the pendulum too far from center. The risk-benefit ratio is sometimes derived by comparing an unrealistic expectation of success with the most pessimistic estimate of the natural course. The overemphasis upon valve replacement has led to neglect and declining craftsmanship in performance of less drastic but infi-
February 1976
The American Journal of CARDIOLOGY
Volume 37
323
EDITORIALS
nitely safer operations. The surgical cliche “improvement of quality of life” is often used without regard to the accomplishments of medical therapy. Valve replacement must be considered in its proper perspective, that is, a drastic operation aimed at reduction of disability in the immediate or near future. Its pro-
phylactic use in anticipation of future problems cannot be justified by data now available. Even in symptomatic patients, the decision for valve replacement should be made only after the natural history of the lesion in question is carefully reviewed and the often neglected medical therapy given a fair trial.
References 1. Symposium on current status of valve replacement (Rahimtoola SH, ed). Parts I and II. Am J Cardiol 35710-760, 843-897, 1975 2. Paion BC: Is there a ten-year valve? Adv Cardiol, in press 3. Olesen KH: The natural history of 271 patients with mitral stenosis under medical treatment. Br Heart J 24:349-357, 1962 4. Ellis LB, Harken DE: Closed valvuloplasty for mitral stenosis: a twelve year follow-up study of 1571 patients. N Engl J bled 270:643-650, 1964 5. Dubln AA, March HW, Cohn K, et al: Longitudinal hemodynamic and clinical study of mitral stenosis. Circulation 44:381-389, 1971 6. Seizer A, Cohn K: Natural history of mitral stenosis: a review.
324
February 1976
The American Journal of CARDIOLOGY
Circulation 45:878-890, 1972 7. Setzer A, Katayama F: Mitral regurgitation: clinical patterns, pathophysiology, and natural history. Medicine 51:337-366. 1972 8. Stevenson JG, Kawaborl I, Morgan BCM, et al: Rheumatic mitral regurgitation: the case for annuloplasty in the pediatric group. Circulation 51, 52:Suppl l:l-149-l-151, 1975 9. Seizer A, Kelly JJ, Kerth WJ, et al: Immediate and long-range results of valvuloplasty for mitral regurgitation due to ruptured chordae tendineae. Circulation 45. 46:Suppl 1:1-152-l-156, 1972. 10. Goldschlager N, Pfeifer J, Cohn K, et al: The natural history of aortic regurgitation. A clinical and hemodynamic study. Am J Med 54~577-588, 1973
Volume 37