Correspondence
Predictors of Outcome in Asymptomatic Aortic Stenosis
N Engl J Med 2001; 344:227-229January 18, 2001
- Article
To the Editor:
In their prospective study of patients with asymptomatic aortic stenosis, Rosenhek et al. (Aug. 31 issue)1 note that the rate of progression of aortic-jet velocity was significantly higher in patients who underwent aortic-valve replacement or died from cardiac causes. Others have shown similar results.2
However, the rate of change in the aortic-jet velocity might in itself influence the decision to perform surgery. Physicians may refer patients for valve replacement after observing an increase in aortic-jet velocity because they believe that the increase indicates a worsening prognosis. This approach is supported by the guidelines of the American Heart Association, which include severe asymptomatic aortic stenosis as a class IIb indication for valve replacement.3 The British Cardiac Society recommends surgery both in the presence of symptoms and if the gradient is particularly high.4 In the prospective study by Pellikka et al.,5 18 of 143 asymptomatic patients (13 percent) underwent valve replacement because it was thought that the severity of stenosis itself warranted intervention.
Alternatively, physicians might be more inclined to interpret mild, nonspecific breathlessness as overt exercise limitation if the aortic-jet velocity is high. We recently reviewed a series of patients with severe aortic stenosis and mild breathlessness (with a score of 2 on the Specific Activity Scale). In those referred for aortic-valve replacement, the average peak velocity was 4.4 m per second. However, despite similar symptoms, other patients were being treated conservatively, and in these the average peak velocity was only 3.9 m per second.
It would therefore be an advantage to have an objective measure of functional capacity. Treadmill exercise testing has been shown to be safe in patients without overt severe symptoms. A decline in exercise time may be a more useful predictor of the onset of symptoms than an increase in peak aortic-jet velocity alone, and we suggest that this possibility should be investigated prospectively.
5 ReferencesPaul Das, M.R.C.P.
John Chambers, M.D.
Guy's and St. Thomas' Hospitals, London SE1 7EH, United Kingdom1
Rosenhek R ,Binder T ,Porenta G , et al. Predictors of outcome in severe, asymptomatic aortic stenosis. N Engl J Med 2000;343:611-617
Full Text | Web of Science | Medline2
Otto CM ,Burwash IG ,Legget ME , et al. Prospective study of asymptomatic valvular aortic stenosis: clinical, echocardiographic, and exercise predictors of outcome. Circulation 1997;95:2262-2270
Web of Science | Medline3
Bonow R ,Carabello B ,de Leon AC Jr , et al. Guidelines for the management of patients with valvular disease: executive summary. Circulation 1998;98:1949-1984
Web of Science | Medline4
Prendergast BD ,Banning AP ,Hall RJC . Valvular heart disease: recommendations for investigation and management. J R Coll Physicians Lond 1996;30:309-315
Medline5
Pellikka PA, Nishimura RA, Bailey KR, Tajik AJ. The natural history of adults with asymptomatic, hemodynamically significant aortic stenosis.J Am Coll Cardiol 1990;15:1012-7.
To the Editor:
The results of the enlightening study by Rosenhek et al. suggest that the degree of aortic-valve calcification and the rate of progression of aortic-jet velocity are powerful predictors of the risk of death or the need for aortic-valve replacement in asymptomatic patients with severe aortic stenosis. In her accompanying editorial, Otto1 correctly describes aortic stenosis as a disease process that leads to the insidious onset of symptoms that often go unrecognized by both the patient and the physician in spite of meticulous history taking at routine follow-up. Consequently, some patients are placed at risk for adverse clinical events such as sudden death. The foremost challenge to physicians who care for such patients is to determine the optimal timing of aortic-valve replacement.
The current American College of Cardiology–American Heart Association guidelines for the management of valvular heart disease support the use of certain findings on exercise stress testing and echocardiography to identify patients with severe aortic stenosis who are at high risk for clinical events (e.g., hypotension with exercise, the presence of left ventricular dysfunction, marked left ventricular hypertrophy, and an aortic-valve area of less than 0.6 cm2 or an aortic-valve index no higher than 0.6 cm2 per square meter of body-surface area).2 However, none of these echocardiographic findings have demonstrated the predictive power that Rosenhek et al. report for the degree of valvular calcification and the increase in aortic-jet velocity. Their results add to the existing evidence that an absence of symptoms is an insufficient reason to delay aortic-valve replacement in certain cases. The findings also shed light on the matter of which patients should be considered for early surgery.
2 ReferencesKevin E. O'Brien, M.D.
Carey L. O'Bryan, M.D.
Robert Saad, M.D.
Wilford Hall U.S. Air Force Medical Center, San Antonio, TX 782361
Otto CM . Aortic stenosis -- listen to the patient, look at the valve. N Engl J Med 2000;343:652-654
Full Text | Web of Science | Medline2
Task Force on Practice Guidelines (Committee on Management of Patients with Valvular Heart Disease)
CrossRef | Web of Science | Medline
Author/Editor Response
The authors reply:
To the Editor: We appreciate the interest of Drs. Das and Chambers in our study of patients with asymptomatic but hemodynamically severe aortic stenosis. Our data suggest that the echocardiographically determined extent of calcification of the valve and the observed rate of hemodynamic progression permit the early identification of patients at risk who should undergo surgery despite the absence of symptoms. As pointed out in our article, the patients who were followed and treated conservatively underwent surgery only when symptoms developed, not because of hemodynamic progression or a certain degree of hemodynamic severity.
The current American College of Cardiology–American Heart Association guidelines1 do not support the approach of operating on asymptomatic patients just because their stenosis is severe. According to these guidelines, valve replacement is definitely recommended in symptomatic patients only (those with a class I indication) and is probably indicated in asymptomatic patients with impaired left ventricular function or abnormal exercise response (class IIa). Although there is some controversy surrounding the matter, these guidelines state that evidence is lacking to support surgery in asymptomatic patients solely because hypertrophy is severe or because the aortic-valve area is smaller than 0.6 cm2 (a class IIb indication). The rate of progression is not mentioned at all. Thus, in a patient with an increase in aortic-jet velocity whose aortic-valve area is still at least 0.6 cm2, the guidelines would not recommend surgery.
As discussed in detail in our article, we agree with Das and Chambers that it may be difficult to distinguish between asymptomatic and mildly symptomatic patients. Finally, we also agree that exercise testing plays an important part in the treatment of asymptomatic patients. Nevertheless, there are few data addressing this issue.
1 ReferencesHelmut Baumgartner, M.D.
Raphael Rosenhek, M.D.
University of Vienna, 1090 Vienna, Austria1
Task Force on Practice Guidelines (Committee on Management of Patients with Valvular Heart Disease)
CrossRef | Web of Science | Medline
Author/Editor Response
The editorialist replies:
To the Editor: The primary factors determining the optimal timing of valve replacement for severe aortic stenosis are the relative clinical outcomes with and without surgical intervention. The observations by Rosenhek et al. that moderate-to-severe valve calcification and a rapid increase in aortic-jet velocity are associated with a higher rate of onset of symptoms are helpful in ensuring that patients with these conditions receive close clinical and echocardiographic follow-up and are educated about the expected course of disease and the probable need for valve surgery. However, one cannot extrapolate from these data the suggestion that valve replacement should be performed before the onset of symptoms in these patients.
In the absence of symptoms, the risk of sudden death is very low (less than 1 percent per year), even with severe stenosis, as confirmed by the occurrence of only 1 sudden death among 128 patients during more than two years in our prospective study. In contrast, aortic-valve replacement is associated with an operative mortality of 2 to 10 percent.1 In addition, there is no ideal substitute for the valve: the hemodynamics after valve replacement are suboptimal as compared with those associated with a normal native valve; complications occur at a rate of 2 to 3 percent per year after surgery; and it is estimated that the risk of death due to a prosthetic valve is about 1 percent per year.2-4
The American College of Cardiology–American Heart Association guidelines for the treatment of patients with valvular heart disease should continue to serve as the benchmark for the optimal care of adults with severe aortic stenosis.4 The only class I indications for valve replacement — those for which there is evidence or general agreement (or both) that the procedure is useful and effective — are severe symptomatic stenosis and severe stenosis in patients who are undergoing coronary-artery bypass grafting, aortic-root surgery, or other valve surgery. The evidence also favors valve replacement in patients with moderate aortic stenosis who are undergoing other cardiac surgery and for asymptomatic patients with severe stenosis and left ventricular systolic dysfunction or exertional hypotension. In other asymptomatic adults with severe stenosis, we should defer valve surgery until symptoms occur, because we can then be certain that our recommendation is associated with improved clinical outcomes. After all, it is difficult to make an asymptomatic patient feel better.
4 ReferencesCatherine M. Otto, M.D.
University of Washington School of Medicine, Seattle, WA 981951
Otto CM. Aortic stenosis. In: Otto CM, ed. Valvular heart disease. Philadelphia: W.B. Saunders, 1999:179-217.
2
Vongpatanasin W ,Hillis LD ,Lange RA . Prosthetic heart valves. N Engl J Med 1996;335:407-416
Full Text | Web of Science | Medline3
Hammermeister KE ,Sethi GK ,Henderson WG ,Oprian C ,Kim T ,Rahimtoola S . A comparison of outcomes in men 11 years after heart-valve replacement with a mechanical valve or bioprosthesis. N Engl J Med 1993;328:1289-1296
Full Text | Web of Science | Medline4
Task Force on Practice Guidelines (Committee on Management of Patients with Valvular Heart Disease)
CrossRef | Web of Science | Medline
