Timing of Surgery for Patients With Nonischemic Severe Mitral Regurgitation
Amajor problem in the management of patients with chronic, severe mitral regurgitation (MR) remains the timing of operative intervention. This is particularly true for patients with nonischemic severe MR, which in the United States is now most often due to mitral valve prolapse, frequently with a flail mitral leaflet. Surprisingly, some patients with this condition do not have undue fatigue or dyspnea during ordinary physical activity and therefore are in NYHA functional class I.1 Patients are classified as functional class II when they have slight limitation of physical activity and are comfortable at rest. Ordinary physical activity results in fatigue, palpitation, dyspnea, or anginal pain. Patients are classified as functional class III when they have cardiac disease that results in marked limitation of physical activity; although patients in functional class III are comfortable at rest, less-than-ordinary physical activity causes fatigue, palpitation, dyspnea, or anginal pain. Patients are classified as functional class IV when their cardiac disease results in inability to carry on any physical activity without discomfort. Symptoms of heart failure or of the anginal syndrome may be present even at rest and may increase if any physical activity is undertaken.
It is significant that this functional classification is based entirely on subjective symptoms. This was one of the reasons why this functional classification described in the sixth edition (1964) was replaced in the seventh (1973) and eighth (1979) editions of the NYHA Nomenclature and Criteria for Diagnosis of Diseases of the Heart and Great Vessels. The most recent edition (1994)1 restored the original functional classification, which has been widely used by the medical profession despite its subjectivity and unproven reproducibility.
In this issue of Circulation, Tribouilloy and colleagues present an elegant retrospective analysis of patients who underwent surgical correction of organic (nonischemic) MR at the Mayo Clinic.2 Although this was a retrospective analysis and the patients were not randomized to surgery or medical therapy, the authors conclude that patients with functional class III or IV symptoms had increased short- and long-term mortality independent of baseline characteristics. The authors further conclude that surgical correction of organic MR of severe degree is indicated even when no or minimal symptoms are present.
Several aspects of their review are especially noteworthy. Patients were excluded if they had associated mitral stenosis or required aortic or tricuspid valve replacement, if their MR was thought to be due to ischemic heart disease or cardiomyopathy, if they had previous valve repair or replacement, or if there was associated congenital heart or pericardial disease.
The cause of the MR in this series was mitral valve prolapse in 379 (79.3%), rheumatic in 39 (8.2%), endocarditis in 39 (8.2%), and miscellaneous in 21 (4.4%). Surgical repair of the mitral valve was performed in 323 patients (67.6%) and valve replacement in only 155 (32.4%). Of note, CABG was performed in 130 patients (27.2%) in association with the valve surgery.
Many of the patients included in this review have been included in previous articles from the Mayo Clinic.3 4 5 6 It should be emphasized that 79.2% of the patients in the present analysis had mitral valve prolapse, usually with a flail mitral valve leaflet. The surgical management of this condition has also been previously reviewed by Mayo physicians.7 8
It would have been useful to have data on patients seen at the Mayo Clinic between 1984 and 1991 who were found to have severe organic, isolated MR but who did not undergo surgery. In addition, an exercise function test would probably have provided more objective data regarding functional limitation, often more accurately than the usual NYHA functional classification.
The authors are careful to emphasize that the operative risk for patients with severe MR who are asymptomatic should be reviewed for each institution. They note that the operative risk today is extraordinarily low, 0.5% for all ages9 and 0% for patients <75 years old. In patients >75 years old, the operative risk was only 3.6% for their patients in class I or II but rose to 12.7% for patients with severe symptoms. They found that their patients operated on in NYHA functional class I or II had a long-term postoperative survival equivalent to expected survival.
The authors confirmed that mitral valve repair rather than mitral valve replacement was the preferred mode of correction of MR and concluded that this was now feasible in ≈84% of patients. Thus, to achieve the benefits of early repair, there should be a strong likelihood of valve repair and the surgeon should be highly skilled in mitral valve repair surgery. It is not surprising that they felt that some asymptomatic elderly patients, who may incur a higher operative risk, should be followed conservatively while waiting for the development of class II symptoms.
This extensive experience at the Mayo Clinic can be incorporated into the lessons from numerous other studies to develop new principles and options of management for patients with severe MR due to mitral valve prolapse, with or without a flail mitral leaflet.10
Patients with chronic nonischemic severe MR who have NYHA functional class I symptoms and who have normal left ventricular (LV) function (LV ejection fraction [LVEF]>0.60 and LV end-systolic diameter [LVESD] <45 mm) may be followed up medically at frequent (3- to 6-month) intervals. If such patients develop evidence of LV dysfunction, atrial fibrillation, or pulmonary hypertension (estimated pulmonary artery pressure of 50 mm Hg at rest or 60 mm Hg during exercise), the patient should be considered for cardiac catheterization and possible mitral valve surgery, particularly if it is thought that the mitral valve can be repaired.10 On the basis of the Mayo Clinic experience, one can consider mitral valve surgery even if the patient has only NYHA class I symptoms, particularly in the presence of a flail mitral valve leaflet if the patient has access to extremely qualified mitral valve surgery.
Patients who have chronic nonischemic severe MR who have class II, III, or IV symptoms should be considered for mitral valve surgery whether or not the LV function is normal (LVEF>0.60, LVESD <45 mm).10 Whenever possible, mitral valve repair should be performed. Conversely, patients with severe symptoms and severely depressed LV function (LVEF <0.30) are generally best treated medically.
The physician caring for patients with chronic severe nonischemic MR today clearly has more options in management. The greater number of factors that should be considered in the decision to recommend mitral valve surgery will obviously vary with each patient and in each hospital.
The opinions expressed in this editorial are not necessarily those of the editors or of the American Heart Association.
- Copyright © 1999 by American Heart Association
Dolgin M (ed), and the Criteria Committee of the New York Heart Association. Nomenclature and Criteria for Diagnosis of Diseases of the Heart and Great Vessels. 9th ed. Boston, Mass: Little, Brown & Co; 1994.
Tribouilloy CM, Enriquez-Sarano M, Schaff HV, Orszulak TA, Bailey KR, Tajik AJ, Frye RL. Impact of preoperative symptoms on survival after surgical correction of organic mitral regurgitation: rationale for optimizing surgical indications. Circulation. 1999;99:400–405.
Enriquez-Sarano M, Tajik AJ, Schaaf HV, Orszulak TA, Bailey KR, Frye RL. Echocardiographic prediction of survival after surgical correction of organic mitral regurgitation. Circulation. 1994;90:830–837.
Enriquez-Sarano M, Schaff HV, Orszulak TA, Bailey KR, Tajik AJ, Frye RL. Congestive heart failure after surgical correction of mitral regurgitation: a long-term study. Circulation. 1995;92:2496–2503.
Enriquez-Sarano M, Schaff HV, Orszulak TA, Tajik AJ, Bailey KR, Frye RL. Valve repair improves the outcome of surgery for mitral regurgitation: a multivariant analysis. Circulation. 1995;91:1022–1028.
Ling LH, Enriquez-Sarano M, Seward JB, Orszulak TA, Schaff HV, Bailey KR, Tajik AJ, Frye RL. Early surgery in patients with mitral regurgitation due to flail leaflets: a long-term outcome study. Circulation. 1997;96:1819–1825.
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