Abstract & Commentary
Comment by Harold L Karpman, MD, FACC, FACP, Clinical Professor of Medicine, UCLA School of Medicine, and Associate Editor of Internal Medicine Alert
Synopsis: Patients with an effective regurgitant orifice of at least 40 mm2 should promptly be considered for cardiac surgery.
Source: Enriquez-Sarano M, et al. N Engl J Med. 2005;352: 875-883.
In most medical centers, the timing of surgery for asymptomatic primary mitral valve regurgitation has been based on both the appearance of significant symptomatology and the hemodynamic effects of the lesion (ie, the response of the left ventricle to chronic volume overload).1 The timing of surgical intervention is critical since frequently, by the time any symptoms occur, irreversible left ventricular systolic dysfunction may already have developed after which surgical outcomes are frequently quite poor and the patient may be left with persistent symptoms of left ventricular dysfunction and progressive heart failure even if surgery is performed.
Enriquez-Sarano and colleagues at the Mayo Clinic prospectively studied 456 patients with an ejection fraction of at least 50% with asymptomatic isolated (ie, without aortic valve disease) and pure (ie, without significant stenosis) mitral regurgitation due to organic valve disease identified by echocardiography.2 Independent determinants of survival were increasing age, the presence of diabetes and an increasing effective regurgitant orifice, a measurement which was found to have a predictive power that superseded all other qualitative and quantitative echocardiographic measures of mitral regurgitation. Finding an effective regurgitant orifice of at least 40 mm2 proved to be a powerful predictor of the clinical outcome of patients with mitral regurgitation in that significantly improved survival occurred in this group of patients when subjected to mitral valve replacement and/or repair even if asymptomatic before surgery.
Comment
It now appears that we must we rethink our approach to the follow-up and treatment of patients with asymptomatic chronic mitral regurgitation. Patients with symptomatic severe mitral regurgitation usually require surgical intervention; however, once left ventricular contractility has become impaired, symptoms of ventricular dysfunction and progressive heart failure may persist even after surgery has been performed. The data from the landmark Enriquez-Sarano study strengthen the concept that asymptomatic mitral regurgitation is a serious illness with a 5-year rate of death from any cause of 22% and a 33% incidence of adverse cardiovascular events including death from cardiac causes, heart failure and new onset of atrial fibrillation. Focusing on regurgitant severity as a predictor of clinical outcome in patients with primary mitral regurgitation, the data demonstrated that patients with an effective regurgitant orifice area of greater then 40 mm2 had more than 5 times the risk of death from cardiac events (ie, death from cardiac causes, congestive heart failure, or new onset atrial fibrillation) then did those patients with a regurgitant orifice area of < 20 mm2.
In summary, in appropriately selected patients, mitral valve surgery is associated with a considerably decreased risk of mortality and heart failure2 and it now appears that even after correcting for age, sex, presence or absence of diabetes and atrial fibrillation at baseline, and ejection fraction, assessment of mitral regurgitation by determining the effective regurgitant orifice provides a powerful predictor of the clinical outcome among patients with isolated, asymptomatic organic mitral regurgitation. Certainly, patients with an effective regurgitant orifice area of 40 mm2 or more should be at least monitored more closely and, in fact, since surgery in these patients often results in a normalization of life expectancy,3 surgery should be strongly considered especially if the likelihood is that the valve can be repaired rather than replaced based upon the echocardiographic findings.4 However, if valve replacement is likely to be needed or the surgical risk is high because of age and/or the presence of significant comorbid conditions, watchful waiting and careful follow-up may be a more appropriate choice. Final answers to this dilemma will come when a prospective, randomized, clinical study comparing the early surgery in asymptomatic patients with effective regurgitant mitral orifice areas of greater than 40 mm2 with a group of patients whose surgery was performed based upon conventional indications, usually after they became symptomatic. But, for the time being, physicians should strongly consider sending asymptomatic mitral regurgitation patients with mitral orifice areas of greater than 40 mm2 to surgery before they become symptomatic.
References
1. ACC/AHA guidelines for the management of patients with valvular heart disease. J Am Coll Cardiol. 1998;32:1486-1588.
2. Ling LH, et al. Circulation. 1997;96:1819-1825.
3. Tribouilloy CM, et al. Circulation. 1999;99:400-405.
4. Enriquez-Sarano M, et al. J Am Coll Cardiol. 1999;34: 1129-1136.
Patients with an effective regurgitant orifice of at least 40 mm2 should promptly be considered for cardiac surgery.
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