Society of Cardiovascular Anesthesiologists

Mitral valve surgery for chronic ischemic mitral regurgitation.

Calafiore AM, Di Mauro M, Gallina S, Di Giammarco G, Iaco AL, Teodori G, Tavarozzi I. Ann Thorac Surg 77:1989-97, 2004.

Reviewer: Mark A. Chaney, MD
Associate Professor
University of Chicago

Abstract Excerpt: While there is general agreement that the presence of ischemic mitral regurgitation (IMR) has a negative influence on survival, the necessity of correction is questioned and technique of correction (revascularization?, repair?, replacement?) is not yet standardized. These investigators evaluated their early and midterm clinical and echocardiographic results following mitral valve surgery for chronic IMR and the validity of their criteria for valve repair or valve replacement. From 1988 to 2002, 102 patients with IMR underwent mitral valve surgery (82 repairs, 20 replacements). End-systolic distance between the coaptation point of mitral leaflets and the plane of the mitral annulus was the key factor determining either repair (≤ 10 mm) or replacement (>10 mm). Patients who had mitral valve replacement showed a higher New York Heart Association class (3.2 ± 0.5 versus 3.4 ± 0.5; p = 0.016), lower preoperative ejection fraction (33% ± 9% versus 38% ± 12%; p = 0.034), and a higher end-diastolic volume (161 ml ± 69 ml versus 109 ml ± 35 ml; p < 0.001) compared with repair. Grade of mitral regurgitation was 3.2 ± 0.7 in both groups. Thirty-day mortality was 3.9% (2.4% repair versus 10.0% replacement; not significant). During follow-up, 26 patients died. Of 72 survivors, 55 (76%) were in New York Heart Association classes I and II. Five-year survival was 75.6% ±4.7% in the repair group and 66.0% ± 10.5% in the replacement group (not significant). Survival in New York Heart Association classes I and II was 58.9% ± 5.4% in the repair group and 40.0% ± 11.0% in the replacement group (not significant). Cox analysis identified preoperative New York Heart Association class, ejection fraction, end-diastolic volume, end-systolic volume, and congestive heart failure as risk factors common to both repair and replacement. In 46 patients (40 repair, 6 replacement), late (24 months ± 21 months) echocardiograms revealed no volume or ejection fraction modifications. In patients who underwent mitral valve repair, 50% had no or mild mitral regurgitation. These investigators conclude that correction of chronic IMR through either repair or replacement provides a good five-year survival rate, with more than 75% of the survivors in New York Heart Association classes I and II.

Comment: Mitral regurgitation that follows myocardial infarction has an incidence of approximately 20%; incidence is higher after inferior (38%) as compared with anterior (10%) myocardial infarction. In most cases, the mechanism of IMR is related to local left ventricular remodeling, with papillary muscle displacement producing apical tethering or tenting of the leaflets (restricted systolic leaflet motion). When global left ventricular dilation occurs, both papillary muscles are displaced posteriorly, laterally, and apically. As a consequence, the tethering forces on both leaflets increase, reducing their movement. Patients with IMR have a worse natural history than patients without IMR.

In spite of clear data indicating that IMR has a negative influence on survival, the necessity of correction is questioned by surgeons and technique of correction (revascularization?, repair?, replacement?) is not yet standardized. Current evidence indicates that in patients with coronary artery disease, when left ventricular function is reduced (low ejection fraction) and heart failure symptoms are present, IMR should be corrected with some type of mitral valve repair/replacement. It appears that under these circumstances, revascularization alone does not avoid early progression of IMR to more severe degrees, whereas mitral valve surgery will stabilize the amount of residual mitral regurgitation.

As echocardiography continues to progress technologically, we are now in a position to more fully understand the mechanisms of IMR. These investigators add to the growing amount of literature defining the clinical benefits of extensive surgical correction of chronic moderate-to-severe IMR. In cases of moderate IMR, mitral valve surgery appears to be indicated in the presence of low ejection fraction or large left ventricular volumes. Revascularization alone is not able to control the postoperative natural history of untreated mitral regurgitation. As cardiac anesthesiologists, we will thus continue to play a vital role in delivering high quality information to cardiac surgeons regarding the mitral valve and left ventricular function via transesophageal echocardiography in order to determine the appropriate surgical therapy.

Table of Contents:

PRO/CON: Transesophageal Echocardiography (TEE) should be used routinely in all high risk noncardiac surgery

Pro - Feroze Mahmood, MD
Con - John E. Ellis, MD

Literature Reviews
- Mitral valve surgery for chronic ischemic mitral regurgitation (Mark A. Chaney, MD)
- Plasma B-type natriuretic peptide levels predict postoperative atrial fibrillation in patients undergoing cardiac surgery (Mohammed M. Minhaj, MD)
- Severity of illness and risk of death associated with pulmonary artery catheter use (Michael H. Wall, MD)
- Cardiac replacement with a total artificial heart as a bridge to transplantation (K.W. Tim Park, MD)