Trends in the surgical management of ischemic mitral regurgitation

Ischemic mitral regurgitation: not only a bystander

Ischemic mitral regurgitation (MR) is a common complication of left ventricular (LV) dysfunction related to chronic coronary artery disease. This complex multifactorial disease involves global and regional LV remodeling, as well as dysfunction and distortion of the components of the mitral valve including the chordae, the annulus, and the leaflets. Its occurrence is associated with a poor prognosis. The suboptimal results obtained with the most commonly used surgical strategy, involving mitral valve annuloplasty with coronary bypass grafting, emphasize the need to develop alternative surgical techniques targeting the causal mechanisms of the disease. A comprehensive preoperative assessment of mitral valve configuration and LV geometry and function and an accurate quantification of MR severity at rest and during exercise may contribute to improve risk stratification and to tailor the surgical strategy according to the individual characteristics of the patient.

Long-term outcomes of patients with mitral regurgitation undergoing percutaneous coronary intervention

The most appropriate treatment for patients with ischemic mitral regurgitation (MR) remains controversial. MR has prognostic importance in patients after myocardial infarction and those undergoing coronary artery bypass surgery, but the long-term outcomes after percutaneous coronary intervention (PCI) are less well defined. We evaluated patients who underwent PCI and had assessment of MR by left ventriculography and/or echocardiography in the year 2000. We determined effects of MR on 30-day and 5-year survival. The cohort included 711 patients (67% men) with an average age of 64.5 +/- 12.4 years. MR severity was divided into 3 strata: none (n = 420, 59%), mild (n = 209, 29%), and moderate to severe (n = 82, 12%). Patients with more severe MR differed from patients with mild or no MR in that they were older (p <0.001), more frequently women (p <0.001), and more likely to have a coronary artery bypass graft (p <0.001), myocardial infarction (p <0.001), and lower ejection fraction (p <0.001). Decreased survival rates were associated with increasing MR severity (none vs mild vs moderate to severe) at 30 days (100%, 98.7%, and 96.6%, respectively; p <0.0025) and 5 years (97%, 83.3%, and 57.5%; p <0.0001). MR was an important independent predictor of survival (hazard ratio 1.57, p <0.0009). In conclusion, patients with ischemic MR undergoing PCI have significantly decreased survival rates at 5 years, and severity of MR is an independent predictor of survival.

Is ischemic mitral regurgitation an indication for surgical repair or replacement?

Ischemic mitral regurgitation (IMR) is common in patients with coronary artery disease. While it is well-known that IMR exerts a graded effect upon survival-the greater the degree of IMR, the lower the survival-the indications for surgical treatment and the choice of surgical procedure (repair versus replacement) are controversial. In patients with mild to moderate IMR, the benefit of a mitral valve procedure has not been demonstrated, and surgical practice varies. In patients with severe IMR, mitral valve surgery is the norm, but guidelines for choosing between valve repair and valve replacement do not exist. Furthermore, the survival impact of mitral valve surgery in patients with severe IMR is uncertain. When patients with severe IMR undergo mitral valve surgery, undersized annuloplasty results in durable repair in 70% to 85% of cases. Newly-developed adjunctive repair techniques may further improve results. Currently, mitral valve repair is the procedure of choice in the majority of patients having surgery for severe IMR. However, the most severely ill patients and those with certain echocardiographic characteristics (e.g. severe bileaflet tethering) should be treated with bioprosthetic mitral valve replacement rather than repair.

Mitral regurgitation after myocardial infarction: a review

Mitral regurgitation after myocardial infarction is the result of multifactorial processes involving local and global left ventricular remodeling. The prevalence of mitral regurgitation varies from 11% to 59%. Published studies differ greatly in design, inclusion criteria, duration of follow-up, and technique of mitral regurgitation assessment. However, they consistently indicate that mitral regurgitation after myocardial infarction carries an adverse prognosis with increased risk of death and heart failure independently of previously known indicators of risk after myocardial infarction. Mitral regurgitation is often clinically silent; therefore, it should be systematically evaluated by echocardiography. Standard color Doppler imaging is a highly sensitive method to detect even mild degrees of ischemic mitral regurgitation. One unique advantage of echocardiography is that it accurately quantifies the severity of mitral regurgitation by measuring the effective regurgitant orifice area and the regurgitant volume using Doppler methodology. Therefore, the evaluation should include precise quantification of the degree of mitral regurgitation to best appraise the ensuing risk. Current medical options rely chiefly on angiotensin converting enzyme-inhibitors and beta-blocker therapy, and surgical approaches offer future promise. Both categories of therapeutic approaches should be evaluated by randomized controlled trials.

Hemodynamic Changes During Off-Pump Coronary Artery Bypass Anastomosis in Patients with Coexisting Mitral Regurgitation: Improvement with Milrinone

We hypothesized that mitral regurgitation (MR) would be exacerbated, cardiac index (CI) decreased, and mean pulmonary artery pressure (MPAP) increased in patients with coexisting MR during off-pump coronary artery bypass (OPCAB) anastomosis, and that milrinone could ameliorate increases in MR that occur during OPCAB anastomosis. Subjects comprised 140 patients scheduled for elective OPCAB divided into three groups: patients without MR (MR(-) group; n = 57), patients with MR (MR(+) group; n = 41), and patients with MR who received milrinone (M+MR(+) group; n = 42). Patients with grade 1+ or 2+ MR were included, whereas those with grade 3+ or 4+ MR were excluded. Hemodynamic variables were measured after the induction of anesthesia and during anastomosis. IV infusion of milrinone (0.5 microg . kg(-1) . min(-1)) started immediately after the induction of anesthesia in the M+MR(+) group. CI was significantly decreased (P < 0.0001), and MPAP and MR were significantly increased (P < 0.001) during left coronary anastomosis in the MR(+) group compared with the MR(-) group. CI was significantly higher (P < 0.001), and neither MPAP nor MR were increased (P < 0.05) during left coronary artery anastomosis in the M+MR(+) group compared to the MR(+) group. In patients with MR, anastomosis of the left coronary artery branches was associated with decreased CI and increased regurgitation and MPAP. In such patients, treatment with milrinone helps to stabilize hemodynamics during anastomosis.