Management of mitral regurgitation. Optimal timing for surgery

Mitral regurgitation: determinants of referral for cardiac surgery by Canadian cardiologists

PURPOSE

Advances in surgery permit for earlier intervention with improved outcomes for patients with mitral regurgitation (MR). Many patients still appear to be referred to surgery late in their course. Consensus guidelines were compared with the surgical referral practices for MR among Canadian cardiologists.

METHODS

A self-administered questionnaire was mailed to all adult cardiologists in Canada. This included seven case scenarios, as well as direct questions designed to establish the influence of factors including atrial fibrillation, pulmonary hypertension, left ventricular (LV) dilation, experience of the cardiac surgeon, symptoms and ejection fraction (EF) on referral.

RESULTS

There were 319 respondents; LVEF was rated as extremely important in 71.5% of patients and moderately important in 26% of patients. In asymptomatic patients, EF of 50% to 60% was correctly identified as a trigger for surgery by 57.2 % of cardiologists, while only 15.6% of cardiologists correctly referred New York Heart Association class II patients with normal LV function. The group complied in only 4.77 of the seven case scenarios. Compliance was inversely related to years in practice for asymptomatic patients with mild LV dysfunction, as well as in overall compliance. Referral practices were similar among clinicians, echocardiographers, interventional cardiologists and researchers, with no differences in geographic region or academic affiliation.

CONCLUSION

Compliance with published guidelines for patients with MR and either New York Heart Association class II or mild LV dysfunction among Canadian cardiologists was poor. Compliance was somewhat better in more recent graduates, suggesting the need to institute programs geared at enhancing knowledge of published standards and introduce practical tools to aid in their implementation.

Cardiopulmonary exercise testing before and one year after mitral valve repair for severe mitral regurgitation

For the evaluation of efficacy of cardiopulmonary exercise testing, we compared New York Heart Association functional class with peak oxygen consumption rate (VO(2)peak) in 31 patients with severe mitral regurgitation who underwent mitral valve repair surgery. One year later, the VO(2)peak values did not show significant improvement; however, the patients who had more than a mild degree of residual mitral regurgitation (n = 14) after 1 year of surgery had a VO(2)peak value that was significantly decreased (from 22.7 +/- 6.4 to 21.0 +/- 6.3 ml/kg/min, p = 0.04). Patients with a higher preoperative VO(2)peak value (>/=18.5 ml/kg/min) had a significantly better New York Heart Association functional class 1 year after surgery than patients with a lower VO(2)peak value (<18.5 ml/kg/min, p = 0.03).

Use of tissue Doppler echocardiography in early detection of left ventricular systolic dysfunction in patients with mitral regurgitation

OBJECTIVE

Left ventricular ejection fraction (EF) and left ventricular (LV) end-systolic diameter measurements are the most widely accepted and utilized methods to demonstrate LV dysfunction in patients with mitral regurgitation (MR). However, these parameters still have many drawbacks in predicting early LV dysfunction. This study investigates the clinical usefulness of tissue Doppler echocardiography technique in detecting early disturbance of myocardial contractility in asymptomatic patients with chronic, severe MR and normal LV ejection fraction values.

METHODS AND RESULTS

Regional systolic peak velocities of mitral annular motion during the ejection phase of systole (SW2) were obtained at the mitral annuli of the ventricular septal, lateral, anteroseptal, posterior, anterior and inferior wall sites in the long axis in 31 asymptomatic patients with severe MR (with a regurgitant volume of more than 50 ml) and with EFs more than 60%. The patients were grouped according to their dP/dt values (more or less than 1300 mmHg/s) estimated non-invasively by using continuous Doppler wave of MR SW2 measurements of Group I were higher than Group II in all of the analyzed segments. The difference was statistically significant for all of the segments. SW2 values of the whole study group was moderately correlated with dP/dt measurements in all of the analyzed segments other than the interventricular septum.

CONCLUSION

SW2 measurements in the long axis, which are considered to be relatively independent from afterload conditions may be helpful in early detection (while EF is still in normal range) of LV systolic dysfunction during the follow-up of patients with chronic MR.

The role of cardiopulmonary exercise test in mitral and aortic regurgitation: it can predict post-operative results

BACKGROUND

We evaluated the efficacy of the cardiopulmonary exercise test as an objective indicator of functional status and as a pre-operative prognostic indicator in patients with mitral regurgitation (MR) and aortic regurgitation (AR).

METHODS

Cardiopulmonary exercise tests and echocardiography were performed in 47 patients (MR: 30, AR: 15, MR + AR: 2) before surgery and repeated one year after surgery. We compared the New York Heart Association (NYHA) functional class, peak oxygen consumption rate (VO2peak), exercise duration, left ventricular dimension and ejection fraction, before and after surgery.

RESULTS

Initial VO2peak and exercise duration were significantly different according to NYHA class. A year later, NYHA functional class improved from 2.1 +/- 0.1 to 1.4 +/- 0.1 (p < 0.001). The VO2peak was significantly increased (21.7 +/- 1.0 to 23.7 +/- 1.0 mL/kg per min, p = 0.008) and exercise duration also increased (521.7 +/- 35.9 to 623.3 +/- 35.7 seconds, p < 0.001). When patients were analysed according to their post-operative NYHA functional class, those with class I showed significantly different pre-operative VO2peak (class I: 23.7 +/- 1.1, II: 18.3 +/- 1.5 mL/kg per min, p = 0.005) and exercise durations (class I: 587.5 +/- 43.2, II: 415.6 +/- 55.7 seconds, p = 0.02). Patients with higher pre-operative VO2peak (19.0 mL/kg per min) more frequently became NYHA functional class I than those with a lower pre-operative VO2peak (76.7% vs. 35.3%, p = 0.02). But baseline left ventricular dimension and ejection fraction by echocardiography were not different between post-operative class I and II group.

CONCLUSION

VO2peak and exercise duration are excellent parameters to evaluate the subjective functional class and to predict the post-operative functional class of patients with MR and/or AR. Patients with a pre-operative VO2peak of 19.0 mL/kg per min or more will have a better functional status one year after surgery.

Prophylactic mitral reconstruction for mitral regurgitation

BACKGROUND

Mitral regurgitation (MR) will produce myocardial dysfunction. The goal of this study was to review outcomes of mitral valve reconstruction in asymptomatic patients with severe MR.

METHODS

From 1992 to 2000, 93 asymptomatic patients with degenerative disease and severe MR underwent mitral valve reconstruction. Mean preoperative left ventricular internal diameter diastole was 56 +/- 8 mm and ejection fraction was 60% +/- 6%. Mean age was 47 +/- 10 years and mean follow-up 23 +/- 27 months. All patients underwent complex reconstruction.

RESULTS

There were no deaths and two late reoperations. One was for systolic anterior motion of the anterior leaflet of the mitral valve requiring valve replacement and one for hemolysis requiring re-repair. There was one perioperative transient ischemic attack and no late thromboembolic events. At follow-up all but 1 patient remains in NYHA class I and all had no MR except in 2 patients at 63 and 89 months.

CONCLUSIONS

Mitral valve reconstruction for "asymptomatic" MR can be performed with no mortality and low morbidity before development of left ventricular dysfunction. Early prophylactic repair is advocated in the presence of severe MR if valve reparability is assured.

Improvement in right ventricular systolic function after surgical correction of isolated tricuspid regurgitation

Chronic tricuspid regurgitation (TR) may lead to impairment in right ventricular (RV) function. Whether surgical correction results in restoration of normal RV geometry and function is unknown. The purpose of this study was to determine whether surgical correction of TR results in improved RV geometry and function. Measurements of RV areas were made from digitized 4-chamber echocardiographic views. Right ventricular end-diastolic volume (RVEDV), right ventricular end-systolic volume (RVESV), and ejection fraction (EF) were calculated with the single-plane subtraction method. There was a significant decrease in RVEDV (109.06 +/- 12.45 versus 71.63 +/- 6. 83; P =.005) and RVESV (76.2 +/- 9.83 versus 44.5 +/- 5.58; P =.002) and a significant increase in RVEF (0.30 +/- 0.05 versus 0.38 +/- 0. 05; P =.01) at a mean follow-up of 130 +/- 63 days after surgery. These results demonstrate significant remodeling of the right ventricle with reduction in size and improved EF after tricuspid valve surgery.