Usefulness of left atrial and left ventricular chamber sizes as predictors of the severity of mitral regurgitation

Preoperative left atrial volume index is associated with postoperative outcomes in mitral valve repair for chronic mitral regurgitation

OBJECTIVE

To assess determinants of left atrial reverse remodeling after mitral valve repair and to evaluate the impact of preoperative left atrial volume on postoperative outcomes.

METHODS

We reviewed the records of 720 patients who underwent mitral valve repair from September 2008 to July 2015 and had preoperative measurement of left atrial volume index. We analyzed the association of preoperative left atrial volume index on early and late outcomes, and determined which baseline characteristics are associated with left atrial reverse remodeling, as measured by changes in left atrial volume index in 512 patients who had at least 1 postoperative measurement.

RESULTS

The median (interquartile range) preoperative left atrial volume index was 54.0 (44.0-66.0) mL/m². Preoperative left atrial volume index, age, body mass index, and atrial fibrillation were independently associated with the degree of left atrial reverse remodeling over the follow-up period. Reverse remodeling was greatest in patients with higher baseline left atrial volume index (P < .001), but less reverse remodeling was observed in patients with advanced age (P < .001), preoperative atrial fibrillation (P < .001), and extreme values of body mass index (P = .004), although these effects were moderately attenuated when limiting the analysis to 6-month follow-up. Secondary analysis demonstrated marginally significant effects of preoperative left atrial volume index on risks of early postoperative atrial fibrillation (P = .030) and late mortality (P = .077) after adjusting for age and sex.

CONCLUSIONS

In patients with degenerative mitral valve regurgitation who had mitral valve repair, preoperative left atrial volume index was associated with extent of left atrial reverse remodeling, risk of early postoperative atrial fibrillation, and late mortality. The majority of reverse remodeling occurs within the first month after operation and is greatest in younger patients.

Early mitral regurgitation after acute myocardial infarction does not contribute to subsequent left ventricular remodeling

BACKGROUND

It is well known that mitral regurgitation may lead to left ventricular dilation; however, the relationship between progressive left ventricular dilation after acute myocardial infarction (MI) and mitral regurgitation has not yet been clarified.

HYPOTHESIS

This study tested the hypothesis that early mitral regurgitation contributes to left ventricular remodeling after acute MI.

METHODS

We prospectively evaluated 131 consecutive patients by serial two-dimensional and Doppler echocardiography on Days 1, 2, 3, and 7, after 3 and 6 weeks, 3 and 6 months, and 1 year following acute MI. Patients were divided into two groups: those with mitral regurgitation in the first week after acute MI (Group 1, n = 34) and those without mitral regurgitation (Group 2, n = 81).

RESULTS

Over 1 year, a significant increase in end-diastolic volume index (from 62.1 +/- 12.9 to 70.5 +/- 23.6 ml/m2, p = 0.001) with a strong linear trend (F = 15.1, p < 0.001) was noted. Initial end-diastolic volume index was higher in Group 1 (65.6 +/- 13.3 vs. 60.4 +/- 12.5 ml/m2, p = 0.047), but this difference remained constant throughout the study (F = 1.76, p = NS). Therefore, the pattern of end-diastolic volume changes was similar in both groups during the period of observation.

CONCLUSIONS

These data indicate that early mitral regurgitation after acute MI does not contribute to subsequent left ventricular remodeling in the first year after myocardial infarction.

Enlarged Left Atrial Volume in Hypertrophic Cardiomyopathy: A Marker for Disease Severity

BACKGROUND

Patients with hypertrophic cardiomyopathy and left atrial (LA) enlargement have increased morbidity and mortality. We analyzed the clinical and echocardiographic factors related to LA enlargement, particularly the degree of left ventricular (LV) hypertrophy and diastolic function.

METHODS

A total of 104 patients with hypertrophic cardiomyopathy (age 53 +/- 15 years, 64% men) were divided into two groups based on the indexed LA volume (LAVI) (mL/m2) measured by echocardiography: group A (or smaller LAVI group, n = 43) was defined as LAVI < or = 34 mL/m2; and group B (or larger LAVI group, n = 61) as LAVI > 34 mL/m2. Detailed clinical and echocardiographic data were obtained. LV wall thickness was measured at 15 sites at 3 levels (base, mid, and apex). Diastolic function was assessed from mitral and pulmonary venous inflow velocities and Doppler tissue imaging.

RESULTS

Both groups were similar in terms of sex, functional class (1.6 +/- 0.8 vs 1.5 +/- 0.8, group B vs A, P = .64), and incidence of atrial fibrillation (13% vs 5%, P = .19). However, patients of group B had a significantly higher incidence of serious cardiovascular events (16.4% vs 2.3%, group B vs A, P = .024). Both groups had a similar degree of resting LV outflow tract obstruction (19 +/- 30 vs 12 +/- 13 mm Hg, group B vs A, P = .06). However, those in group B had a higher incidence of at least moderate mitral regurgitation (25% vs 5%, group B vs A, P = .007), more LV hypertrophy at 6 LV nonapical wall segments (P < .05-P < .001), and a higher hypertrophy (Wigle) score (6.2 +/- 2.2 vs 4.5 +/- 2.1, group B vs A, P < .001). In addition, patients of group B had a higher incidence of abnormal diastolic filling (57% vs 28%, group B vs A, P = .003), a higher early diastolic velocity/early diastolic mitral annular velocity (10.2 +/- 4.9 vs 7.5 +/- 2.9, group B vs A, P = .003), and a higher calculated LA pressure (14.8 +/- 6.5 vs 11.1 +/- 3.4 mm Hg, group B vs A, P = .0011).

CONCLUSIONS

Patients with hypertrophic cardiomyopathy and LA enlargement had more serious cardiovascular events and demonstrated greater LV hypertrophy, more diastolic dysfunction, and higher filling pressures.

Effect of enalapril on left ventricular diameters and exercise capacity in asymptomatic or mildly symptomatic patients with regurgitation secondary to mitral valve prolapse or rheumatic heart disease

The effects of 12 months of therapy were evaluated in 47 mildly symptomatic patients with moderate to severe mitral valve regurgitation; 26 patients received enalapril and 21 received a placebo. Enalapril was associated with a significant reduction in left ventricular diameter and mitral regurgitation volume, with no evidence of change in systolic function indexes. However, enalapril did not hinder progressive aerobic impairment to effort.

B-Type Natriuretic Peptide in Organic Mitral Regurgitation

Background— B-type natriuretic peptide (BNP) activation observed in cardiac diseases is a predictor of poor outcome; however, in organic mitral regurgitation (MR), BNP determinants and prognostic value are unknown.

Methods and Results— We prospectively enrolled 124 patients with chronic organic MR (aged 63±15 years, 60% males) in whom we measured BNP level and simultaneously quantified MR degree, left ventricular (LV) remodeling, and left atrial (LA) volumes and analyzed long-term outcome. Baseline BNP level (54±67 pg/mL, median 31 pg/mL) was associated univariately with multiple clinical and echocardiographic characteristics, but in multivariate analysis, independent determinants of BNP, beyond age and sex (both P ≤0.01), were LV end-systolic volume index, LA volume, atrial fibrillation, and symptoms (all P <0.02). Conversely, MR degree was not independently associated with BNP. During follow-up, patients with high versus low BNP (≥31 versus <31 pg/mL) displayed lower survival rates (at 5 years, 72±10% versus 95±5%, P =0.03) and higher rates of the combined end point of death and heart failure (at 5 years, 42±10% versus 16±7%, P =0.03). In multivariate analysis, with adjustment for age, sex, functional class, MR severity, and ejection fraction, BNP was independently predictive of mortality (hazard ratio per 10 pg/mL, 1.23 [95% CI 1.07 to 1.48], P =0.004) and of death or heart failure (hazard ratio per 10 pg/mL, 1.09 [95% CI 1.001 to 1.19], P =0.04).

Conclusions— BNP activation in organic MR reflects primarily ventricular and atrial consequences rather than degree of MR. Higher BNP level in patients with organic MR independently predicts adverse events under conservative management. Therefore, BNP activation in organic MR is an emerging biomarker of severity of MR consequences and of poor clinical outcome, and its assessment should be considered in the clinical evaluation and risk stratification of patients with MR.

[Current standard in diagnosis and therapy of heart valve lesions]

We present a survey of the current standard in diagnosis and therapy of the most frequent heart valve lesions. During the last 50 years there has been a dramatic shift concerning the etiology of valve lesions with a rise of the agedependent degenerative towards rheumatic valve diseases. The aim of the diagnostic evaluation of valve lesions is primarily the clinical and hemodynamic grading of the severity of the valve disease, the recognition of relevant coexisting cardiac and extracardiac diseases and furthermore, an optimal timing of surgery in close correlation with the cardiac surgeons.

Left atrial volumes assessed by three- and two-dimensional echocardiography compared to MRI estimates

OBJECTIVES

The aim of the present study was to establish the accuracy and reproducibility of left atrial volume measurements by three-dimensional (3D) echocardiography compared to 2D biplane and monoplane measurements.

BACKGROUND

No echocardiographic technique is generally accepted as optimal for estimation of left atrial size.

METHODS

Left atrial volumes of 18 unselected cardiac patients were obtained with magnetic resonance imaging (MRI) (volumes 145 +/- 58 ml). These volumes were compared with those obtained with different echocardiographic methods: a multiplane 3D method based on 90 images acquired by apical probe rotation, a simplified 3D method using only the three standard apical views, and 2D biplane and monoplane methods based on area-length, disc summation and spherical formulas.

RESULTS

The echocardiographic methods significantly underestimated maximum left atrial volumes as obtained by MRI by 14-37% (p < 0.001). Accuracy, expressed as 1 SD of individual estimates around this systematic underestimation, was 25 to 27% for all methods, except for the 2D 2-chamber monoplane method (37%). Interobserver coefficient of variation was between 14 and 20% for all methods (n.s.).

CONCLUSION

All echocardiographic methods significantly underestimated left atrial volumes as obtained by MRI. A minor non-significant improvement in individual echocardiographic estimates by the 3D methods was obtained at the cost of more time consumption. In unselected patients ultrasound image quality precludes significant improvement of left atrial volume measurements by the applied 3D methods.

Clinical application of transthoracic volume-rendered three-dimensional echocardiography in the assessment of mitral regurgitation

Two-dimensional echocardiography (2-DE) and Doppler methods are generally used for assessing mechanisms and severity of mitral regurgitation (MR). Recently, 3-dimensional echocardiography (3-DE) has been applied successfully in various cardiac disorders, but its value in evaluating the mechanism and the severity of MR are not known. We studied 30 patients with MR using 2-DE and 3-DE. Volume-rendered gray-scale 3-DE images of the mitral valve apparatus and MR jets were reconstructed. Maximal volume of the MR jet by 3-DE was compared with mitral regurgitant volume and fraction, regurgitant jet area and the ratio of jet area to left atrial area, and semiquantitative grading derived from 2-DE methods. Our results demonstrated that 3-DE aided in a better depiction of the mitral apparatus and its abnormalities in 70% of the patients. The origin, direction, and morphology of the MR jet were better delineated in 3-DE volumetric display. Quantitative analysis, however, showed only a weak to moderate correlation between 3-DE maximal MR jet volume and 2-DE mitral regurgitant volume (y = 0.5x + 11.4, r = 0.7), regurgitant fraction (y = 0.5x + 8.2, r = 0.65), mitral regurgitant jet area (y = 0.2x + 5, r = 0.51), jet area to left atrial area ratio (y = 0.53x + 7.6, r = 0.54), and semiquantitative grading of MR (y = 9.1x - 1.8, r = 0.74). In conclusion, 3-DE aids in a better understanding of the mechanisms of MR and morphology of the regurgitant jets. Its quantitative ability, when reconstruction of the jet alone is used, may be limited.

Relationship between degree of mitral protrusion assessed by use of B-mode echocardiography and degree of mitral regurgitation using an experimental model in dogs

We studied the relationship between the degree of mitral protrusion and degree of mitral regurgitation in an experimental model in which the degree of mitral protrusion could be adjusted. The model was developed by dissecting the dorsal papillary muscle through a left atriotomy in 5 dogs and re-attaching the papillary muscle to the original site using a single mattress suture threading through the epicardium under cardiopulmonary bypass. By manipulating the suture from a position outside the epicardium, the degree of mitral protrusion could be adjusted. The long-axis view of the mitral valve was imaged by B-mode echocardiography with the transducer placed directly over the surface of the right ventricular outflow tract. The height (H) from the coaptation point or tip of the protruded cusp in relation to the mitral annular plane was measured as an index of mitral protrusion. Mitral regurgitation as a result of the mitral protrusion decreased the left ventricular systolic pressure, and increased the heart rate, mean left atrial pressure (LAPm), and ratio of left ventricular end-diastolic dimension to body weight (LVEDD/BW). H was negatively correlated to LAPm and LVEDD/BW (r = -0.723 and -0.697, respectively). Our results indicated that H expresses not only the degree of mitral protrusion but also the degree of mitral regurgitation, and were in agreement with the previous findings obtained on dogs with spontaneous mitral regurgitation.

Clinical outcome of mitral regurgitation due to flail leaflet

BACKGROUND

Mitral regurgitation due to flail leaflet is difficult to manage, because it is frequently asymptomatic yet carries a high risk of left ventricular dysfunction and because the natural history of the condition is poorly defined.

METHODS

We obtained clinical follow-up data through 1994-1995 in 229 patients with isolated mitral regurgitation due to flail leaflet; this condition was first diagnosed by echocardiography between 1980 and 1989.

RESULTS

The 86 patients who were treated medically had a mortality rate significantly higher than expected (6.3 percent yearly, P=0.016 for the comparison with the expected rate in the U.S. population according to the 1990 census). Independent determinants of mortality were an older age, the presence of symptoms, and a lower ejection fraction. Patients who were even transiently in New York Heart Association functional class III or IV had a high mortality rate (34 percent yearly), but the rate was also notable (4.1 percent yearly) among those in class I or II. At 10 years, the mean (+/- SE) rates of heart failure, atrial fibrillation, and death or surgery were 63 +/- 8, 30 +/- 12, and 90 +/- 3 percent, respectively. In a multivariate analysis, surgical correction of mitral regurgitation (performed in 143 patients) was associated with a reduced mortality rate (hazard ratio, 0.29; 95 percent confidence interval, 0.15 to 0.56; P<0.001).

CONCLUSIONS

When treated medically, mitral regurgitation due to flail leaflet is associated with excess mortality and high morbidity. Surgery is almost unavoidable within 10 years after the diagnosis and appears to be associated with an improved prognosis; this finding suggests that surgery should be considered early in the course of the disease.

Biplane transesophageal color-flow Doppler imaging in assessing severity of mitral regurgitation: influence of hemodynamic circumstances and mechanism of regurgitation

OBJECTIVE

To determine the value of biplane transesophageal echocardiography in the assessment of severity of mitral regurgitation compared with left ventricular angiography.

DESIGN

Prospective study of consecutive patients.

SETTING

Two university hospitals, one community hospital.

PARTICIPANTS

Thirty-seven patients with angiographically proven mitral regurgitation.

INTERVENTION

Transthoracic and biplane transesophageal echocardiography. In 19 patients, transesophageal echocardiography was performed during general anesthesia.

MEASUREMENTS AND MAIN RESULTS

The largest mitral regurgitation jet area and longest jet as obtained with Doppler color-flow mapping from transthoracic and biplane transesophageal echocardiography and pulsed-Doppler pulmonary venous flow characteristics. Sensitivity and 100-minus-specificity were plotted to constitute receiver operating characteristics (ROC) curves. Areas under ROC curve for transverse, longitudinal, and biplane jet area were 0.77, 0.75, and 0.81, and for jet length, 0.82, 0.84, and 0.88, respectively; this was for biplane jet area in conscious patients; 0.99 compared with 0.72 in anesthetized patients (p < 0.05).

CONCLUSIONS

Biplane measurements identified severe mitral regurgitation slightly more reliably than the transverse or longitudinal measurements alone. In conscious patients, jet area was an excellent test for estimating severity of mitral regurgitation. In anesthetized patients, a combination of biplane jet area and length and of systolic pulmonary venous flow reversal accurately predicted angiographic severity of mitral regurgitation. In anesthetized patients, the optimal cut-off value for jet area to distinguish between moderate and severe mitral regurgitation was lower than in conscious patients. In the total population, regardless of hemodynamic and technical variations, a combination of biplane jet area and length and of systolic pulmonary venous flow reversal accurately predicted the severity of mitral regurgitation.

On Line Echocardiography in Evaluating Left Atrial Changes in Acute Mitral Regurgitation and in Monitoring a Catheter-Mounted Balloon for its Correction

The purpose of this study was to evaluate changes in the left atrial size in acute mitral regurgitation (AMR) and monitor its correction by a catheter-mounted balloon (B). In 16 dogs, pressure changes in the left atrium (LA) were related to LA size and regurgitant mitral flow after the production of AMR by severing the mitral cusps. TEE was used for evaluating LA area (ALA) and the mitral regurgitation flow area (AMRF). TEE was also used in monitoring the position of a catheter-mounted B inserted through the LV apex and positioned on the mitral ring to relieve AMR. The B was inflated during systole and deflated during diastole. The ALA increased by 4.89 ± 1.21 cm2 (mean ± 1 SD) (p < 0.001) after AMR, the AMRF increased by 3.01 ± 0.85 cm2 (p < 0.001) and the mean atrial pressure (LAP) by 9.38 ± 2.43 mmHg (p < 0.001). In all experiments the position of the B could be confirmed in the 2D image and in 4 the reduction of AMRF by the function of the B was documented by the colour flow Doppler. It is concluded that after AMR the size of the LA increases along with the increase in LA pressure and a phasically inflated balloon and its effect on AMR can be easily identified and monitored by TEE.

Left atrial-volume determination by echocardiography. Validation by biplane angiography in the setting of mitral balloon valvuloplasty

To validate echocardiographic left atrial volume measurements, 25 patients with mitral stenosis were studied before and after mitral balloon valvuloplasty. Seven normals served as controls. The modified Simpson's rule was used for echocardiographic and angiographic left atrial volume determination from two orthogonal planes. Left atrial antero-posterior diameter was measured from parasternal long axis view and supero-inferior and medio-lateral diameters from apical four-chamber view. Transthoracic echocardiographic left atrial volume correlated well, but systematically underestimated angiographic left atrial volume (y = 0.4x + 27, r = 0.92). Monoplane transesophageal echocardiography did not improve correlation, nor the underestimation. Out of the several left atrial diameters, antero-posterior dimension showed the closest correlation with angiographic volume (r = 0.91), which persisted after exclusion of patients with atria > 400 ml (r = 0.84). Furthermore, relative changes of antero-posterior diameter after mitral valvuloplasty were closely related to the relative changes observed in left atrial volume (r = 0.82). Our results suggest that, in spite of a consistent underestimation, bidimensional, transthoracic echocardiographic and angiographic left atrial assessment correlate closely. Moreover, it is suggested that the mere antero-posterior diameter from transthoracic two-dimensional image is sufficient in clinical practice for routine follow-op of left atrial volume.

Prediction of outcome after valve replacement for rheumatic mitral regurgitation in the era of chordal preservation

BACKGROUND

Noninvasive predictors of important outcomes after valve replacement for mitral regurgitation have not been examined in a rheumatic population (in whom the results of valve repair are suboptimal) in the era of chordal preservation. Timing of valve replacement thus remains a difficult question in rheumatic mitral regurgitation.

METHODS AND RESULTS

Of 278 patients followed after valve replacement, 66 had pure or predominant mitral regurgitation, and in 61 of these the etiology was rheumatic. The mean age was 24 years. After a mean follow-up of 24 +/- 10 months, the ability of preoperative clinical and echocardiographic data to predict outcome was assessed prospectively, and the possible impact of chordal preservation (n = 35) on survival and post-operative left ventricular function was examined retrospectively. There were no perioperative deaths. There were six postoperative deaths, all the result of heart failure and all related to left ventricular dysfunction. The mean probability of survival was .90 at 16 months. In a stepwise Cox proportional hazards regression analysis, the only independent predictor of postoperative death was preoperative end-systolic diameter. According to a logistic model, the probabilities of death (n = 6) and death or severe heart failure (n = 7) increased abruptly at a preoperative end-systolic diameter of 51 mm (probabilities, .23 and .31, respectively), and the accuracy of this cut point for predicting outcomes was 97% and 98%, respectively. Multiple linear regression analysis identified a large preoperative end-systolic diameter and the need to use tricuspid annuloplasty as significant independent predictors of postoperative fractional shortening; the use of chordal preservation (n = 35) was not a predictor of postoperative fractional shortening. A good outcome was predicted at a preoperative end-systolic diameter of 40 mm: probability of death or heart failure was .0001, and predicted mean postoperative fractional shortening was 0.27 after mitral valve replacement without tricuspid annuloplasty.

CONCLUSIONS

When preoperative end-systolic diameter is more than 50 mm, a poor postoperative outcome is predicted despite chordal preservation in relatively young patients with rheumatic mitral regurgitation, and alternative strategies should therefore be considered. When preoperative end-systolic diameter is 40 mm or less, an excellent outcome is predicted, and close observation without surgery would appear to be reasonable in the absence of symptoms.