CLINICAL STUDIES
Progression of mitral regurgitation
A prospective Doppler echocardiographic study
Maurice Enriquez-Sarano, MD, FACC*,
Arsene-Joseph Basmadjian, MD*,
Andrea Rossi, MD*,
Kent R. Bailey, PhD ,
James B. Seward, MD, FACC* and
A. Jamil Tajik, MD, FACC*
* Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic and Mayo Foundation, Rochester, Minnesota, USA
Section of Biostatistics, Mayo Clinic and Mayo Foundation, Rochester, Minnesota, USA
Manuscript received December 17, 1998;
revised manuscript received April 22, 1999,
accepted June 11, 1999.
Reprint requests and correspondence: Dr. Maurice Enriquez-Sarano, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905
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Abstract
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OBJECTIVES
This study was performed to define the rates and determinants of progression of organic mitral regurgitation (MR).
BACKGROUND
Severe MR has major clinical consequences, but the rates and determinants of progression of the degree of regurgitation are unknown. Quantitative Doppler echocardiographic methods allow the quantitation of regurgitant volume (RVol), regurgitant fraction (RF) and effective regurgitant orifice (ERO) to define progression of MR.
METHODS
In a prospective study of MR progression, 74 patients had two quantitative Doppler echocardiographic examinations of MR (with at least two methods) 561 ± 423 days apart without an intervening event.
RESULTS
Progression of MR was observed, with increase in RVol (77 ± 46 ml vs. 65 ± 40 ml, p < 0.0001), RF (47 ± 16% vs. 43% ± 15%, p < 0.0001), and ERO (50 ± 35 mm2 vs. 41 ± 28 mm2, p < 0.0001). Annual rates (95% confidence interval) were, respectively, 7.4 ml/year (5.1, 9.7), 2.9%/year (1.9, 3.9) and 5.9 mm2/year (3.9, 7.8). However, wide individual variation was observed, and regression and progression of RVol >8 ml was found in 11% and 51%, respectively. In multivariate analysis, independent predictors of progression of RVol were progression of the lesions, particularly a new flail leaflet (p = 0.0003), and progression of mitral annulus diameter (p = 0.0001). Regression of MR was associated with marked changes in afterload, particularly decreased blood pressure (p = 0.008). No significant effect of treatment was detected.
CONCLUSIONS
Organic MR tends to progress over time with increase in volume overload (RVol) due to increase in ERO. Progression of MR is variable and determined by progression of lesions or mitral annulus size. These data should help plan follow up of patients with organic MR and future intervention trials.
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Abbreviations and Acronyms
| | ERO | = effective regurgitant orifice | | LV | = left ventricular | | MR | = mitral regurgitation | | NYHA | = New York Heart Association | | RF | = regurgitant fraction | | RTVI | = regurgitant time velocity integral | | RVol | = regurgitant volume |
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In acquired valvular heart disease, there is a trend for progression of valvular lesions, which in turn leads to worsening hemodynamic consequences and, ultimately, to clinical complications (1). The progression of valvular lesions and their consequences is the rationale for regular monitoring of patients with valvular heart disease (2). In aortic stenosis, progression of the degree of stenosis has been demonstrated mainly with Doppler echocardiography, and its analysis has provided important insight into the pathophysiology and consequences of the disease (3–5).
In mitral regurgitation (MR) due to intrinsic valvular lesions, the degree of regurgitation is an essential determinant of the hemodynamic alterations (6,7) and left ventricular (LV) remodeling (8). It is also a determinant of outcome, and patient subsets with mostly mild regurgitation usually have excellent survival (9), whereas those with mostly severe regurgitation often develop LV dysfunction (10) and congestive heart failure (11), and are affected by excess mortality (12). The frequency of these complications has led to the suggestion that surgical correction of MR should be performed early in the course of the disease (13). However, the approach to management of MR remains controversial (14), mainly because little information is available on the rate and determinants of progression of MR.
Angiographic data have suggested that MR may be a progressive disease (15); however, because of the small but definite risk of catheterization (16), studies are rarely repeated. The limitations of semiquantitative gradation of MR based either on angiography (17) or color flow imaging (18,19) have led frequently to inconsistencies (20) and have hindered the assessment of progression of MR. With the recent development of Doppler echocardiographic, noninvasive quantitative methods of evaluating the degree of MR (21–23), a prospective study of MR assessed using these methods at our institution (8,24,25) was initiated to define quantitatively the degree and progression of MR. Therefore, we analyzed the results of serial quantitative echocardiograms from patients with organic MR, with the hypothesis that the regurgitant volume (RVol) of MR increases progressively over time, and we examined the determinants of the consequences of this progression.
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Methods
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Patients.
Inclusion criteria were patients: 1) with isolated organic MR, as defined by two-dimensional echocardiography; 2) with at least a mild degree of regurgitation at baseline; 3) with quantitation of MR performed by one of the authors and using at least two methods simultaneously; and 4) who agreed to return for follow-up quantitative echocardiography after the initial study.
Exclusion criteria were: 1) associated mitral stenosis; 2) associated aortic valve disease; 3) associated congenital or pericardial disease; 4) MR due to LV dysfunction; 5) acute myocardial infarction; and 6) intervening mitral valve repair or replacement. Patients were not excluded on the basis of change in symptoms or clinical findings, of age, gender or treatment received.
The diagnosis of organic MR was based on the presence of intrinsic mitral valve lesions demonstrated by two-dimensional echocardiography and was easily differentiated from functional MR, in which leaflets are normal and MR is secondary to LV alterations. Mitral lesions were classified as restricted motion (rheumatic or sclerotic) or mitral prolapse. At late follow-up, we also specified those with mitral valve prolapse in whom a new flail leaflet developed.
In addition, two other patient groups were analyzed: 1) 51 patients without regurgitation, of the same age and gender, were included for quality control of the Doppler echocardiographic methods; and 2) 248 patients who underwent a prospective baseline quantitation of MR but did not undergo repeat quantitative echocardiography.
Doppler echocardiographic methods.
A complete two-dimensional Doppler echocardiographic examination was performed. The degree of MR was assessed with at least two of the following three methods, which were averaged.
Quantitative Doppler (21,24)
The mitral and aortic stroke volumes were calculated using the annulus diameter measured by two-dimensional echocardiography and the time velocity integral of pulsed-wave Doppler at the annulus level. The RVol was calculated as the difference between these two stroke volumes and the regurgitant fraction (RF) as the ratio of RVol to mitral stroke volume. The effective regurgitant orifice (ERO) area was calculated as the ratio of RVol to the regurgitant time velocity integral (RTVI) (8).
Quantitative two-dimensional echocardiography (22,24)
The LV end-diastolic and end-systolic volumes were calculated with the biplane method of disks (26). Left ventricular stroke volume was calculated as the difference between end-diastolic and end-systolic volumes. Regurgitant volume was calculated as the difference between LV and aortic stroke volume, RF as the ratio of RVol to LV stroke volume and ERO as ratio of RVol to RTVI (8).
Proximal isovelocity surface area
The proximal isovelocity surface area method (23) analyzed the proximal flow convergence region and calculated the ERO as the ratio of regurgitant flow to regurgitant velocity (25,27). Regurgitant volume was then calculated as the product of ERO by RTVI. Regurgitant fraction was calculated as the ratio of RVol to the sum of RVol and aortic stroke volume.
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Other measurements
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The LV end-systolic wall stress was determined using estimated end-systolic pressure (28) and echocardiographic measurement of LV geometry and wall thickness (29). Left atrial volume was measured with orthogonal apical views using the biplane area-length method (30). Cardiac index was measured using aortic stroke volume. Systolic pulmonary artery pressure was measured using tricuspid regurgitant Doppler signal and estimation of right atrial pressure based on inferior vena cava size and respiratory variation.
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Statistics
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Group data are presented as mean ± standard deviation or percentages. Group comparisons were based on the standard t test, analysis of variance or chi-square, as appropriate. The comparison of initial to late data was performed with the paired t test. The slopes of change over time were calculated as the slope (forced through the origin) of the regression between the changes in RVol, RF and ERO observed between the late and initial studies and the delay between studies. The association between continuous variables was analyzed using linear and nonlinear regression. Patients were classified as showing regression, stability or progression of MR according to the changes in RVol, and the characteristics of these three groups were compared using analysis of variance. Analysis of progression of MR was also stratified according to the lesions observed at baseline or at follow-up examination or according to the treatment received after initial echocardiography, and the effect of these stratifications on progression of MR was analyzed by analysis of variance for repeated measurements. The independent determinants of progression of MR between the two examinations were analyzed using multivariate stepwise linear regression. Entry criterion into the model was for variables with p < 0.10 and statistical significance was for p < 0.05.
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Results
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Baseline characteristics.
Between 1991 and 1998, 74 patients (35% women; mean age, 60 ± 14 years) had quantitative echocardiography performed by one of the authors at baseline and during follow up. The valvular lesions involved restricted motion in 10 patients and valve prolapse in 64. At baseline, LV end-diastolic and end-systolic volumes and ejection fraction were 112 ± 29 ml/m2, 38 ± 14 ml/m2 and 66 ± 7%, respectively, significantly higher than in normal controls (all p < 0.001). The baseline left atrial volume was higher than in normal controls (p < 0.0001), and peripheral vascular resistance was slightly higher (p = 0.06). Conversely, systolic and diastolic blood pressure and end-systolic wall stress were not different from those in normal controls (all p > 0.25). Expectedly, RVol and RF in patients were higher than in normal controls (all p < 0.0001). Of note, in normal controls, these calculated values were very small: 4 ± 3 ml and 4.6 ± 3% for RVol and RF, respectively, by quantitative Doppler and 3.5 ± 3 ml and 4 ± 3% by quantitative two-dimensional echocardiography. Therefore, a change in RVol >8 ml was considered clinically significant for regression or progression of MR.
Progression of MR.
The results of the repeated quantitative assessment of MR are shown in Table 1. The delay between the two examinations was 561 ± 423 days, or on average, 1.5 years. Seven patients (9.5%) returned because of symptomatic progression to New York Heart Association (NYHA) class III or IV and 67 (90.3%) for a follow-up quantitative study, as we had suggested at baseline, despite no or minimal symptoms (NYHA class I or II).
Volume overload, characterized by RVol and RF, progressed significantly; the mean change was 13 ± 20 ml for RVol and 5 ± 9% for RF (Fig. 1 and Table 2). In analyzing for the mechanism of increase of volume overload, no significant change in regurgitant duration or driving force (regurgitant gradient and blood pressure) or end-systolic wall stress was observed (Table 1). Conversely, the severity of the regurgitant lesion increased significantly, with a change of ERO of 8.5 ± 15 mm2 (Fig. 1, Tables 1 and 2). Of note, the changes in jet area, jet-to-left atrial area ratio or E velocity were not significant for diagnosing the progression of MR.
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Figure 1 Regurgitant volume (RVol), regurgitant fraction (RF) and effective orifice area (ERO) measured at baseline (B) and at late (L) quantitative echocardiography.
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The progression of MR was associated with more severe consequences of MR, particularly an increase in LV end-diastolic volume index (p < 0.004) and left atrial volume and a decrease in cardiac index (Table 1). The increase in systolic pulmonary artery pressure and end-systolic volume index (p = 0.31) did not reach statistical significance.
The variation in the changes observed was wide, for example, from –26 to +90 ml for RVol. Regurgitant volume decreased >8 ml in eight patients (11%), changed between –8 and +8 ml in 28 (38%) and increased >8 ml in 38 (51%). Because of these changes, 32 of the 33 patients with initially severe MR (RVol  60 ml [31]) still had severe MR at late follow-up, whereas 12 of the 41 with nonsevere MR initially had severe MR at late follow-up. Similarly, RF and ERO varied from –24% to +38% and from –18 to +75 mm2, respectively. This large variation emphasizes the need to define the determinants of progression and regression of MR.
Determinants of progression of MR.
There was no relationship between baseline characteristics such as age, gender, blood pressure, degree of MR, size of the mitral annulus and LV volumes, end-systolic wall stress and ejection fraction and progression of MR (all p > 0.10). Valvular prolapse was associated with greater progression of RVol (p = 0.002) and ERO (p = 0.0009) than in valvular restricted motion.
The delay between the initial and late examinations was also significantly associated with the change in RVol (r= 0.34, p = 0.003), RF (r = 0.34, p = 0.003) and ERO (r = 0.42, p = 0.0008). The slope of the regression was 7.4 ml/year (95% confidence interval [CI] 5.1, 9.7 ml/year) for RVol, 2.9%/year (95% CI 1.9%, 3.9%/year) for RF and 5.9 mm2/year (95% CI 3.9, 7.8 mm2/year) for ERO (Fig. 2). At follow up, the lesions had progressed in 10 patients, who initially had simple valve prolapse but developed a new flail leaflet. The lesions at follow up were strongly associated with the progression of MR (Fig. 2, Table 2).
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Figure 2 Progression of mitral regurgitation expressed per year in the overall series and in groups of patients with restricted motion (RM), stable mitral valve prolapse (MVP-S) and new flail leaflet (NF). (Top) Regurgitant volume (RVol) change. The mean rates (95% CI) were 7.4 ml/year (5.1, 9.7), 0.9 ml/year (–1.9, 3.7), 5.9 ml/year (3.4, 8.5), 18.4 ml/year (13.8, 23.0), respectively (p = 0.0002 for group differences). (Middle) Regurgitant fraction (RF) change. The mean rates (95% CI) were 2.9% (1.9, 3.9), 0.8%/year (–0.9, 2.6), 2.1%/year (1.0, 3.4), 7.3%/year (5.0, 9.6), respectively (p = 0.0013 for group differences). (Bottom)Effective regurgitant orifice (ERO) change. The mean rates (95% CI) were 5.9 mm2/year (3.9, 7.8), 0.05 mm2/year (–1.7 to 1.8), 6.2 mm2/year (3.8 to 8.7), 10.6 mm2/year (8.1 to 13.0), respectively (p = 0.0002 for group differences).
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In univariate analysis, the progression of RVol between baseline and follow-up examination showed a strong correlation with the change in ERO (r = 0.71, p < 0.0001) and mitral annulus diameter (r = 0.63, p < 0.0001; Fig. 3 ) and a weaker correlation with change in transvalvular gradient (r = 0.24, p = 0.066) and end-systolic wall stress (r = 0.30, p = 0.012). The changes in ejection fraction and heart rate showed no significant correlations with the change in RVol (both p > 0.16). The hemodynamic and morphologic changes observed in patients with regression, stability or progression of MR, using a threshold of variation of RVol >8 ml, are shown in Table 3. The patients with regression of MR were characterized by lack of progression of ERO and mitral annulus and also by a decrease in loading conditions. Those with progression of MR showed progression of annulus and ERO size but little change in loading conditions.
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Figure 3 Correlation between change in mitral annulus diameter and change in regurgitant volume. Solid line = regression line.
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Table 3 Changes Observed With Regression, Stability or Progression of Mitral Regurgitation Using a Threshold of Change >8 ml
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The predictors of RVol and ERO at the latest examination, as determined with multivariate analysis, are presented in Table 4. The initial degree of regurgitation and the progression of the lesion and annulus size were the main predictors of the latest degree of regurgitation. The predictors of late RF were similar to those of RVol.
Effect of treatment.
Because the attending physicians, either outside or at our institution, decided treatment use, some patients received new treatment after the initial examination. In the 22 patients receiving blockers of the renin-angiotensin system compared with the other 52 patients, the delay between the two examinations was not different (520 ± 390 vs. 578 ± 439 days, p = 0.59). With regard to afterload, a modest effect was noted for a decrease in systolic blood pressure (–8 ± 17 vs. 0 ± 13 mm Hg, p = 0.043), end-systolic wall stress (–23 ± 34 vs. +1.2 ± 28 g/cm2, p = 0.003) and peripheral vascular resistance (+7 ± 423 vs. +100 ± 318 dynes·cm–5·s–1, p = 0.31). However, no difference in progression of RVol (+12 ± 22 ml vs. +13 ± 20 ml, p = 0.92), RF (+3.4 ± 10 vs. +5.2 ± 9%, p = 0.45) and ERO (+7 ± 13 vs. +9 ± 16 mm2, p = 0.71) was observed. In multivariate analysis adjusting for the predictors of progression of MR, no effect of treatment was noted (all p > 0.70). However, the patient with the largest decrease of MR received treatment (–26 ml of RVol, –18 mm2 of ERO). Excluding the 22 patients who had new treatment, the rates of progression of MR were similar to that of the overall group (6.8 ml, 2.9% and 6.5 mm2/year for RVol, RF and ERO, respectively).
Methodologic assessment.
Because of the relatively wide range of delay between the initial and late echocardiograms, the analysis was repeated in the patients with delay >180 days (n = 63). The mean change and rate of change per year were similar to those for the overall group, 15 ± 21 and 7.6 ml/year for RVol, 5.5 ± 9% and 2.9%/year for RF and 10 ± 16 mm2 and 5.9 mm2/year for ERO.
The concern that patients returning for repeat echocardiography may be selected was addressed by comparing the baseline characteristics of the present patients with those of 248 patients who had an initial examination during the same period and did not return for repeat quantitative echocardiography. The patients who did not return tended to be slightly older (64 ± 14 years, p = 0.09) and have higher peripheral vascular resistance (1,651 ± 377 dynes·cm–5·s–1, p = 0.07). However, no differences in gender (p = 0.92), LV volumes, ejection fraction, wall stress (all p > 0.14), RVol, RF, ERO (all p > 0.28), left atrial volume (p = 0.40) or systolic and diastolic blood pressure (both p > 0.33) were noted. Therefore, the present group is highly representative of those quantitatively examined for MR.
The techniques used in the present study provided low calculated RVol or RF in patients without regurgitation, as noted above. The degree of regurgitation was determined as the average of 2.6 and 2.9 methods for the initial and late examination, respectively. Furthermore, high correlations were observed between methods (all r > 0.94, all p < 0.0001), with no systematic trend for over- or underestimation (all p > 0.18).
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Discussion
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The present study showed that in organic MR: 1) progression of MR occurs over time, at an average rate of 7.4 ml/year, 2.9%/year and 5.9 mm2/year for RVol, RF and ERO, respectively; 2) marked individual variations of the changes are observed, with notable decrease in 11% of patients, relative stability in 38% and marked increase in 51%; 3) the progression of volume overload occurs mainly through progression of the regurgitant orifice rather than regurgitant gradient; 4) regression of volume overload is associated with regression of loading conditions; and 5) progression of lesions and mitral annular diameter are major independent determinants of the progression of MR.
Progression of MR.
The progression of MR is essential in understanding this disease, because patients with severe MR incur a much higher mortality and morbidity (12) than those with a milder degree of regurgitation (9). Furthermore, the high risk of LV dysfunction in patients with severe regurgitation (10,32,33) has led to the suggestion that surgery should be performed early (13). However, because of the paucity of data available on progression of MR (15), the rates of change in the degree of MR and the underlying mechanisms are not certain. In patients with aortic stenosis, information provided by serial studies has been instrumental in understanding the disease and managing it clinically (3–5). However, such information became available long after the validation of quantitative noninvasive methods for assessing the degree of stenosis (34–36). Similarly, in MR, new methods (21–23) of assessment of the degree of MR and new concepts (8,27) have developed progressively and have been introduced into clinical practice in the last decade. To our knowledge, the present study is the first, using these quantitative methods, to report the progression of MR. An important finding of the present study is that over time MR progresses significantly. This progression, which was suspected clinically (1,2) and supported by limited data (15), was confirmed individually by all methods used. The rate of progression of 7.4 ml/year led to an increase in the prevalence of severe MR from 45% to 59%. This progression is responsible for increasing consequences of MR, with progression of left atrial and LV enlargement and reduction of cardiac index (6,7), emphasizing the importance of defining its patterns and determinants.
Compared with aortic stenosis, in which little regression is observed (3,4), the pattern of change in MR is different, and both progression and regression are observed. This observation is consistent with the nature of mitral lesions, which are rarely fixed and have been shown experimentally (37,38) and clinically (39) to vary with acute interventions. Experimental (40) and clinical (41,42) evidence also suggest that even during the course of systole, the degree of the mitral lesion might vary. Therefore, in contrast to other valvular lesions, the long-term progression observed overall is not homogeneous and notable regression may occur, albeit rarely, in 11% of patients. However, in the majority of patients, MR progresses and the present study allowed several predictors of this progression to be defined.
Determinants of progression of MR.
The area of the regurgitant orifice, the transvalvular gradient and the duration of regurgitation determine the degree of regurgitation. In the present study, the main determinant of progression was an increase in ERO, which occurred by two mechanisms.
First, the valvular lesions at baseline and their progression are major determinants of progression of MR. Hence, more progression occurs in mitral valve prolapse than in nonprolapsing valves (15). However, the most important determinant of marked aggravation of MR is the occurrence of a new flail leaflet. This occurred in 10 of 64 patients (16%) with mitral valve prolapse and was associated with a marked increase in RVol (+36 ml) and ERO (+18 mm2). These data substantiate the major implications of flail mitral leaflets for outcome of patients with MR (12).
Second, increase in annular diameter results in reduced leaflet coaptation. The physical properties of the mitral annulus are not well known (43) and may explain the differences in progression of prolapsing and nonprolapsing valves. A decrease in mitral annular diameter is an essential element in mitral valve repair and prevention of MR (44). Mitral annular enlargement may be induced by LV and atrial enlargement due to MR (8), in turn, inducing additional increase in ERO and RVol and, thus, further ventricular and atrial dilation. This positive feedback loop may lead to massive degrees of chronic MR that can be observed even in asymptomatic patients and would barely be compatible with life if the lesions occurred acutely (8,25,27). Conversely, changes of loading conditions appear to have little bearing on MR progression but seem important in MR regression.
Determinants of regression of MR.
Regression of MR has been observed mostly in acute hemodynamic interventions, essentially in functional and not organic MR (39,45). To our knowledge, long-term regression of MR is demonstrated for the first time in the present study. The mechanism of regression is different from that of progression and involves little change of the ERO and annular diameter. Conversely, major decreases in blood pressure, peripheral vascular resistance and wall stress are the main contributors to a long-term decrease in RVol. It is unclear whether regression of MR is only transient, and assessment of longer-term outcome will require further studies.
Also, the mechanism of MR regression appears to contradict the lack of measurable effect of blockers of the renin-angiotensin system. The effect of this type of treatment remains controversial in MR (46). However, in the present study, the group with regression of MR demonstrated a much greater change in afterload than did the treated group. The causes of the loading changes are unclear, but the data suggest that regression of MR requires intense afterload reduction. Therefore, analyzing the potential of medical treatment to induce regression of MR will require formal trials of high doses of highly potent treatment (46).
Practical implications.
The progression of MR demonstrated in the present study suggests that regular follow-up echocardiographic examinations should be performed in patients with organic MR. The results of the present study suggest that quantitative methods should be the preferred approach for detecting progression of MR, which could not be appropriately diagnosed using color flow imaging or LV filling variables. The progression of MR is poorly predictable using baseline characteristics. The optimal delay for follow-up examination is difficult to determine but should be shorter in valve prolapse and when progression may lead MR to reach severe regurgitation thresholds (31). In our opinion, a reasonable delay is about 1 year for patients in grade III and higher (RVol 45 ml), and longer intervals may be appropriate for patients with smaller degrees of MR. Other factors such as LV function should be considered in the recommendation, and the appropriateness of such recommendations should be tested in large outcome studies.
Study limitations.
A study in which all patients have follow-up echocardiography after a fixed delay would be appealing but has not been achieved. Although selection bias cannot be ruled out, the patients included in the present study showed no significant differences from the other patients in our prospective cohort with MR studied quantitatively. The delay in follow-up studies varied because no specific delay was enforced to avoid the "healthy participant" bias, but it was used in calculation of progression rates and in multivariate analysis defining independent determinants of progression of lesions. Therefore, the potential for selection bias in the present study is limited.
Because the patients were followed by their personal attending physicians, we could not keep all treatment from patients, but the effect of long-term orally administered vasodilators is controversial and uncertain (46). In the present study, no significant effect of the blockers of the renin-angiotensin system was noted, but because of the relationship between amplitude of afterload changes and decrease of MR, prospective trials of high doses of drugs of high potency should be planned.
The correlation between changes in RVol and mitral annulus may be affected by the fact that for quantitative Doppler, mitral annulus is used in the calculation of RVol. However, a similar (r = 0.61, p < 0.0001) correlation was found using RVol calculated by quantitative two-dimensional echocardiography for which no tautological relationship exists.
The value of Doppler echocardiographic methods has been criticized. However, studies from multiple centers have demonstrated that consistent use (24), high-resolution imaging and appropriate ascertainment of flow convergence (25) allow accurate quantitation of MR. Furthermore, we averaged the results of at least two, and usually three, methods to define RVol, RF and ERO. Furthermore, a high consistency was observed among the methods. Also, the results observed in patients without regurgitation support, in our experience, the accuracy of the methods of quantitation of MR, which do not represent a limitation of the study.
The present study is, to our knowledge, the first quantitative report of progression of MR, but larger patient populations will be required in future studies to determine progression in all subsets of patients.
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Conclusions
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In organic MR, progression of MR occurs over time, at an average rate of 7.4 ml/year, 2.9%/year and 5.9 mm2/year for RVol, RF and ERO, respectively. Higher rates of progression are determined by progression of lesions or of mitral annular dilation. Regression of MR is possible with marked afterload reduction. These data should help to plan follow up of patients with organic MR and to plan future intervention trials.
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Footnotes
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This work was supported in part by a grant-in-aid from the American Heart Association, Minnesota Affiliate.
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References
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