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J Am Coll Cardiol, 2003; 42:458-463, doi:10.1016/S0735-1097(03)00649-1 © 2003 by the American College of Cardiology Foundation |

* Department of Cardiology, Sakakibara Heart Institute, Tokyo, Japan
Department of Cardiovascular Surgery, Sakakibara Heart Institute, Tokyo, JapanFinancial support was given by the Japan Research Promotion Society for Cardiovascular Diseases.
Manuscript received October 28, 2002; revised manuscript received February 24, 2003, accepted March 7, 2003.
* Reprint requests and correspondence: Dr. Eiji Ohtaki, Department of Cardiology, Sakakibara Heart Institute, 2-5-4, Yoyogi, Shibuya-ku, Tokyo 151-0053, Japan.
eohtaki{at}shi.heart.or.jp
| Abstract |
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BACKGROUND: Some reports have shown that the preoperative echocardiographic data of left ventricular ejection fraction (LVEF) and left ventricular end-systolic diameter (LVDs) were good predictors of postoperative LV dysfunction. However, few reports were based on long-term follow-up data of large numbers of patients who underwent MVR in the last decade.
METHODS: A total of 274 patients with moderate or severe MR underwent MVR between October 1, 1991, and September 30, 2000. Among them, 171 patients who had both an operation for isolated MR due to degenerative pathology and a postoperative echocardiogram were studied. Postoperative echocardiograms were performed 3.9 ± 2.4 years after the operation.
RESULTS: The LVEF decreased from 66 ± 10% before surgery to 63 ± 11% after surgery (p < 0.0001). On univariate analysis, preoperative LVEF and LVDs correlated with postoperative LVEF (r = 0.41 and r = 0.39, respectively). Overall, postoperative LV dysfunction (defined as LVEF <50%) was not frequent (12%). However, the incidence of postoperative LV dysfunction was high in patients with preoperative LVEF <55% (38%) or LVDs
40 mm (23%).
CONCLUSIONS: In patients with MR, the echocardiographic data of LVEF and LVDs were good predictors of postoperative LV dysfunction. When a decrease in LVEF or an increase in LVDs is detected, MVR should be considered to preserve postoperative LV function.
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Some reports have shown that preoperative echocardiographic data, especially left ventricular ejection fraction (LVEF) and left ventricular end-systolic diameter (LVDs), were good predictors of survival (1214) and postoperative LV dysfunction (3,5,12,13,15) and useful in clinical decision-making on the timing of surgery. Some previous reviews (6,8) and the American College of Cardiology/American Heart Association (ACC/AHA) guidelines (7) recommend MVR even without symptoms if the LVEF falls to lower than 60% or LVDs increases to over 45 mm.
However, few reports on this issue were based on long-term follow-up data of large series of MVR alone (excluding valve replacement) conducted in the last decade. The purpose of this study was to determine whether echocardiographic measures were predictive of LV dysfunction after MVR and useful in deciding the optimal timing of repair, by analyzing a large series of patients who had the operation in the 1990s, with relatively long-term follow-up data.
| Methods |
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Among the remaining 201 patients, 9 (4%) were confirmed to be unsuitable for MVR intraoperatively and converted to mitral valve replacement during the same operation. First, the other 192 patients comprised our study population for patient survival and reoperations. After excluding those without postoperative echocardiographic data at least six months after operation, 171 patients were included in the analysis of postoperative LV dysfunction.
The mean age of the patients was 54 ± 13 years (range 22 to 77 years ), and 107 (63%) were men. Before surgery, 43 patients were in New York Heart Association (NYHA) functional class I, 84 patients were in class II, 40 were in class III, and 4 were in class IV. Among 21 patients without echocardiographic data at least six months after the operation, the mean age was higher (64 ± 9 years, p = 0.001), and 9 (43%) were men. There was no significant difference in preoperative LVEF between patients with and without follow-up echocardiographic data (66 ± 10% vs. 62 ± 12%, p = 0.07).
Surgical procedures. Prolapse of the posterior leaflet was repaired with sliding plasty or resection/suture in most cases, and some required chordal replacement with expanded polytetrafluoroethylene (ePTFE) sutures. Most cases of prolapse of the anterior leaflet were managed with ePTFE sutures (16). The majority of patients also had a ring annuloplasty. Since February 1996, we have been performing physiologic remodeling annuloplasty, which we developed to retain the shape of the anterior leaflet (17). Since 1993, intraoperative transesophageal echocardiography has been routinely performed, and repair was redone when more than mild regurgitation was detected.
Echocardiographic examinations. Postoperative echocardiographic examinations were performed during a follow-up period of 3.9 ± 2.4 years after the operation. For those patients who died or underwent reoperation during the follow-up period, the latest echocardiographic data before death or the secondary surgical intervention was used. The LVEF was calculated by the Teichholz formula from M-mode recordings (18).
Statistical analysis. All data are expressed as means ± SD. A comparison of variables between patients with and without follow-up echocardiographic data and variables before and after MVR was performed by the Student paired t test. The survival rate and survival free of reoperation were estimated by the Kaplan-Meier method. Simple linear regression analysis was used to determine the relationship between preoperative clinical or echocardiographic variables and postoperative LVEF. Stepwise selection multiple regression analysis was used to study multivariate models to predict a postoperative LVEF with significant univariate predictors, with the criterion for inclusion being p < 0.20. The Mann-Whitney U test was used to compare the incidence of LV dysfunction according to more than two classes of preoperative variables. The difference in the incidence between two groups was evaluated using the Fisher exact test. Logistic regression analysis was used to predict postoperative LV dysfunction with preoperative echocardiographic variables. All comparisons were two-tailed.
| Results |
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Comparison of preoperative and postoperative echocardiographic variables. After MVR, both LVDd and LVDs decreased significantly (Table 2). The decrease was much greater for LVDd than for LVDs; thus, the LVEF also decreased significantly from 66 ± 10% to 63 ± 11% (p < 0.0001).
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where "post" and "pre" represent "postoperative" and "preoperative," respectively.
Although univariate analysis showed that preoperative LVDs was more predictive than preoperative LVDd, the model with preoperative LVEF and LVDd had a little higher coefficient of determination than the model with preoperative LVEF and LVDs. This is mainly because a higher correlation coefficient between preoperative LVEF and LVDs (r = 0.81) reduces the additional predictive value of LVDs in relation to LVEF, and this does not necessarily mean that LVDd is a better predictor than LVDs.
Incidence of postoperative LV dysfunction. The overall postoperative LV dysfunction (defined as LVEF <50%) was not frequent (12%). However, among patients with a low LVEF before surgery, the incidence of postoperative LV dysfunction was higher (p = 0.0013, Table 4). Similarly, those with a larger LVDs before surgery had a tendency to have LV dysfunction after surgery (p = 0.006, Table 5).
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40 mm before surgery had a higher risk of LV dysfunction after surgery (p = 0.0007 or p = 0.0019, respectively). Even with a preoperative LVEF
55%, 14% of patients had postoperative LV dysfunction when their preoperative LVDs was 40 mm or above, although logistic regression analysis showed no significant additional predictive value of preoperative LVDs
40 mm with LVEF <55%, compared with LVEF <55% alone, with a relatively low p value (p = 0.1282).
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| Discussion |
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Previous reports have shown that NYHA classification was a good predictor of postoperative survival (14,19) and myocardial failure (3,5). However, the evaluation is subjective, and many people feel only mildly symptomatic because they limit their own activity unconsciously. Thus, a noninvasive and objective echocardiographic examination, which can be done repeatedly, is needed to guide the optimal timing of surgical intervention. Moreover, to determine the timing, we must take into consideration not only postoperative survival but also the incidence of postoperative LV dysfunction. It may be a matter of controversy whether a patient who has slight LV dysfunction but becomes asymptomatic should be recognized to have a bad clinical outcome. However, we studied objective postoperative echocardiographic data, not subjective postoperative symptoms, as the major measure of outcome.
Enriquez-Sarano et al. (15) studied 162 patients with MVR and 104 patients with mitral valve replacement between 1980 and 1989. They reported that preoperative LVEF and LVDs were independent predictors of postoperative LVEF and that surgical correction should be strongly considered in patients with an LVEF <60% or with an LVEF over 60% and an LVDs approaching 45 mm. In another study of 288 patients with MVR and 288 patients with valve replacement, they concluded that the incidence of congestive heart failure was very high in patients with an LVEF <50% and that the incidence was also increased in patients with an LVEF between 50% and 59% (3). Lee et al. (5) studied 167 patients with MVR and 111 patients with mitral valve replacement between 1987 and 1994 and reported that the risk of postoperative myocardial failure was markedly increased when the preoperative LVEF was <40%. In a study of 61 patients with rheumatic MR who were followed up after mitral valve replacement, Wisenbaugh et al. (13) reported that a good outcome was predicted at a preoperative LVDs of 40 mm. Flemming et al. (20) found in a study of 27 patients that an LVDs over 40 mm might be useful for identifying patients with MR and occult LV dysfunction.
However, among the aforementioned studies that examined whether echocardiographic data were predictive of postoperative LV dysfunction, some were based on series composed entirely (12,13) or partially (3,5,15,20) of mitral valve replacement or patients who had an operation in the 1980s (3,15). Others were based on data with a mean follow-up period less than two years (12,20) or data from a small number of patients (12,13,20). The feature of this study is its longer follow-up data of a larger series of MVR conducted in the 1990s.
In our institute, most patients with degenerative MR who need surgical intervention undergo MVR, even with prolapse of the anterior leaflet. Our series showed excellent mid-term results with a good survival rate and survival free of reoperation after MVR.
In the present study, LVDs decreased significantly after surgery, which would imply increased contractility, decreased afterload, or both. Postoperative afterload usually increases with correction of MR, and decreased LVDs is considered to reflect increased LV contractility. The LVEF decreased significantly after surgery, which is consistent with previous studies (4,15). The decrease must be due mainly to a decrease in preload after surgical correction of MR and does not necessarily indicate true impairment of LV systolic performance.
The overall frequency of postoperative LV dysfunction was relatively low (12%) in our series. This may be the result of advances in surgical techniques and the earlier timing of operations at our institute. However, the patients with a lower LVEF or larger LVDs before surgery tended to have postoperative LV dysfunction. In particular, those with LVEF <55% or LVDs
40 mm before surgery had a significantly higher incidence of LV dysfunction after surgery.
Symptomatic patients refractory to appropriate medical therapy obviously require surgery even when LV function is apparently normal (3,5,6,8,14,18,21). In addition, our study suggests that patients with LVEF <55% or LVDs
40 mm are also candidates for repair, considering the lower operative mortality rate in recent years (4,19,22,23). Furthermore, the advances of transthoracic and transesophageal echocardiography have made it easy to determine the feasibility of valve repair before surgery.
We found that an LVEF of 55% and an LVDs of 40 mm identified Japanese patients with a higher risk of postoperative LV dysfunction, and both values were lower than those recommended in the ACC/AHA guidelines (7). These echocardiographic measures in Japanese patients may not be applied directly to patients in other countries, because the normal size of the heart may be different. Nevertheless, these data collectively confirm that the echocardiographic data on LVEF and LVDs are good predictors of postoperative LV dysfunction and are useful in deciding the optimal timing of MVR.
Study limitations. In this study, we defined LV dysfunction as LVEF <50%, according to Enriquez-Sarano et al. (15). However, postoperative LV performance is not determined by LVEF alone. We studied postoperative LVEF, which was easy to measure, but it is only one aspect of LV performance. We did not take into account the effect of medications that reduce LV contractility and the influence of residual MR.
In addition, we included only those patients with degenerative mitral valve disease. Patients with MR due to rheumatic disease are usually less feasible for MVR and more likely to require conversion to mitral valve replacement intraoperatively, even though MVR is expected preoperatively. Also, their LV performance after valve repair is less known. It is still controversial as to when to recommend surgery for an asymptomatic patient with a rheumatic valve that is expected to be repairable.
Conclusions. Our study of a large series of patients who had an operation in the 1990s, with long-term follow-up data, shows that the echocardiographic parameters of LVEF and LVDs are good predictors of postoperative LV dysfunction and useful as objective markers to decide the timing of surgery. Considering the lower operative mortality rate in recent years, when a slight decrease in LVEF or a slight increase in LVDs is detected on an echocardiogram of a patient with degenerative MR, early surgical intervention with MVR should be considered to preserve LV function after surgery.
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