Elsevier

American Heart Journal

Volume 157, Issue 4, April 2009, Pages 762.e3-762.e10
American Heart Journal

Clinical Investigation
Congestive Heart Failure
Diastolic dysfunction and left atrial enlargement as contributing factors to functional mitral regurgitation in dilated cardiomyopathy: Data from the Acorn trial

https://doi.org/10.1016/j.ahj.2008.12.018Get rights and content

Background

Functional mitral regurgitation (MR) is commonly seen in dilated cardiomyopathy (DCM), which may result from left ventricular (LV) dilatation and alteration in the geometric relationship of mitral valve apparatus. However, not all patients with DCM show significant MR and left atrial (LA) enlargement. The aim of this study was to assess responsible factors for developing mitral valve regurgitation.

Methods

Of 300 patients enrolled in the Acorn trial, baseline echocardiography studies were available in 288, of whom 144 were excluded because of a variety of reasons. Echocardiographic data were examined for the remaining 144 patients in sinus rhythm with DCM, but without organic mitral valve disease and ischemic heart disease. Mitral regurgitation was assessed by color-flow imaging. All echocardiographic parameters were indexed to body surface area.

Results

Of 144 patients, 87 had MR grade ≥2 (group 1) and 57 had MR grade 0 or +1 (group 2). Group 1 had larger tenting area, tenting height, tethering distance, LA volume index, and mitral annular area than group 2 (all P < .001); LV volume index and ejection fraction were similar between groups. The major determinant of MR severity was tenting area (r = 0.49, P < .001), and this was best related to mitral annular area (r = 0.85, P < .001). Mitral annular area was most strongly associated with LA volume (r = 0.56, P < .001). In addition, LA volume index was highly correlated with LV diastolic dysfunction (r = 0.58, P < .001), both in total and in group 2 only.

Conclusions

For patients with DCM in the Acorn trial, MR severity was associated with LA volume and mitral annular area but not with LV volume. Mitral annular area and LA volume were closely related, even in patients without significant MR. These findings suggest that LA enlargement caused by advanced diastolic dysfunction may contribute to causing significant MR by augmenting mitral annular dilatation in DCM.

Section snippets

Population

Echocardiography Core Laboratory at Mayo Clinic, Rochester, MN, performed comprehensive echocardiographic measurements of all patients enrolled in the Acorn trial at 18 different clinical sites. From the baseline echocardiographic data, we identified eligible patients for this study using the following inclusion criteria: (1) no organic mitral valve disease, (2) no history of ischemic heart disease or myocardial infarction causing ischemic functional MR, and (3) presence of sinus rhythm. Of 300

Baseline clinical characteristics

A total of 144 patients (mean ± SD age 53 ± 13 years, 77 men [53%]) were eligible for this study (Table I). Mean ± SD LV ejection fraction was 26.6% ± 8.2%, and LV end-diastolic volume index was 134 ± 45 mL/m2. The mean ± SD duration of heart failure was 5.2 ± 4.2 years. The etiology of DCM was idiopathic in 96 (66.7%), viral in 15 (10.4%), alcoholic in 4 (2.8%), hypertensive in 12 (8.3%), and miscellaneous in 17 (11.8%).

Eighty-seven patients (60.4%) had MR of ≥grade 2 as group 1, and 57

Discussion

Occurrence of functional MR in patients with LV systolic dysfunction is associated with poor prognosis. Hemodynamically significant MR may cause worsening of symptoms and prognosis. Indeed, in previous studies, MR was associated with increased cardiovascular mortality in unselected patients with systolic dysfunction.1, 2

Patients with DCM who have similar LV size and volume frequently have varying degrees of MR, whereas a correlation between LV size and severity of MR is expected if functional

Conclusions

In the Acorn trial of patients with advanced DCM, 60% had MR of grade 2 or greater. The 2 groups of patients categorized by the severity of MR (grade 0 and +1 or grade ≥2) had significant differences in LA volume index and mitral annular size but not in LV volume index. Mitral annular size and LA volume index were closely related even in patients without significant MR. These findings suggest that increased LA volume index caused by more advanced diastolic dysfunction may be a one of the major

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