Left Ventricular & Atrial Reverse Remodeling

MRI to Evaluate Left Ventricular and Left Atrial Reverse Remodeling after Restrictive Mitral Valve Repair

Jos J.M. Westenberg, Ph.D.

Introduction

The effect on left ventricle (LV) and left atrium (LA) remodeling is unknown for patients who underwent successful mitral valve (MV) repair with a restrictive annulusring.

Methods

Twenty patients with dilated cardiomyopathy, LV dysfunction (ejection fraction 36±11%) and severe mitral regurgitation (grade 3-4+), underwent restrictive mitral annuloplasty. A patient example is presented in movie1. The mitral regurgitation can be depicted from the flow going from the LV into the LA during systole. Serial MRI studies were performed (within one week pre-surgery, and two months (n=18) and one year (n=13) post-surgery). End-diastolic (EDV) and end-systolic volumes (ESV) were obtained both for the LV (from short-axis MRI) as well as the LA (from biplane area-length with orthogonal long-axis 2-chamber and 4-chamber view). Aortic flow measurements were obtained from velocity-encoded MRI, to determine the true stroke volume (SV). The ejection fraction (EF) was obtained from SV/EDV. LV measurements (EDV, ESV, LVEF, LV mass) from short-axis are reported to be reproducible. The reproducibility of LA volume measurements with biplane area-length in long-axis MR images was studied by Sievers et al (J Cardiovasc Magn Reson. 2004;6:855-863). Intra- and inter-observer variations of our image analysis were determined by repeated analysis by one observer (blinded to the first analysis with an interval >1 month) and additional image analysis of a second observer (blinded to the results from the first observer).

Results

Early mortality was 10% (n=2); all surviving patients were free from endocarditis and thrombo-embolism. NYHA class improved from 3.2±0.4 to 1.2±0.9. Only 1 patient developed recurrent severe mitral regurgitation during follow-up and was re-repaired. An example is presented in Figure 1. In the panels above, the four-chamber during end-diastole and end-systole pre-surgery are presented. In the panels below, the four-chamber at two-months follow-up is presented. LV and LA reverse remodeling can be depicted visually. The restrictive MV annulus ring can be depicted by the area of signal loss in the MR image, caused by the susceptibility artifacts in the paramagnetic material of the ring. All MRI results are summarized in Table 1. LAEDV decreased significantly from 92±32 ml to 71±22 ml (p=0.01) and remaining on 75±17 ml (p=0.46). On a patient-basis, 50% of patients exhibited significant LA reverse remodeling (predefined by a reduction ?15% in volume) for EDV, with 44% of the patients showing early reverse remodeling and 6% showing late reverse remodeling. LAESV decreased significantly from 165±48 ml to 109±23 ml (p<0.01) and remaining on 111±28 ml, (p=0.81). On a patient-basis, significant LA reverse remodeling (predefined by a reduction ?15% in volume) for ESV occurred in 78% of the patients, with 72% showing early reverse remodeling and 6% showing late reverse remodeling. LVEDV decreased significantly from 244±56 ml to 184±54 ml (p<0.01) and increased insignificantly to 195±67 ml, (p=0.58). Significant reverse remodeling of EDV occurred in the majority of patients (67%) at early follow-up, whereas 11% exhibited reverse remodeling only at late follow-up. In the entire group, LVESV did not change significantly at early or late follow-up (94±39 ml vs. 88±55 ml (p=0.50) vs. 96±72 ml (p=0.28)), but on a patient-basis, 50% showed significant reverse remodeling of ESV at early (44%) or late (6%) follow-up. Intra- and inter-observer variations of LAEDV and LAESV measurements were determined by repeated analysis by the same observer and one additional observer. The results are presented in Table 2. The coefficient of variation (defined as the standard deviation of the differences between the two series of measurements divided by the mean of both measurements) never exceeded 5%, for both intra- as well as inter-observer variation.

Table 1. MRI results: pre-surgery, two months and one year follow-up.

pre-surgery

p

2-month FU

p

1-year FU

LAESV (ml)

165±48

<0.01

109±23

0.81

111±28

LAEDV (ml)

92±32

0.01

71±22

0.46

75±17

LVESV (ml)

94±39

0.50

88±55

0.28

96±70

LVEDV (ml)

244±56

<0.01

184±54

0.58

195±67

LVEF (%)

35±8

<0.01

46±13

0.26

46±15

LV Mass (g)

150±43

0.02

132±39

0.15

136±33

LA: left atrium; LV : left ventricle; ESV: end-systolic volume, EDV: end-diastolic volume; EF: ejection fraction.

Table 2. Intra- and inter-observer variation study of ED and ES volume measurements of left atrium with biplane area-length.

EDV
intra-observer

ESV
intra-observer

EDV
inter-observer

ESV
inter-observer

coefficient of variation

4%

5%

5%

5%

confidence interval

-8 ml - 12 ml

-18 ml - 24 ml

-6 ml - 14 ml

-12 ml - 25 ml

p-value

0.76

0.35

0.06

0.14

EDV: end-diastolic volume; ESV: end-systolic volume

Overall, 78% of the patients showed early or late LA reverse remodeling as well as 78% of the patients showed early or late LV reverse remodeling. Only one patient (6%) did not show any (early or late) reverse remodeling. The volume data are presented in Figure 2. LVEF increased significantly over time: from 35±8% at baseline to 46±13% (p<0.01) at early follow-up and remained on 46±15% at late follow-up (p=0.26). Of note, 72% of patients showed a significant increase in LVEF (predefined as an increase in LVEF ?5%) at early follow-up, whereas 6% only showed an increase at late follow-up. One patient showed recurrent mitral regurgitation and was in NYHA class III at late follow-up; this patient showed a decrease in LVEF from 12% at baseline to 7% at one year follow-up. LV mass showed a statistically early significant decrease (predefined by a reduction ?10 g): from 150±43 g to 132±39 g (p=0.02) and remaining on 136±33 g (p=0.15). In addition, 67% of the patients showed a significant decrease in LV mass at early follow-up, whereas 6% showed a significant decrease at late follow-up.

Figure 1
Figure 1.

Figure 2
Figure 2.

Movie 1
Movie 1.

Conclusion

MRI showed significant LA and LV reverse remodeling in patients with non-ischemic dilated cardiomyopathy and severe mitral regurgitation who underwent restrictive mitral annuloplasty. In particular, 78% of patients showed reverse remodeling of the LA and LV. Moreover, LVEF improved significantly in 78% of the patients with a reduction in LV mass in 72%. The intra- and inter-observer variations for the data analysis of the current study are very low (i.e. not exceeding 5% in volume measurements). The criterion used for reverse remodeling definition (i.e., volume increase ?15%) amply exceeds the observer variations. MRI has a superior image quality as compared to echocardiography and is not hampered by technical limitations such as suboptimal acoustic windows. MRI has the advantage of acquiring every arbitrary double-obliquely-oriented imaging plane in 3D. MRI is currently considered the gold standard for assessment of LA and LV volumes, and its non-invasive character and high reproducibility make this technique ideal for follow-up studies after therapy.

Publications

Westenberg JJM, van der Geest RJ, Versteegh MIM, Lamb HJ, Braun J, Doornbos J, de Roos A, van der Wall EE, Dion RAE, Reiber JHC, Bax JJ. MRI to evaluate left atrial and ventricular reverse remodeling after restrictive mitral valve repair in dilated cardiomyopathy. Circulation, 2005; 112[suppl I]: I-437-I-42.

Abstracts

Westenberg JJM, van der Geest RJ, Doornbos J, Versteegh MIM, Lamb HJ, Dion RAE, de Roos A, van der Wall EE, Reiber JHC, Bax JJ. MRI to evaluate left atrial and ventricular reverse remodeling after successful mitral valve repair in ischemic/dilated cardiomyopathy. American Heart Association Scientific Meeting, New Orleans , LA , November 7-10, 2004 (poster). In: Circulation 110 (17): 589-589 2738 Suppl. S.

Contact

Jos J.M. Westenberg, Ph.D.
Division of Image Processing
Department of Radiology, 1-C2S
Leiden University Medical Center
P.O. Box 9600
2300 RC Leiden
The Netherlands
Tel. +31 (0)71 526 4846
Fax. +31 (0)71 526 6801
e-mail: J.J.M.Westenberg@lumc.nl