Serum BType Natriuretic Peptide BNP in Patients with

1
Serum B-Type Natriuretic Peptide (BNP) in
Patients with Chronic Mitral Regurgitation is
not Elevated Micah J. Eimer, Deborah L. Ekery,
Vera H. Rigolin, Robert O. Bonow, William G.
Cotts Northwestern University Medical School,
Chicago, Illinois, United States
   
Base-Line Characteristics of the
Patients Characteristic Mitral
Regurgitation Control (n9) (n5) B-Type
Natriuretic Peptide (pg/ml) 11 7.8 5.7
3.7 Age (yr) 45 17 42 12 Ejection
Fraction () 63 12 66 8 Left Ventricular
Internal Dimension, Diastole (cm) 5.7 .55 4.9
.26 Left Ventricular Internal Dimension,
Systole (cm) 3.5 .71 3.0 .36 Left
Ventricular End Diastolic Volume (ml) 132
42 84 23 Left Ventricular End Systolic
Volume (ml) 53 25 27 5.9 Left Ventricular
Mass Index (g/m2) 109 29 72 15 Posterior
Wall Thickness (cm) 0.91 0.09 0.90
0.14 Septum Thickness (cm) 0.90 0.16 0.86
0.15   all values expressed as mean std dev
p0.05
R E S U L T S
O B J E C T I V E S Management of patients with
chronic mitral regurgitation (MR) is based on
monitoring LV size and function in order to
intervene prior to the development of
irreversible LV dysfunction.   B-Type Natriuretic
Peptide (BNP), a ventricular hormone secreted by
myocytes has been found to be elevated in cases
of ventricular volume overload.    We sought to
determine if the abnormal loading conditions
imposed by mitral regurgitation result in
elevated BNP levels and to correlate BNP with
echocardiographic measurements of LV size, LV
mass and severity of symptoms.
BNP v. Symptoms
A B S T R A C T Background Chronic mitral
regurgitation (MR) imposes a progressive
hemodynamic burden upon the left ventricle (LV).
Management is based on symptoms and LV size and
function. To determine if B-Type natriuretic
peptide (BNP), a hormone secreted by ventricular
myocytes under strain, may be a useful marker of
ventricular deterioration, we measured BNP levels
in patients with chronic MR. Methods We
studied 9 patients with moderate to severe MR and
a range of symptoms (mean age 45 16.6) and five
normal control subjects (mean age 42.2 /- 11.1)
by 2D echocardiography with Doppler. LV ejection
fraction (EF), LV end diastolic volume (EDV), end
systolic volume (ESV), and LV mass index (LVMI)
were measured and severity of MR was assessed
semi-quantitatively using color Doppler.
Patients were excluded if they had any other
valve lesion. BNP levels were measured by the
Shionogi assay. Results Patients and controls
did not differ in age and had similar EF (6312
vs 669, pns). Seven of the 9 patients had
severe MR and 6 had dyspnea, of whom 2 underwent
valve surgery within 6 months. Compared to
controls, the MR patients had significantly
higher LVMI (10930 vs 7215 g/m2, p.02), ESV
(5325 vs 276 ml, p.02) and EDV (13242 vs
8423 ml, p.04). However, there was no
significant difference in serum BNP levels (118
vs 64 pg/ml, p0.20) between the two groups, and
BNP did not relate to severity of MR or to
symptoms. However, BNP did appear to be elevated
in the patient with the worst symptoms and most
depressed LV function. Conclusion These
findings suggest that chronic MR is not
associated with elevated levels of B-Type
natriuretic peptide despite significantly
increased LV mass and volumes, even in patients
with symptoms. The elevated BNP seen in the most
symptomatic patient likely reflects the abnormal
LV function. Therefore, BNP may not be a useful
marker in the management and evaluation of
patients with chronic MR.
Correlation Between Echo Findings and
BNP   Variable Correlation P Value Coefficient  
 Posterior Wall Thickness r0.74 plt0.01 Left
Ventricular Mass Index r0.55 p0.04   Mean End
Systolic Volume r0.56 p0.04    Left Ventricular
Ejection Fraction r0.37 p N.S. Symptom
Score r0.17 p N.S. Left Atrial
Diameter r0.02 p N.S. Spearmans correlation
coefficients
BNP v. LV Mass Index
M E T H O D S Nine outpatients with isolated MR
underwent two dimensional transthoracic
echocardiography with doppler and measurement of
serum BNP levels. LV volumes were determined by
apical four and two chamber views utilizing the
modified Simpsons method.    LV mass was
calculated using the modified method of Devereux
and Reichek.   MR severity was assessed
semi-quantitatively using color
doppler. Symptoms were assessed using a modified
Minnesota Living with Heart Failure
questionnaire.   BNP was measured by Shionogi
assay from frozen venous plasma specimens.   Five
volunteers with normal echocardiograms were used
as controls.
R0.55 p0.04
? MR()
In grateful acknowledgement of philanthropic
support from James T. and Laura C. Rhind through
the Northwestern Memorial Foundation.

• C O N C L U S I O N S
• BNP levels are not significantly elevated in
  patients with MR and preserved systolic function.
• However, BNP may be elevated in patients with MR
  and severe symptoms or abnormal LV function.
• Plasma concentration of BNP correlates
  significantly with LV mass index, posterior wall
  thickness and LV end systolic volume.
•  
• Long-term studies to determine the prognostic
  significance of elevated BNP levels in patients
  with MR are warranted.