Fatigue in a Woman With a Heart Murmur

A 59-year-old woman comes to your office for evaluation of her heart murmur.During the last several months, she has tired more easily and has had less energy.Recreational activities, such as lap swimming, have become difficult becauseshe is easily winded. She denies chest pain, foot swelling, and nocturnal dyspnea.

HISTORY
The patient had rheumatic fever at age 10 and has had a loud heart murmurever since. She had no cardiac complications during her 3 pregnancies.Prophylactic antibiotic and warfarin therapy have been effective; she has neverhad endocarditis, thromboembolism, or bleeding. She has had yearly examinations,including echocardiograms that have always shown her heart function tobe "better than normal."

PHYSICAL EXAMINATION
The patient appears well and is afebrile. Heart rate is 84 beats per minuteand blood pressure, 138/82 mm Hg. No conjunctival petechiae, obvious inflammationof the pharynx, or neck vein distention is noted. Chest is clear. Thepoint of maximal impulse is slightly displaced laterally and prominent. Rhythmis regular, with a loud, crisp S1 and normal S2; no S3 gallop is heard, but agrade 3 holosystolic blowing murmur is detected at the apex, with radiation tothe axillae. No diastolic murmurs are discerned. No pedal edema or splinternail hemorrhages are present.

LABORATORY ANDIMAGING RESULTS
The hemogram and chemistry panel are normal. INR is 3. A chest radiographshows a prominent left ventricle (LV) but no evidence of congestiveheart failure (CHF). An echocardiogram reveals a thickened LV with an endsystolicdimension of 45 mm and an ejection fraction (EF) of 55%; moderatemitral regurgitation (MR); and a very small mitral stenosis gradient.

Which of the following is the most appropriate next step?A. Refer the patient to a cardiac surgeon for mitral valve repair if possible
and valve replacement if needed.
B. Monitor echocardiographically at more frequent intervals (every6 months); refer to a cardiac surgeon when EF falls below 30%.
C. Initiate vasodilator therapy.
D. Initiate parenteral antibiotics for treatment of atypical endocarditis,and order a transesophageal echocardiogram (TEE).

CORRECT ANSWER: A
This patient has both clinical and echocardiographic evidenceof chronic MR. More than half the cases of MRseen in surgical series in the United States are the resultof mitral valve prolapse; rheumatic valve disease and endocarditisare less common causes.¹

In this patient, MR stems from rheumatic fever duringchildhood. She exhibits the typical holosystolic apicalheart murmur that radiates to the axillae. The echocardiogramconfirms that MR is the cause of the murmur.

Interpreting the echocardiographic evidence. Thepatient has been followed up carefully with yearly echocardiograms-probably because of the impressiveness of hermurmur. Echocardiography reveals 2 findings that suggestfurther intervention is now indicated.

First, although her EF had been greater than normalfor many years, it is now only normal. The loading conditionsin compensated MR favor LV ejection: they increasepreload and often decrease afterload. This markedly enhancesLV emptying, which results in greater than normalEF values-frequently 70% or more. Thus, normalizationof the EF implies a decrease in muscle function, whichhas been linked to poor outcomes.

Second, the end-systolic dimension of the LV has increased.The ability of the LV muscle to contract is measuredechocardiographically by the end-systolic dimension.Studies have shown that morbidity and mortality areincreased with dimensions of 45 mm or greater.² Thus,this patient displays the 2 echocardiographic findings thatare cause for concern in those with MR: normalization ofEF and end-systolic LV dimension of at least 45 mm.

Significance of the clinical evidence. Although theechocardiographic findings alone would be reason to evaluatethe patient for surgery, the worsening of CHF symptomsis another, independent mortality risk factor that warrantsconsideration of surgical repair. Thus, there are both clinicaland echocardiographic grounds for surgery (choice A).

In patients with MR, repair of the valve is preferableto replacement. The superiority of repair reflects the importanceof the mitral valve apparatus (chordae tendineaeand papillary muscles) to proper postoperative LV functionand EF.³

More frequent echocardiographic monitoring and referralfor surgery when the EF falls below 30% (choice B)is far too conservative an approach; moreover, it exposesthe patient to markedly increased surgical and overallmortality. In patients whose mitral valve is repairable, anEF of 60% or less is a criterion for repair. However, even ifthe valve is not repairable (as can occur in patients with ahistory of rheumatic fever), the likely outcome of surgerybecomes prohibitively poor once the EF reaches 30% orless. The object of following patients with MR carefully isto enable intervention before serious, irreversible LV dysfunctionoccurs.

Studies of various medical therapies for MR havebeen disappointing. No medical therapies-including vasodilators(choice C) that reduce afterload and, thus, theoreticallyfacilitate LV emptying and improve EF-havebeen shown to reduce the need for surgery, permit postponementof surgery, or improve overall outcome.⁴

Finally, although this patient has a history ofrheumatic fever and is at risk for endocarditis, she hasbeen diligent in complying with prophylaxis. She has nosymptoms or physical stigmata of endocarditis, and theechocardiogram does not show vegetation on the valve.Although a TEE (choice D) might reveal vegetations overlookedon a standard echocardiogram, the clinical evidencepoints to MR as the cause of her symptoms. Thus,there is little need for a TEE.

References:

REFERENCES:

1.

Olson LJ, Subramanian R, Acherman DM, et al. Surgical pathology of the mitralvalve: study of 712 cases spanning 21 years. Mayo Clin Proc. 1987;62:22-34.

2.

Carabello BA, Crawford FA. Valvular heart disease. N Engl J Med. 1997;337:32-40.

3.

Otto CM. Evaluation and management of chronic mitral regurgitation. N EnglJ Med. 2001;345:740-746.

4.

Bonow RO, Carabello BA, de Leon AC Jr, et al. ACC/AHA guidelines for themanagement of patients with valvular heart disease: a report of the AmericanCollege of Cardiology/American Heart Association Task Force on PracticeGuidelines. J Am Coll Cardiol. 1998;32:1486-1588.