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The
Answer is 3
Unlike other
valvular lesions,chronic asymptomatic severe MR is a deceptive lesion
for both the patient and the physician. Management is far more difficult
than any other valvular lesion and the following facts should be remembered
when patients with chronic severe organic MR are encountered.
1.Surgery
is always the definitive treatment modality for severe MR.
2.There is
no controlled trials comparing the effect of medical treatment versus
surgical therapy in patients who have severe chronic asymptomatic MR.Designing
such trials are difficult since MR is a heterogeneous disease in terms
of severity and etiology.Medications (ACEI or beta blocker) do not pose
survival benefit in these patients.Though ACEI can be prescribed in patients
with left ventricular dysfunction,the teratogenic side effects must be
explained and documented to all female patients of child bearing age for
medico-legal purpose.
3.Organic
severe MR is not a benign disease.Excessive mortality and morbidity (atrial
fibrillation,heart failure)is noted and surgery is nearly unavoidable
during long term follow up.No group at very low risk under medical treatment
can be defined (NEJM 1996; 335:1417-23)
4.Sudden death
is a catastrophic event,responsible for about a quarter of the deaths
occurring under medical treatment (JACC 1999; 34: 2078-85)
5.MR is a
progressive disease.However the rate of progression is not uniform and
is unpredictable (JACC 1999; 34:1137-44)
6.Infective
endocarditis is a serious complication which can cause rapid downhill
course.Remember to educate your patient the importance of antibiotic cover
during invasive procedures.
7.MR causes
increase in preload &decrease in afterload, therefore LV function
often looks better than true myocardial function.Postoperatively EF immediately
decreases by approximately 10%with increase in afterload.
8.Survival
after mitral valve repair is always better than mitral valve replacement
if feasible (Circulation 1995; 91: 1022-1028)
9.Significant
calcification,rheumatic etiology,or endocarditis are factors unfavorable
for mitral valve repair.Posterior mitral valve leaflet prolapse is always
easier to be repaired than anterior or bileaflet mitral valve prolapse.
10.CXR monitoring
of cardiothoracic ratio is not reliable to guide the presence or absence
of LV dysfunction.
11.Two main
echocardiographic parameters to consider mitral valve surgery in the absence
of cardiac symptoms are:(1) evidence of LV dysfunction with LV end systolic
dimension >= 40mm (normal <36mm)and / or LVEF <= 60%(normal >
60%)(2)pulmonary hypertension with resting pulmonary artery systolic pressure
>50mmHg (normal around 30-35mmHg).
12.Due to
smaller body built of Chinese population comparing with Caucasians,we
usually advocate 40mm and not 45mm as the cutoff line for surgical referral.
13.If the
valve can be repaired with low operative risk (<=1%), development of
paroxysmal AF,massive degree of MR (regurgitant volume >100ml),severe
left atrial dilatation (M mode dimension >45mm),abnormal EF response
to exercise can also be indications to consider valvular surgery.
14.Symptoms
of the patient always override echocardiographic parameters in decision
for surgery.If a patient has functional class deterioration or unexplained
heart failure,surgery should be advised even in the absence of LV dysfunction
or pulmonary hypertension by echocardiography.Similarly if a patient has
impaired LV function during heart failure hospitalization but recovers
fully during follow up echo,he or she should be referred for early surgery.The
※normal § LV size and function is just a delusion and these patients frequently
suffer from post-operative LV dysfunction.
15.Although
regurgitant lesions are better tolerated than stenotic valvular lesions
during pregnancy,presence of preexisting LV dysfunction poses extremely
high risk for maternal heart failure and death during pregnancy. Therefore
it should be avoided.The valve should be repaired or replaced with bioprosthesis
before pregnancy. If the patient intends for pregnancy after cardiac surgery,
mechanical valve replacement should be avoided due to the need for warfarin
postoperatively.
In summary,chronic
severe organic MR is not a benign disease. If the golden time for surgery
has passed,the patient will suffer from irreversible LV dysfunction despite
corrective mitral valve surgery.Early LV dysfunction and pulmonary hypertension
are the two main indications for early surgery in the absence of cardiac
symptoms which can be determined accurately by echocardiography.The role
of ACEI or beta blocker in severe MR remains undetermined.
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