Attending Version
Aortic Stenosis Module
Created by Dr. Kye Park
Objectives:
1.
2.
3.
4.
Identify the major causes of aortic stenosis
Understand the underlying pathophysiology of aortic stenosis
Define how aortic stenosis is classified
Know the indications for when surgical valve replacement is warranted
References:
1. Carabello BA. Aortic Stenosis. NEJM 2002;346(9):677-82.
2. Bonow et al. ACC/AHA Practice Guidelines. JACC;2006;48(3):e1-148.
3. Otto et al. Medical Knowledge Self Assessment Program 14 (MKSAP). 2006.
American College of Physicians.
CASE
HPI: 60 year old man comes to your office for routine physical. He has been told that he
has a murmur of some kind by his previous doctor. He walks 5 miles everyday without
any symptoms and his exercise tolerance has not changed in the last few years. He has
not noticed any swelling in his legs, shortness of breath when he lies down.
Past Medical History:
Hypertension
Hyperlipidemia
Abdominal Aortic Aneurysm
Medications:
ASA 81 mg PO daily
Metoprolol 25mg PO daily
Atorvastatin 40mg PO daily
MVI daily
Allergies: none
Family History: brother with heart attack at age 57.
Social History: works as an accountant. Denies smoking, alcohol or illicit drug use.
Physical Exam: Vitals: Tm 99.5, P 80, R 16, BP 154/83 O2 sat 98% on RA
General: comfortable, NAD, A/Ox4
HEENT: PERRL, EOMI
Lungs: CTA bilaterally
CV: RRR, 3/6 late-peaking systolic ejection murmur at 2nd right intercostals space
radiating to the neck. Single S2. No S3 or S4. Carotid upstroke is normal.
Abdomen: soft NTND, normal bowel sounds.
Ext: no clubbing, cyanosis, or edema.
Labs: CBC, Chemistries, LFT’s are within normal limits
ECG: normal
Transthoracic echocardiogram:
Normal systolic function, heavily calcified aortic valve. Peak gradient 64 mm Hg,
Mean gradient of 50 mm Hg. Calculated valve area is 0.7 cm2.
What is the next step in the management of this patient?
This patient has asymptomatic severe aortic stenosis (AS) and therefore does not need
valve replacement. Aortic valve replacement is generally reserved for severe
symptomatic AS, AS associated with decreased EF or in situations where there is a
concurrent need for CABG or other valve replacement. Many would advocate that he
should undergo exercise testing to determine if he is at high enough risk to undergo aortic
valve replacement. If he develops symptoms or has an abnormal blood pressure response
during exercise testing, he may benefit from valve replacement (ACC/AHA class IIb
indication).
Discussion Outline:
1. Pathophysiology of Aortic Stenosis
1. Most common cause of AS in adults is calcification of a normal trileaflet or
congenital bicuspid valve.
2. An active disease process similar to atherosclerosis, characterized by lipid
accumulation, inflammation, and calcification.
3. Over time, left ventricle adapts to systolic pressure overload through hypertrophy.
However, if relative wall thickness does not increase in proportion to pressure,
wall stress increases and the high afterload decreases the ejection fraction.
Depressed myocardium contractility is also thought to play a part in decreased
EF. This eventually leads to systolic/diastolic dysfunction producing symptoms
of congestive heart failure.
2. Symptoms
Classic symptoms include syncope, heart failure and angina. However, most patients
initially present with more subtle symptoms, such as decreased exercise tolerance of
dyspnea on exertion.
3. Disease Classification:
a. Mild: (area 1.5 cm2, mean gradient < 25 mm Hg, or jet velocity < 3.0 m/s)
b. Moderate: (area 1.0 to 1.5 cm2, mean gradient 25 to 40 mm Hg,
or jet velocity < 3.0 to 4.0 m/s)
c. Severe: (area < 1.0 cm2, mean gradient > 40 mm Hg, or jet velocity > 4.0
m/s)
4. Management of the Asymptomatic Patient with severe AS:
1. Asymptomatic patients have mortality outcomes similar to age-matched normal
adults. Therefore the risks of surgery generally outweigh the benefits.
2. However, disease progresses rapidly, requiring more frequent monitoring.
Recommended frequency of monitoring:
a. Mild AS: TTE every 3-5 years
b. Moderate AS: every 1-2 years
c. Severe AS: every year
3. Medical therapy has not been shown to prevent or delay the disease process.
4. Aortic valve replacement in asymptomatic patients is controversial, though there
is general agreement that asymptomatic patients with normal LV systolic function
should NOT undergo valve replacement.
5. Potential exception: patients with clinical or echocardiographic parameters
suggestive of rapid disease progression. This is indicated by:
a. Aortic jet velocity > 0.3 m/s or decrease in valve area > 0.1 cm2/year.
b. ECG with LVH and echo showing smaller aortic valve area predict
development of early symptoms.
6. Exercise testing can identify limited exercise capacity, abnormal blood pressure
responses, or exercise induced symptoms in patients with severe AS, and may
assist in determining who may benefit from early surgery (ACC/AHA Class IIb
indication).
†see classification scheme below
5. Management of the Symptomatic Patient with severe AS:
1. Aortic valve replacement (AVR) is the only effective treatment. Younger patients
with congenital of rheumatic AS may be candidates for valvotomy. AVR
dramatically improves both symptoms and survival.
2. Indications for Aortic Valve Replacement (ACC/AHA Class I indications)*:
a. Severe AS and symptomatic
b. Severe AS undergoing concurrent CABG
c. Severe AS undergoing surgery of the aorta or other heart valves
d. Severe AS with LV dysfunction (EF < 50%)
*assuming no severe comorbities. Age is NOT a contraindication to surgery.
Algorithm for approaching severe AS:
Bonow et al. ACC/AHA Practice Guidelines 2006. JACC;48 (3):e1-148.
6. Other indications for AVR:
1. Moderate AS undergoing CABG or surgery on aorta or other heart valves (Class
IIa).
2. Mild AS undergoing CABG when there is evidence of moderate to severe valve
calcification (Class IIb).
3. Asymptomatic severe AS when patient’s expected operative mortality is 1.0% or
less (Class IIb).
†
ACC/AHA Classification of recommendations:
Class I indication: procedure should be performed
Class IIa: reasonable to perform procedure
Class IIb: may consider procedure
Class III: no benefit
Review Question:
1. An 82-year-old woman presents for her annual examination. She has hypertension and
is on chronic β-blocker therapy. She denies all cardiac symptoms. She takes a daily 1mile walk, and her exercise tolerance has not changed during the past year. Physical
examination shows a blood pressure of 138/86 mm Hg, a regular pulse of 80/min, and a
respiratory rate of 16/min. Her JVP is 10 cm H2O, her carotid upstrokes are normal, and
her lungs are clear. Cardiac examination reveals a normal S1, a single S2, and a grade 3/6
early systolic murmur at the upper left sternal border radiating to her carotids. Abdominal
examination is benign, and there is 1+ peripheral edema. Lab data are remarkable for a
total cholesterol of 210 mg/dL, with an LDL cholesterol of 110 mg/dL. Her echo from 2
years ago showed moderate calcific aortic stenosis, with a maximum aortic velocity of
3.6 m/s (normal < 1.5 m/s) a mean gradient of 30 mm Hg (normal < 5 mm Hg) and a
valve area of 1.2 cm2 (normal > 2 cm2) with normal left ventricular systolic function.
Echo now shows a maximum aortic jet velocity of 4.2 m/s, mean gradient of 44 mm Hg,
and a valve area of 1.0 cm2 and normal ejection fraction.
Which is the most appropriate next step?
A. Reassurance
B. Begin a cardiac rehabilitation program
C. Begin hydrochlorothiazide
D. Start statin therapy
E. Refer for aortic valve replacement
Correct choice is A. Although she has severe AS on echo, she remains asymptomatic
and has normal exercise tolerance. Reassurance is appropriate. Her physical findings
show the classic systolic murmur and single S2 of severe AS. The classic decrease and
delay in carotid upstrokes is often obscured by increased vessel rigidity in elderly patients
with hypertension. The rate of progression of calcific AS in this patient is typical. On
average, the aortic velocity increases by 0.3 m/s per year, mean gradient increases by 7
mm Hg per year, and valve area decreases by 0.1 cm2 per year, as seen in this patient. As
long as she remains asymptomatic, her survival is similar to age-matched normal adults;
once symptoms occur, however, valve replacement is indicated.
A cardiac rehabilitation program is not needed because this patient is active and
has had no recent cardiac events. Although medical therapy for hypertension is
appropriate in asymptomatic patients with AS, caution is needed as peripheral
vasodilation may not be met with a compensatory increase in stroke volume across the
stenosed valve, resulting in hypotension. Diuretics may further decrease the volume of a
small hypertrophied ventricle, with the resultant decrease in cardiac output leading to
symptoms. Her blood pressure control is adequate so additional medical therapy is not
needed, especially given the concerns with these medications when AS is present.
Currently, no medical therapy delays or halts progression of disease in the valve
leaflets of patients with calcific AS. It has been hypothesized that statins might be
beneficial earlier in the disease course, and clinical trials are currently in progress. Until
these studies are complete, statin therapy should be initiated only for standard indications
in patients with aortic stenosis.
2. 79-year-old woman is seen for an annual examination. She is in good health except for
osteopenia, for which she takes calcium and Vitamin D supplements. She walks regularly
to and from the bus stop several times per week. It takes her 25 minutes to get to the bus
stop whereas it only took her 10 minutes a year ago. She describes dyspnea midway in
her walk, causing her to stop and catch her breath. She denies angina, presyncope,
syncope, or pedal edema. Physical examination shows a heart rate of 80/min, blood
pressure of 165/86 mm Hg. Lungs are clear to auscultation. Carotid artery upstrokes are
delayed. There is a sustained apical impulse. S1 is normal and there is a single S2 and an
S4. A 3/6 late-peaking systolic murmur is heard best at the right 2nd intercostal space,
with radiation into the right carotid artery. Transthoracic echo shows concentric left
ventricular hypertrophy. The ejection fraction is 69% with no regional wall motion
abnormalities. There is a trileaflet aortic valve with heavy calcification, an aortic jet
velocity of 4.8 m/s, a peak transaortic gradient of 92 mm Hg, and a valve area of 0.7 cm2.
Which is the most appropriate option for improving this patient's quality of life?
A. Begin an angiotensin-converting enzyme inhibitor
B. Percutaneous aortic balloon valvuloplasty
C. Aortic valve replacement
D. A supervised cardiac exercise program
E. Discontinue calcium supplementation
Correct choice is C.
Echocardiographic criteria are consistent with severe AS. This patient has
symptomatic disease with exertional dyspnea and decreased exercise tolerance. Referral
for aortic valve replacement should be the next step in her management.
In general, medical management alone is not indicated in symptomatic AS
patients given the dismal prognosis if valve replacement is delayed. In a study of
symptomatic patients with AS who refused surgery, average survival was only 2 years,
with a 5-year survival of less than 20%. In contrast, prognosis in patients with
asymptomatic disease is excellent. Therefore, current guidelines drafted by the
ACC/AHA advocate aortic valve replacement only once cardiac symptoms are present.
ACE inhibitors are relatively contraindicated in significant AS because afterload
reduction may increase the effective pressure gradient across the stenotic aortic valve.
Percutaneous aortic balloon valvuloplasty may initially provide a modest decrease in the
outflow gradient, but there is often significant residual obstruction from leaflet thickening
and annular calcification, recurrent stenosis typically occurs within months, and clinical
trials to date have not demonstrated a beneficial effect on long term outcome. Initiating a
supervised cardiac exercise program is a useful adjunct to improve exercise tolerance in
patients that are debilitated or deconditioned. This patient has symptomatic AS, and a
cardiac exercise program will not change her valvular parameters or cardiopulmonary
symptoms preoperatively. A supervised cardiac exercise program would, however, be
indicated following aortic valve replacement to limit postoperative deconditioning. Oral
calcium supplementation does not accelerate the progression of valvular calcification;
therefore, calcium therapy should not be discontinued.
Post Module Evaluation
Please place completed evaluation in an interdepartmental mail envelope and address to
Dr. Wendy Gerstein, Department of Medicine, VAMC (111).
1) Topic of module:__________________________
2) On a scale of 1-5, how effective was this module for learning this topic? _________
(1= not effective at all, 5 = extremely effective)
3) Were there any obvious errors, confusing data, or omissions? Please list/comment
below:
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
4) Was the attending involved in the teaching of this module? Yes/no (please circle).
5) Please provide any further comments/feedback about this module, or the inpatient
curriculum in general:
6) Please circle one:
Attending
Resident (R2/R3)
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