Case Example: Aortic Stenosis

Question: Does my patient have significant aortic stenosis?

A 72 year-old woman with a history of CHF presents with several weeks of gradually progressive DOE. At her baseline, she is able to walk several blocks, but now feels winded. She denies chest pain, palpitations, syncope/near syncope, cough, orthopnea, or PND. She states she is compliant with her medications and diet. She has had a recent functional study that showed minimal ischemia.

Meds aspirin
digoxin 0.125 qd
lisinopril 20 mg qd
furosemide 20 mg qd
KCl 10 mEq qd
PE HR 90, regular
PB 134/70
Labs chem 7:
Na 132
K 5
Cl 94
HCO3 30
BUN 18
Cr 1.3
CBC: notable for Hgb 14 g/dL (Hct 43%)
CV RRR, normal S1 and S2
No S3 but has S4
2/6 mid-peaking systolic murmur at the LUSB that radiates to the carotids.

PMI is mildly enlarged and sustained
Neck Carotid pulse is brisk.
JVP flat
Positive abdominojugular reflux
CXR Xray shows cardiomegaly and mild vascular redistribution
ECG Unchanged with an incomplete LBBB pattern

Clinical Diagnosis

Worsening of her congestive heart failure (positive AJR, enlarged and sustained PMI, cardiomeagly , and vascular redistribution).

Clinical Questions

Is this patient's worsening CHF due to significant aortic stenosis?
  • Implications for major management decisions; survey vs. medical management
  • Implications for acute medical management: use of preload reduction, afterload reduction.

Evidence-Based Medicine Approach

Critical appraisal of this study:
  1. Was there an independent, blind comparison with a criterion ("gold") standard?
  2. Was the diagnostic test evaluated in a clinically relevant spectrum of patients?
  3. Was the criterion standard applied regardless of the result of the diagnostic test? Did everyone receive the same gold standard diagnostic test?
    (Gaeschke, et al.)
Literature Search:
Medline Search (using PubMed's new interface (2001):

      MeSH Major Topic:
      Aortic stenosis,
      limited to AGE>64,
      Language = English,
      Subject = Human

      MeSH Major Topic: Physical Examination

Results: 28 citations.

One of these articles seems particularly suited to our clinical question:
Aronow, WS, and I Kronzon. Correlation of prevalence and severity of valvular aortic stenosis determined by continuous-wave Doppler echocardiography with physical signs of aortic stenosis in patients 62 to 100 years with aortic systolic ejection murmurs. Am J Cardiol 1987. 60(4):399-401.

Study

5 unselected elderly patients in a chronic care facility were found to have a systolic ejection murmur. They underwent examination by cardiologists and then echocardiography.

Critical appraisal of this study

  1. Good criterion standard (echo)--it is unclear whether the cardiologists and echocardiographers were blinded. In the methods section, the two studies are reported as being performed independently.
  2. Relevant clinical population
  3. Criterion standard was uniformly applied.
Results:

Significant aortic stenosis was diagnosed in 18/75 patients with a systolic ejection murmur in this population (defined as a peak gradient of greater than or equal to 25 mm Hg). The prevalence of the target disorder was 24%. Severe stenosis was diagnosed in 4/75 patients (peak gradient greater than or equal to 50 mm Hg) (prevalence of 5%).

Finding Sensitivity Specificity LR+ LR-
Prolonged carotid upstroke .72 .98 40.1 .3
Prolonged duration of murmur .78 .98 43.2 .2
Late peaking murmur .78 .98 43.2 .2
Radiation to the R carotid .95 .025 1.3 .2
Decreased or absent A2 .78 .98 43.2 .2
Presence of an S4 .56 .68 1.75 .6

Summary

In this study, prolonged carotid upstroke (pulsus tardus), long murmur, late-peaking murmur, and diminished S2 all had very high positive likelihood rations for significant aortic stenosis (principally because of their very high specificity; LR+ = Sens / 1 - Spec).

Most of these finding would increase your diagnostic suspicion of aortic stenosis (except the presence of an S4 - LR+ of only 1.75). The presence or absence of an S4 is not particularly helpful in the elderly. An S4 is a more specific diagnostic sign in younger patients (where there are fewer reasons for someone to have an S4).

The presence of radiation to the right carotid was not helpful if present, but it is a very sensitive test, and therefore, rules out the diagnosis in its absence ("SnNOUT").

Bayes Theorem:

Pre-test probability = 0.24 or 24%
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