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1
Question:

A 75-year-old man is being evaluated for a heart murmur.  He has had no exertional chest pain, shortness of breath, palpitations, fatigue, dizziness, or syncope.  The patient's only other medical condition is hypertension, for which he takes chlorthalidone and amlodipine.  He has a 20-pack-year smoking history but quit 25 years ago.  Temperature is 36.9 C (98.4 F), blood pressure is 130/80 mm Hg, pulse is 80/min, and respirations are 16/min.  Physical examination shows a sustained apical impulse.  S1 is normal; a single, soft S2 and an S4 are present.  A grade 3/6 late-peaking systolic murmur is heard best at the right 2nd intercostal space, with radiation to the right carotid artery.  Carotid pulses are delayed.  Transthoracic echocardiogram shows a thickened left ventricular wall with no regional wall motion abnormalities.  The ejection fraction is 45%.  There is a trileaflet aortic valve with heavy calcification, valve area of 0.9 cm2, and transvalvular gradient consistent with severe aortic stenosis.  Which of the following is the most appropriate next step in management of this patient?

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Explanation:

Valve replacement in aortic stenosis

Severe AS criteria

  • Aortic jet velocity ≥4.0 m/sec, or
  • Mean transvalvular pressure gradient ≥40 mm Hg
  • Valve area usually ≤1.0 cm2 but not required

Indications for valve replacement

Severe AS & ≥1 of the following:

  • Onset of symptoms (eg, angina, syncope)  
  • Left ventricular ejection fraction <50%
  • Undergoing other cardiac surgery (eg, CABG)

AS = aortic stenosis; CABG = coronary artery bypass grafting.

Severe aortic stenosis (AS) is diagnosed based on aortic jet velocity or mean transvalvular pressure gradient; in most cases the valve area is ≤1 cm2, but valve area is not considered for diagnosis.  Physical examination findings that suggest severe AS include a late-peaking, crescendo-decrescendo systolic murmur best heard at the right upper sternal border and diminished and delayed pulses (pulsus parvus et tardus).  Patients with severe AS often have symptoms of angina, syncope/presyncope, or heart failure (eg, dyspnea).

Surgical aortic valve replacement (AVR) should be considered in patients with severe AS and ≥1 of the following criteria:

  • Presence of symptoms attributable to AS:  Patients with symptomatic, severe AS have a relatively high risk of sudden cardiac death.
  • Left ventricular ejection fraction (LVEF) <50%, regardless of symptoms (as in this patient with LVEF 45%):  A depressed LVEF is often due to excessive afterload created by the stenotic valve, and it frequently normalizes with AVR.
  • Undergoing other cardiac surgery (eg, coronary artery bypass grafting):  The valve can be repaired concomitantly.

The definition of severe AS encompasses many patients who are asymptomatic because it was designed to identify nearly all patients who may benefit from AVR (high sensitivity).  Some of these patients are truly asymptomatic.  Others lack symptoms only because of a sedentary lifestyle; when subjected to exertion (eg, stress testing) they have typical severe AS symptoms.

(Choice A)  Serial echocardiography is appropriate in patients with severe AS who are truly asymptomatic and have normal LVEF, but not in this patient with LVEF <50%.

(Choice B)  Severe AS is a progressive disease that requires either prompt AVR or close monitoring; reassurance alone is not appropriate.

(Choices D and E)  Severe AS creates a tenuous hemodynamic situation because adequate preload is required to maintain cardiac output and adequate diastolic pressure is required to maintain coronary artery perfusion.  This limits the use of medical therapy because diuretics (eg, furosemide) reduce preload and vasodilators (eg, amlodipine, hydralazine, ACE inhibitors) reduce diastolic pressure, often precipitating clinical decompensation.  Cardiac exercise programs are also of limited benefit.  AVR is the only therapy proven to improve survival in patients with severe AS.

Educational objective:
In patients with severe aortic stenosis, surgical aortic valve replacement is indicated in all symptomatic patients.  It is also indicated in asymptomatic patients with left ventricular ejection fraction <50% and those undergoing other cardiac surgery.