28 Apr

The Natural History and Rate of Progression of Aortic Stenosis: Symptoms and Survival

The hemodynamic burden of aortic stenosis is primarily a pressure load to the left ventricle. In accordance to the law of Laplace (wall stress = [pressure X radius]/2X wall thickness), as left ventricular pressure increases, in order to maintain wall stress, ventricular wall thickness must increase. If the increase in wall thickness is unable to match the rise in left ventricular pressure, wall stress (afterload) increases, which impairs ventricular performance. This phenomenon is referred to as afterload mismatch. Systolic dysfunction in aortic stenosis is largely a result of afterload mismatch. Transval-vular flow has two determinants: pressure gradient and orifice area. Therefore, one must interpret with caution literature that defines the severity of aortic stenosis solely on the basis of a high pressure gradient as a proportion of patients with poor left ventricular systolic function, and thus low gradients may be missed. The prognosis of these patients is worse than those with preserved left ventricular systolic function.
Recognizing some of its limitations, what can one discern from the literature?
Symptoms and Survival
Symptomatic Aortic Stenosis: The cardinal manifestations of aortic stenosis include syncope, angina pectoris, and dyspnea. Once these symptoms develop, the prognosis is poor. The onset of angina, syncope, and dyspnea has been shown to correlate with an average time to death of 5, 3, and 2 years, respectively. This clinical course has been derived primarily from postmortem studies on adults with acquired aortic stenosis’ (Fig 1). The average age at death of these patients was 63 years.

Minimally Symptomatic or Asymptomatic Aortic Stenosis: As technology advances so, too, do our clinical tools of observation. The routine use of cardiac catheterization and the availability of Doppler echocardiography facilitates the diagnosis of aortic stenosis. Clinical findings suggestive of aortic stenosis can be confirmed easily. As a result, many patients with limited or no symptoms yet hemody-namically significant aortic stenosis are being identified. The dilemma is how best to treat these patients.

Figure 1. Average course of valvular aortic stenosis in adults. Data assembled from postmortem studies. Reprinted with permission from Ross and Braunwald.

Figure 1. Average course of valvular aortic stenosis in adults. Data assembled from postmortem studies. Reprinted with permission from Ross and Braunwald.

Categories: Aortic Stenosis
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