Heart Disease contractile reserve, then the valve is considered flow limiting and surgery is indicated. Recent data have suggested the use of BNP may provide prognostic data in the setting of poor LV function and aortic stenosis. A BNP > 550 pg/mL has been associated with a poor outcome in these patients regardless of the results of dobutamine testing.
``Prognosis & Treatment Following the onset of heart failure, angina, or syncope, the prognosis without surgery is poor (50% 3-year mortality rate). Medical treatment may stabilize patients in heart failure, but surgery is indicated for all symptomatic patients with evidence of significant aortic stenosis. Valve replacement is usually not indicated in asymptomatic individuals, though a class II indication is to operate once the peak valve gradient by Doppler exceeds 64 mm Hg or the mean exceeds 40 mm Hg. Stress testing and perhaps the use of BNP may help identify patients who deny symptoms but are actually compromised from a ventricular function standpoint. The surgical mortality rate for valve replacement is low, even in the elderly, and ranges from 2% to 5%. This low risk is due to the dramatic hemodynamic improvement that occurs with relief of the increased afterload. Mortality rates are substantially higher when there is an associated ischemic cardiomyopathy. Severe coronary lesions are usually bypassed at the same time, although there are little data to suggest this practice affects outcome. All patients should have normal lipid levels, usually with goal of an LDL of ≤ 100 mg/dL, since progression of aortic stenosis theoretically may be slowed by control of cholesterol levels. Most studies have been negative or equivocal in this regard, but longer-term studies in patients with early disease are still pending. Many experts argue that for lipid lowering therapy to have any effect on the stenotic process, it needs to be initiated at an early stage in the disease. If patients with aortic stenosis have concomitant CAD, the LDL goal should be ≤ 70 mg/dL. Control of systemic hypertension is also an important adjunct, and inadequate systemic BP control is common due to unreasonable concerns about providing too much afterload reduction in patients with aortic stenosis. The interventional options in patients with aortic stenosis are variable and dependent on the patient’s lifestyle and age. In the young and adolescent patient, percutaneous valvuloplasty still has a role. Balloon valvuloplasty is less effective and is associated with early restenosis in the elderly, and thus is rarely used except as a temporizing measure in calcific aortic stenosis. Data suggest aortic balloon valvuloplasty in the elderly has an advantage only in those with preserved LV function, and such patients are usually excellent candidates for surgical AVR. The Ross procedure is generally still considered a viable option in younger patients, and it is performed by moving the patient’s own pulmonary valve to the aortic position and replacing the pulmonary valve with a homograft (or rarely a bioprosthetic valve). However, dilation of the pulmonary valve autograft and consequent aortic regurgitation, plus early stenosis of the pulmonary homograft in the pulmonary position, has reduced the enthusiasm for this approach
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in most institutions. Middle-aged adults generally can tolerate the anticoagulation therapy necessary for the use of mechanical AVR, so most undergo AVR with a bileaflet mechanical valve. If the aortic root is severely dilated as well (>4.5 cm), then the valve may be housed in a Dacron sheath (Bentall procedure) and the root replaced. Alternatively, a human homograft root and valve replacement can be used. In the elderly, bioprosthetic (either porcine or bovine pericardial) valves with a life expectancy of about 10–15 years are routinely used instead of mechanical valves to avoid need for anticoagulation. Recent data favor the bovine pericardial valve over the porcine aortic valve. If the aortic annulus is small, a bioprosthetic valve with a short sheath can be sewn to the aortic wall (the stentless AVR) rather than sewing the prosthetic annulus to the aortic annulus. (Annulus is a relative term when speaking of the aortic valve, since there is no true annulus.) Another surgical option becoming popular is the Wheat procedure; it involves aortic root replacement above the coronary arteries and AVR. The coronary arteries thus remain attached to the native aorta between the new graft and prosthetic valve rather than being reimplanted onto an artificial sheath or homograft. In patients with a bicuspid aortic valve, there is often an associated ascending aortic aneurysm. If the maximal dimension of the aortic root exceeds 5.0 cm, it is recommended to proceed with root replacement regardless of the severity of the aortic valve disease. The aortic valve may be replaced at the same time or may be left alone (valve sparing operation). Anticoagulation is required with the use of mechanical valves, and the international normalized ratio (INR) should be maintained between 2.0 and 3.0 or between 2.5 and 3.5, depending on type and position of valve and patient risk factors. In general, mechanical aortic valves are less subject to thrombosis than mechanical mitral valves. Some newer bileaflet mechanical valves (On-X) that require either no or a reduced dose of warfarin therapy are being evaluated, although the final data regarding the safety of this particular design are not available. The Prospective Randomized On-X valve AntiCoagulation Trial (PROACT) was begun in 2006 and is ongoing. Preliminary results have been reported and are very promising. Transcutaneous aortic valve implantation (TAVI) is being used in Europe. In the United States, the Food and Drug Administration (FDA) has granted limited approval for one device (Edwards SAPIEN), and trials of a second device (CoreValve) are being completed. The devices use either a stent with a trileaflet bovine pericardial valve constructed in it or a stent with a large valve from a cow’s jugular vein mounted inside. Both a retrograde approach (from the aorta or from the subclavian artery) and an antegrade approach (from the ventricles by way of a transseptal catheter across the atrial septum) are being investigated. The Edwards SAPIEN valve is a balloon- expandable valvular stent, while the CoreValve is a self- expanding valvular stent. The PARTNER TAVI trial randomized 358 high-risk patients who were not considered to be candidates for surgical AVR to either the TAVI or the medical therapy group. Confirming historical data, the medically treated patients had 50% mortality at 1 year,