Aortic stenosis natural history, complications and prognosis
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Aortic Stenosis Microchapters |
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Percutaneous Aortic Balloon Valvotomy (PABV) or Aortic Valvuloplasty |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editors-In-Chief: Mohammed A. Sbeih, M.D. [2]; Lakshmi Gopalakrishnan, M.B.B.S. [3]
Overview
Left untreated, aortic valve stenosis can lead to angina, syncope, congestive heart failure, atrial fibrillation, endocarditis, and sudden cardiac death. Surgical treatment of aortic stenosis also carries risks and potential complications including vascular complications and mitral valve injury.
Natural History
Aortic stenosis due to degeneration of a calcified aortic valve has a prolonged latent period during which time symptoms may be minimal or even lacking [1]. The average rate of progression in valvular aortic stenosis, once moderate stenosis is present and symptomatic, is a decrease in valve area of 0.1 cm2 per year [2]. Also on average, there is an increase in the jet velocity of 0.3 m / second per year and an increase in the mean pressure gradient of 7 mm Hg per year [3] [4][5]. There is tremendous individual variability in the rate of progression of aortic stenosis.
The rate of progression of AS can be faster in patients with degenerative calcific disease than in those with congenital or rheumatic disease [6]. Progression to AS may occur in patients with aortic sclerosis, defined as valve thickening without obstruction to ventricular outflow. Regular follow-up should be scheduled for all patients with mild to moderate AS, even for asymptomatic patients.
Impaired platelet function and coagulation abnormalities as decreased levels of Von Willebrand factor can be seen in most patients with severe AS. This resolves after valve replacement procedure. 20% of patients have clinical bleeding, most often epistaxis or ecchymoses [7].
If left untreated for a long time, Aortic stenosis may lead to complications such as angina, syncope, or heart failure. The average survival is 2 to 3 years after the onset of symptoms [8][9][10],there is also a high risk of sudden death, which may occur without prior symptoms [8]. Sudden death is known to occur in less than 1% per year when patients with aortic stenosis are followed up prospectively [11]. Asymptomatic patients are treated conservatively, whereas corrective surgery (Aortic valvotomy or valve replacement) is generally recommended in patients with symptoms due to AS.
Progression of Aortic Stenosis
The rate of progression of aortic stenosis occurs at an average rate of reduction in aortic valve area of 0.1 cm2 in valve area per year [1]. Unfortunately, there is a large interpatient variability in the rate of progression. Furthermore, multiple factors are associated with more rapid progression which include the following:
- Left ventricular function
- Bicuspid aortic valve stenosis presents one to two decades earlier
- Initial severity of stenosis
- Risk factors for atherosclerosis, such as age, smoking, hypertension, obesity and diabetes, lipid abnormalities, chronic renal failure and dialysis, and atherosclerotic disease itself, such as concomitant coronary artery disease
Complications
Possible complications for untreated aortic stenosis include:
- Arrhythmias.
- Endocarditis.
- Left-sided heart failure.
- Left ventricular hypertrophy (enlargement) caused by the extra work of pushing blood through the narrowed valve.
- Atrial fibrillation.
- Myocardial infarction.
- Angina.
- Fainting (syncope).
Precautions
People with aortic stenosis of any aetiology are at risk for the development of infection of their stenosed valve, i.e. infective endocarditis. To lessen the chance of developing that serious complication, people with AS are usually advised to take antibiotic prophylaxis around the time of certain dental/medical/surgical procedures. Such procedures may include dental extraction, deep scaling of the teeth, gum surgery, dental implants, treatment of esophageal varices, dilation of esophageal strictures, gastrointestinal surgery where the intestinal mucosa will be disrupted, prostate surgery, urethral stricture dilation, and cystoscopy. Note that routine upper and lower GI endoscopy (i.e. gastroscopy and colonoscopy), with or without biopsy, are not usually considered indications for antibiotic prophylaxis.
Not withstanding the foregoing, the American Heart Association has recently changed its recommendations regarding antibiotic prophylaxis for endocarditis. Specifically, as of 2007, it is recommended that such prophylaxis be limited only to:
- Those with prosthetic heart valves.
- Those with previous episode(s) of endocarditis.
- Those with certain types of congenital heart disease [12].
Since the stenosed aortic valve may limit the heart's output, people with aortic stenosis are at risk of syncope and dangerously low blood pressure should they use any of a number of common medications. Ironically, these same medicines are used to treat a variety of cardiovascular diseases, many of which may co-exist with aortic stenosis. Examples include nitroglycerin, nitrates, ACE inhibitors, terazosin (Hytrin), and hydralazine. Note that all of these substances lead to peripheral vasodilation. Normally, however, in the absence of aortic stenosis, the heart is able to increase its output and thereby offset the effect of the dilated blood vessels. In some cases of aortic stenosis, however, due to the obstruction of blood flow out of the heart caused by the stenosed aortic valve, cardiac output cannot be increased. Low blood pressure or syncope may ensue.
Prognosis
30% reduction in gradient is expected as the immediate result of surgical intervention. Patient survival after repeat BAV is higher than that of untreated patients.
Low Flow Aortic Stenosis
If there is a decline in left ventricular function due to systolic dysfunction, there may be only a moderate transvalvular gradient or low flow aortic stenosis. If there is fibrosis of the left ventricle, there may be incomplete recovery after aortic valve replacement. This scenario can also occur among patients in whom there is a history of myocardial infarction: there is insufficient contractility to mount an aortic gradient.
Definition
- An aortic valve areas < 1.0 cm2
- A left ventricular ejection fraction < 40%
- A mean pressure difference or gradient across the aortic valve of < 30 mm Hg
With a dobutamine infusion, the aortic valve area should increase to > 1.2 cm2, and the mean pressure gradient should rise above 30 mm Hg. If there is a failure to acheive these improvements, early surgical mortality is 32-33%, but it is only 5–7% in those patients who can augment their contractility and gradient. Survival at five years was 88% after surgery if the patient can augment their contractility, but only 10–25% if the patient cannot augment their contractility.
It should be noted that left ventricular contractile reserve is a better predictor of surgical outcomes than markers of stenosis. Aortic valve surgery is indicated if there is severe AS along with an increase in the systolic velocity integral by >20% during a dobutamine infusion.
References
- ↑ 1.0 1.1 Faggiano P, Aurigemma GP, Rusconi C, Gaasch WH (1996). "Progression of valvular aortic stenosis in adults: literature review and clinical implications". Am Heart J. 132 (2 Pt 1): 408–17. PMID 8701905.
- ↑ Zoghbi WA, Enriquez-Sarano M, Foster E, Grayburn PA, Kraft CD, Levine RA; et al. (2003). "Recommendations for evaluation of the severity of native valvular regurgitation with two-dimensional and Doppler echocardiography". J Am Soc Echocardiogr. 16 (7): 777–802. doi:10.1016/S0894-7317(03)00335-3. PMID 12835667.
- ↑ Cheitlin MD, Gertz EW, Brundage BH, Carlson CJ, Quash JA, Bode RS (1979). "Rate of progression of severity of valvular aortic stenosis in the adult". Am Heart J. 98 (6): 689–700. PMID 495418.
- ↑ Jonasson R, Jonsson B, Nordlander R, Orinius E, Szamosi A (1983). "Rate of progression of severity of valvular aortic stenosis". Acta Med Scand. 213 (1): 51–4. PMID 6829320.
- ↑ Peter M, Hoffmann A, Parker C, Lüscher T, Burckhardt D (1993). "Progression of aortic stenosis. Role of age and concomitant coronary artery disease". Chest. 103 (6): 1715–9. PMID 8404089.
- ↑ Rosenhek R, Binder T, Porenta G, Lang I, Christ G, Schemper M; et al. (2000). "Predictors of outcome in severe, asymptomatic aortic stenosis". N Engl J Med. 343 (9): 611–7. doi:10.1056/NEJM200008313430903. PMID 10965007.
- ↑ Vincentelli A, Susen S, Le Tourneau T, Six I, Fabre O, Juthier F; et al. (2003). "Acquired von Willebrand syndrome in aortic stenosis". N Engl J Med. 349 (4): 343–9. doi:10.1056/NEJMoa022831. PMID 12878741.
- ↑ 8.0 8.1 Ross J, Braunwald E (1968). "Aortic stenosis". Circulation. 38 (1 Suppl): 61–7. PMID 4894151.
- ↑ Kelly TA, Rothbart RM, Cooper CM, Kaiser DL, Smucker ML, Gibson RS (1988). "Comparison of outcome of asymptomatic to symptomatic patients older than 20 years of age with valvular aortic stenosis". Am J Cardiol. 61 (1): 123–30. PMID 3337000.
- ↑ Iivanainen AM, Lindroos M, Tilvis R, Heikkilä J, Kupari M (1996). "Natural history of aortic valve stenosis of varying severity in the elderly". Am J Cardiol. 78 (1): 97–101. PMID 8712130.
- ↑ Chizner MA, Pearle DL, deLeon AC (1980). "The natural history of aortic stenosis in adults". Am Heart J. 99 (4): 419–24. PMID 7189084.
- ↑ http://www.americanheart.org/presenter.jhtml?identifier=4436