Interact CardioVasc Thorac Surg 2008;7:301-305. doi:10.1510/icvts.2008.175463
© 2008 European Association of Cardio-Thoracic Surgery
Best evidence topic - Valves |
Is it ever worth contemplating an aortic valve replacement on patients with low gradient severe aortic stenosis but poor left ventricular function with no contractile reserve?
Hariharan Subramanianb,
Babu Kunadiana and
Joel Dunningb,*
a Department of Cardiology, Hahneman University Hospital, Philadelphia, USA
b Department of Cardiothoracic Surgery, James Cook University Hospital, Middlesbrough, UK
Received 9 January 2008;
accepted 10 January 2008
*Corresponding author. Tel./fax: +44 780 1548122.
E-mail address: joeldunning{at}doctors.org.uk (J. Dunning), hsubrama{at}DrexelMed.edu (H. Subramanian).
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Abstract
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A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether it is worth performing aortic valve replacement in patients with severe aortic stenosis and poor left ventricular function but no contractile reserve on dobutamine stress testing. Altogether 251 papers were identified using the below mentioned search and all major international guidelines were included. Fourteen presented the best evidence to answer the clinical question. The author, journal, date and country of publication, patient group, relevant outcomes and weaknesses were tabulated. We conclude that patients with severe aortic stenosis and a contractile reserve of <20% improvement in stroke volume on dobutamine stress testing have a very poor prognosis of only 10–20% at two years. Heart transplant would offer the best chance of survival to those eligible but for those not eligible, a surgical option should not be discounted for selected patients. The American Heart Association guidelines state that prognosis is very poor for either medical or surgical treatment, but the European Society of Cardiology guidelines state that surgery can be performed in these patients but should take into account the clinical condition of the patient. The operative mortality is around 30% and the French Multicentre study on low gradient aortic stenosis has shown that if the patient survives there is likely to be an improvement in symptoms and ejection fraction. Thus, absence of contractile reserve on stress testing does not exclude myocardial recovery after surgery, although it is a strong predictor for operative mortality. It should be noted that surgery has only been reported in very few of these patients to date. B-natriuretic peptide has also been suggested as a further marker of better prognosis in these high-risk patients in one small study.
Key Words: Evidence-based medicine; Aortic valve stenosis; Congestive heart failure; Thoracic surgery
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1. Introduction
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A best evidence topic was constructed according to the structured protocol. This protocol is fully described in the ICVTS [1].
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2. Clinical scenario
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You have been asked to evaluate a previously very fit 65-year-old ex-mountaineer for aortic valve replacement (AVR). He first presented to the cardiologists in pulmonary oedema two weeks ago although he tells you that he has been getting gradually worse for three years. The transthoracic echo revealed an effective orifice area (EOA) of his aortic valve of 0.7 cm2, left ventricular ejection fraction of 30%, and mean transaortic pressure difference of 25 mmHg. The cardiologists performed a dobutamine stress echocardiography (DSE) that revealed a minimal rise in the systolic velocity integral (15%) and no increase in the EOA. The cardiologists feel that he is beyond the point at which an AVR would help him, but would value your opinion.
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3. Three-part question
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In [Patients with severe aortic stenosis, poor left ventricular function and no reversibility] is an [Aortic Valve Replacement superior to medical therapy] to improve [Survival or symptoms].
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4. Search strategy
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Medline 1950–Nov 2007.
[exp Aortic Valve Stenosis/OR aortic stenosis.mp] AND [exp Ventricular Dysfunction, Left/OR left ventricular dysfunction.mp OR exp Dobutamine OR Dobutamine stress.mp OR exp Heart Failure, Congestive/] AND [Thoracic Surgery.mp OR exp Thoracic Surgery/OR AVR.mp OR valve replacement.mp].
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5. Search outcome
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A total of 251 papers were found. In addition, all major guidelines were included and their reference lists searched. Fourteen papers were deemed to represent the best evidence on the topic and are summarized in Table 1.
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6. Discussion
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Low gradient low flow aortic stenosis is defined by the American Heart Association as aortic stenosis with an effective aortic area <1 cm2, left ventricular ejection fraction <40% and mean transaortic pressure gradient of <30 mmHg. Assessment by dobutamine stress testing is essential to verify that the reduced effective orifice area is in fact severe rather than an effect of low flow on a mild or moderately stenosed valve [2]. Contractile reserve on dobutamine stress testing is defined by an increase in the systolic velocity integral or stroke volume by at least 20% during dobutamine infusion. Aortic valve replacement is recommended by the AHA for patients with low gradient, low flow aortic stenosis with contractile reserve (Class I: level of evidence C).
For patients without contractile reserve, the most comprehensive studies have been performed by the French Multicentre study on low gradient aortic stenosis by Quere, Monin and colleagues. In the study by Monin et al. in 2001 [3], the perioperative mortality of patients without contractile reserve undergoing AVR was about 50% but the number of patients in this subgroup was only six, and no definitive conclusions could be reached. In their largest study published in 2003 [4] involving 136 patients, Kaplan–Meier analysis of patients without contractile reserve showed a 2-year survival rate of 35% of those undergoing AVR and 15% treated medically. The most recent report by Quere et al. [5] where 20 patients without contractile reserve had an AVR, concluded that LV dysfunction and functional status can improve significantly after AVR even in patients with no contractile reserve although their operative mortality is around 30%. In a study by Nishimura et al. [6], about one-third of the patients without contractile reserve died perioperatively while another third died at months 25 and 34. Again the number of patients in this subgroup without contractile reserve who underwent AVR was very small – 6, statistically not significant.
The Topas Study (Truly Or Pseudosevere Aortic Stenosis) [7] found in a cohort study of 69 patients, of whom 29 had an aortic valve replacement that poor contractile reserve was not a surgical predictor of mortality compared to patients with contractile reserve as long as the BNP was <550 pg/ml. This was, however, a very small subset analysis.
The American Heart Association guidelines state that the mortality is very high in patients with no contractile reserve either with or without surgery. The European Society of Cardiology agrees with this but also states that surgery can be performed but should take into account the patient's co-morbidities [8, 9].
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7. Clinical bottom line
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It is clear that patients with severe aortic stenosis and a contractile reserve of <20% improvement in stroke volume on dobutamine stress testing have a very poor prognosis of only 10–20% at two years. Heart transplant would offer the best chance of survival to those eligible but for those not eligible, a surgical option should not be discounted for selected patients. The operative mortality is, however, around 30% but the French Multicentre study on low gradient aortic stenosis has shown that if the patient survives there is likely to be an improvement in symptoms and ejection fraction. Thus, absence of contractile reserve on stress testing does not exclude myocardial recovery after surgery, although it is a strong predictor for operative mortality.
It should be noted that surgery has only been reported in very few of these patients to date. B-natriuretic peptide has also been suggested as a further marker of better prognosis in these high-risk patients in one small study.
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References
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- de Filippi CR, Willett DL, Brickner ME, Appleton CP, Yancy CW, Eichhorn EJ, Grayburn PA. Usefulness of dobutamine echocardiography in distinguishing severe from nonsevere valvular aortic stenosis in patients with depressed left ventricular function and low transvalvular gradients. Am J Cardiol 1995;75:191–194.[CrossRef][Medline]
- Monin JL, Monchi M, Gest V, Duval-Moulin AM, Dubois-Rande JL, Gueret P. Aortic stenosis with severe left ventricular dysfunction and low transvalvular pressure gradients: risk stratification by low-dose dobutamine echocardiography. J Am Coll Cardiol 2001;37:2101–2107.[Abstract/Free Full Text]
- Monin JL, Quere JP, Monchi M, Petit H, Baleynaud S, Chauvel C, Pop C, Ohlmann P, Lelguen C, Dehant P, Tribouilloy C, Gueret P. Low-gradient aortic stenosis: operative risk stratification and predictors for long-term outcome: a multicenter study using dobutamine stress hemodynamics. [see comment]. Circulation 2003;108:319–324.[Abstract/Free Full Text]
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Abstract
1. Introduction