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J Thorac Cardiovasc Surg 2001;122:583-586
© 2001 The American Association for Thoracic Surgery
Surgery for Acquired Cardiovascular Disease (ACD) |
From Cardiothoracic Centre, All India Institute of Medical Sciences, New Delhi, India.
Received for publication Dec 1, 2000. Revisions requested Jan 16, 2000; revisions received March 21, 2001. Accepted for publication March 23, 2001. Address for reprints: Arkalgud Sampath Kumar, Professor, Department of Cardiothoracic & Vascular Surgery, Cardiothoracic Centre, AIIMS, Ansari Nagar, New Delhi—110 029, India (E-mail: askumar{at}medinst.ernet.in).
Abstract
Objective: This study was performed to assess the long-term outcome of untreated mild aortic valve disease present at the time of initial mitral valve intervention.
Methods: A total of 284 patients with rheumatic heart disease aged 7 to 62 years (mean, 23.5 ± 12.2 years) who underwent mitral valve intervention and had mild aortic valve disease initially were followed up for 2 to 18 years (mean, 10.8 ± 3.7 years). At initial intervention, 232 patients had pure mild aortic regurgitation, and 52 patients had mild aortic stenosis with or without aortic regurgitation.
Results: Among patients with mild aortic regurgitation initially, 11 (5%) patients progressed to moderate (n = 6) or severe (n = 5) regurgitation over an interval of 9 to 17 years (mean, 12.1 ± 2.8 years), and 1 patient had moderate aortic stenosis and severe aortic regurgitation after 10 years. Freedom from development of moderate-severe aortic valve disease in patients who initially had mild aortic regurgitation was 100%, 97.0% ± 1.7%, and 87.4% ± 4.6% at 5, 10, and 15 years, respectively. Seventeen (35%) patients with initial mild aortic stenosis (with or without regurgitation) had moderate or severe stenosis (with or without moderate-severe regurgitation) after an interval of 4.9 ± 3.8 years. Freedom from development of moderate-severe aortic valve disease in patients who initially had mild aortic stenosis was 75.6% ± 6.2%, 61.5% ± 8.5%, and 46.1% ± 11.2% at 5, 10, and 15 years, respectively. Ten patients required aortic valve replacement for aortic valve dysfunction.
Conclusions: Mild aortic regurgitation present at the time of mitral valve intervention progresses very slowly and less frequently requires reintervention. However, mild aortic stenosis diagnosed initially progresses more often and more rapidly and thus needs closer follow-up.
In a significant proportion of patients with rheumatic heart disease, both the aortic and the mitral valves are involved.
1 If both valves are severely diseased, the management is simple. The problem arises when one of the valves is diseased only mildly and may not need any intervention if present in isolation. Such a dilemma is frequently encountered at the time of the mitral valve operation, when the aortic valve is found to be mildly diseased. 2 We reviewed our experience over the last 20 years with patients who underwent a mitral valve procedure and had mild aortic valve disease at initial presentation.
Patients and methods
From January 1979 through December 1997, 5274 patients underwent isolated mitral valve procedure. Patients who underwent preoperative cardiac catheterization-cineangiography were selected. Of these, 412 patients had mild aortic valve disease, as diagnosed with cineangiography-cardiac catheterization. Patients with inadequate follow-up (<2 years) and patients who died either early (
1 month) postoperatively or who within 2 years of the operation, primarily because of mitral prosthetic dysfunction, anticoagulation-related hemorrhage, or ventricular dysfunction, were excluded from the study. Similarly, patients who had preoperative left ventricular dysfunction (ejection fraction < 50%) or patients who had left ventricular dysfunction postoperatively were also excluded from the study. Patients having significant coronary artery disease at the time of initial diagnosis were also not included. Thus, a total of 284 patients were included in the study. Hospital records for these patients were carefully scrutinized. The demographic and clinical profile of the study group is shown in the Table 1.
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3 AR with grade +1 was considered of mild severity. Ejection fraction was calculated by the single-plane formula 4 or echocardiography. Mild AS was present in 18 patients, and mild AR was observed in 232 patients. Mixed stenosis and regurgitation was present in 34 patients. These patients underwent different mitral valve procedures, including mitral valve replacement (n = 154), mitral valve repair (n = 48), open mitral commissurotomy (n = 38), closed mitral valvotomy (n = 16), and balloon mitral valvotomy (n = 28).
Follow-up was assessed with either cardiac catheterization-cineangiography (n = 108) or, more recently, echocardiography (n = 176). On echocardiography, peak and mean transvalvular gradients were calculated with the Bernoulli equation by continuous-wave Doppler echocardiography. 5 Mean gradient across the aortic valve was used to define the severity of AS (mild 25 mm Hg; moderate 25-50 mm Hg; and severe > 50 mm Hg). In the absence of mean gradient, peak gradients (
50 mm Hg and 75 mm Hg) across the aortic valve were considered as moderate and severe AS. AR was graded according to published criteria as mild (grade I/II), moderate (grade III), and severe (grade IV). 6 Moderate-severe AS or AR was considered significant aortic valve disease.
Continuous or interval-related variables were expressed as mean values ± standard deviation. Categorical variables were expressed as percentages. Groups were compared by 
2 analysis and t tests. Actuarial estimates were calculated and compared by the Kaplan-Meier technique with log-rank tests. 7 Cox proportional hazard regression was used to analyze a number of variables for development of significant aortic valve disease in follow-up. These included age, sex, functional class, rhythm, diabetes mellitus, hypertension, smoking, hyperlipedemia, predominant mitral valve lesion (stenosis, regurgitation, or mixed), initial aortic valve lesion (stenosis or regurgitation), and type of mitral valve intervention. For the purpose of analysis, patients having mild AS with or without mild AR were considered in a single group. All statistical analysis was performed with the SPSS for Windows 6.0 software package (SPSS Inc, Chicago, Ill).
Results
Follow-up ranged from 2 to 18 years (mean, 10.8 ± 3.7 years). There were 29 late deaths caused by congestive heart failure (n = 9), prosthetic valve dysfunction (n = 5), anticoagulant-related hemorrhage (n = 3), cerebrovascular accident (n = 4), and noncardiac causes (n = 8).
In 29 patients aortic valve disease progressed to significant severity. In patients with mild AR initially, 11 (5%) patients progressed to significant AR (moderate AR in 6 and severe AR in 5) over an interval of 9 to 17 years (mean, 12.1 ± 2.8 years). An additional patient with mild AR initially had moderate AS and severe AR after a follow-up of 10 years. Freedom from development of moderate-severe aortic valve disease in patients who initially had mild AR was 100%, 97.0% ± 1.7%, and 87.4% ± 4.6% at 5, 10, and 15 years, respectively.
Among patients who had mild AS initially, 7 patients had significant AS (moderate AS in 4 and severe AS in 3) after a follow-up of 1 to 12 years (mean, 4.9 ± 4.2 years). Ten patients who had both mild AS and AR initially had significant aortic valve disease after a follow-up of 1 to 13 years (mean, 4 ± 3.5 years). This included severe AS (n = 1), moderate AS (n = 2), and combined moderate-severe AS and moderate-severe AR (n = 7). Thus, 17 (35%) patients with initial AS (with or without mild AR) progressed to significant disease over a duration of 1 to 13 years (mean, 4.9 ± 3.8 years). Freedom from development of moderate-severe aortic valve disease in patients who initially had mild AS was 75.6% ± 6.2%, 61.5% ± 8.5%, and 46.1% ± 11.2% at 5, 10, and 15 years, respectively. It was significantly less (P < .001) than those who had only mild AR initially (Figure 1). Similarly, the average duration for progression of aortic valve disease was significantly less in patients who had mild AS initially compared with those who had mild AR only (4.9 ± 3.8 vs 11.9 ± 2.7 years, P < .001).
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One patient with mild AS (plus mild AR) had infective endocarditis after 4 years. Endocarditis was treated successfully with antibiotics but resulted in residual moderate-severe AR. In 3 patients there was documented recurrence of rheumatic carditis, but the aortic valve disease remained unchanged.
A total of 23 patients underwent reoperation (Table 2) for isolated mitral valve dysfunction (n = 13), isolated aortic valve dysfunction (n = 4), and both mitral and aortic valve dysfunction (n = 6). Aortic valve lesions necessitating reoperation included severe AR (n = 1), moderate-severe AS (n = 5), and moderate-severe AS and moderate-severe AR (n = 4).
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Despite frequent occurrence of mild aortic valve disease at the time of initial mitral valve intervention in rheumatic patients, little is known about the fate of the aortic valve disease. Vaturi and colleagues 2 have found that mild aortic valve disease at the time of mitral valve operations rarely develops into hemodynamically significant disease, even after a long follow-up period. Only 15% (9/59) of their patients with mild aortic valve disease at the initial presentation had moderate or severe aortic valve disease over a follow-up of 1 to 33 years. Likewise, in our experience the patients who initially had pure mild AR rarely had significant aortic valve disease. Only 5% of the patients with initial mild AR had moderate or severe AR/AS after an interval of 9 to 17 years (mean, 12.1 ± 2.8 years), and freedom from moderate or severe AR/AS was 87.4% ± 4.6% at 15 years. In contrast to this, patients who initially had mild AS (with or without AR) had moderate-severe aortic valve disease quite frequently. About 35% (17/52) of patients with initial AS (with or without AR) had moderate-severe aortic valve disease at a much shorter interval (range, 1–13 years; mean, 4.9 ± 3.8 years), and freedom from moderate or severe AR/AS was 46.1% ± 11.2% at 15 years. In our experience freedom from development of moderate-severe aortic valve disease in patients who initially had mild AS was significantly less than in those who had pure mild AR initially(Figure 1
). If the experience of Vaturi and colleagues is analyzed separately for mild AS and mild AR, 40% (3/7) of patients with initial mild AS (with or without AR) had moderate-severe AS or AR.
Very little information is available about progression of rheumatic AS. Most of the available reports discuss the natural history of congenital or degenerative AS. Rates of progression of mild AS are neither uniform nor predictable. 8 Serial assessment in various studies have shown no progression in some patients, with variable progression ranging from 0.1 to 0.3 cm2 per year decrease in valve area in others. 9-17 Thus, usually the progression of AS is slow, but in certain patients it may be remarkably rapid. Investigators have found progression of AS from the mild to the severe form in as little as 2 to 3 years. 10,13,18 Likewise, in our patients the AS progressed rapidly. This may be attributed to the younger age of our patients (mean, 23.5 years) in whom rheumatic heart disease follows a more aggressive course.
In our experience, at the time of initial evaluation, severity of AS was merely assessed by gradients across the aortic valve. No consideration was given to the aortic valve area. In the presence of severe mitral valve disease, the hemodynamic effects of AS remain masked, 19-24 and thus the measured gradients may have underestimated the severity of AS. In such conditions calculation of valve area in relation to cardiac output would have been a better index of severity of AS.
The aortic valve area in adults is about 3.0 cm2 (range, 2.6-3.6 cm2), and a gradient becomes detectable only when the valve area becomes less than 2.0 cm2. 8 Thus, there is a significant decrease in aortic valve area before gradients become detectable. 25 This represents advanced commissural fusion and valve deformity. This is in contrast to the presence of mild AR, which can occur even with slight deformity of one or more leaflets. Thus, the presence of mild AS signifies a greater degree of aortic valve disease than that of mild AR. Furthermore, turbulence caused by a stenotic valve may contribute to further leaflet damage and thus may lead to rapid progression of the disease.
Considering the drawbacks of double-valve replacement over mitral valve replacement alone, prophylactic aortic valve replacement may not be recommended for mild aortic valve disease. At the same time, patients with mild AS at the initial presentation should be considered potential candidates for rapid progression of aortic valve disease, and a closer follow-up is advised. However, these results were obtained in patients with rheumatic valvular disease, and hence these may not be generalized to patients with isolated aortic valve disease of other causes.
Acknowledgments
We thank Mr Rajvir Singh, MSc (Stat), for statistical analysis.
References
This article has been cited by other articles:
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  H. V. Schaff and R. M. Suri Multiple Valve Disease Card. Surg. Adult, January 1, 2008; 3(2008): 1129 - 1158. [Full Text]
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 S. K. Choudhary, S. Talwar, and A. S. Kumar Late outcome of mild or moderate aortic valve disease present at the time of mitral valve intervention Ann. Thorac. Surg., November 1, 2003; 76 (5): 1774 - 1775. [Full Text] [PDF]
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H. V. Schaff and D. H. Marsh Multiple Valve Disease Card. Surg. Adult, January 1, 2003; 2(2003): 1017 - 1045. [Full Text]
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