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Ann Thorac Surg 2008;85:89-93. doi:10.1016/j.athoracsur.2007.07.048
© 2008 The Society of Thoracic Surgeons
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Original Articles: Cardiovascular

Mitral Valve Disease Presentation and Surgical Outcome in African-American Patients Compared With White Patients

Paul L. DiGiorgi, MD, F. Gregory Baumann, PhD, Anne M. O’Leary, MSN, Charles F. Schwartz, MD, Eugene A. Grossi, MD, Greg H. Ribakove, MD, Stephen B. Colvin, MD, Aubrey C. Galloway, MD, Juan B. Grau, MD*

Department of Cardiothoracic Surgery, New York University School of Medicine, New York, New York

Accepted for publication July 18, 2007.

* Address correspondence to Dr Grau, Department of Cardiothoracic Surgery, NYU School of Medicine, 550 First Ave, Suite 9V, New York, NY 10016 (Email: juan.grau{at}med.nyu.edu).


   Abstract
Top
 Abstract
Introduction
 Patients and Methods
 Results
 Comment
 References
 
Background: Disparities associated with race, particularly African-American race, in access to medical and surgical care for patients with cardiac disease have previously been documented. The purpose of this study was to determine the presentation, etiology, and hospital outcome differences between African-American patients and white patients with regard to surgically corrected mitral valve disease.

Methods: All 1,425 adult patients who underwent first time, isolated mitral valvuloplasty or mitral valve replacement by the same group of surgeons at New York University Medical Center and Bellevue Hospital Center between 1993 and 2003 were studied.

Results: African Americans (n = 123, 8.6%) were significantly younger (45.6 ± 14.4 versus 60.5 ± 15.3 years) and had significantly higher incidences of diabetes mellitus, renal failure, congestive heart failure, endocarditis, and rheumatic mitral disease; whereas whites (n = 1,302, 91.4%) more commonly had degenerative mitral disease. African Americans were less likely to undergo mitral valvuloplasty. There were no significant differences in the incidences of postoperative complications or hospital mortality (2.4% African American versus 5.1% white, p = 0.19).

Conclusions: African Americans present for mitral valve surgery at a significantly younger age than whites and with higher incidences of many risk factors. Whether presentation at a significantly earlier age in African Americans is a result of failures in primary care or an enhanced susceptibility to the process of mitral disease and comorbidities remains to be determined. African Americans were less likely to undergo mitral valvuloplasty, which may have an effect on long-term outcome. Improved screening in this racial group will facilitate earlier referral, increasing the potential for mitral valvuloplasty.


   Introduction
Top
 Abstract
 Introduction
Patients and Methods
 Results
 Comment
 References
 
Previous studies have examined coronary artery disease risk factors and surgical outcomes among different ethnic and racial groups [1–3]. One report has investigated the influence of race on outcomes after isloated mitral or aortic valve replacement [4]. We are unaware, however, of any previous study that has examined mitral valve disease, its surgical treatment options (valve repair or replacement), and outcomes with respect to different racial groups.

Both the New York State Adult Cardiac Surgery Database and The Society for Thoracic Surgery National Adult Cardiac Surgery Database have demonstrated increasing volumes of mitral valve surgery as indications have expanded and outcomes improved. As the number of mitral valve procedures performed increases nationwide, the importance of timely and appropriate access to mitral valve care, especially among minorities, becomes a signficant public health concern.

In mitral valve surgery, it is now generally acknowleged to be preferrable whenever possible to repair the valve rather than to replace it [5]. Advantages of repair include improved hospital and long-term mortality, preservation of left ventricular function, avoidance of the need for long-term anticoagulation, decreased thromboembolic complications, lower risk of endocarditis, and long-term freedom from reoperation [6–15]. The presenting stage of valvular heart disease, however, significantly influences the possibility of repairing the valve, impacting both outcomes and the need for lifelong anticoagulation. Early referral for significant mitral valve disease optimizes the possibility of valve repair.

The purpose of this study was to perform a retrospective review evaluating the presenting conditions of patients with mitral valve disease to our cardiothoracic surgical service, the surgical choices, and their outcomes. It was hypothesized that patients racially designated as African American present at a later stage in their mitral disease when compared with patients racially designated as white, and that this factor affects outcomes.


   Patients and Methods
Top
 Abstract
 Introduction
 Patients and Methods
Results
 Comment
 References
 
Data were routinely prospectively collected in accordance with the requirements of the New York State Cardiac Surgery Reporting System, an audited database containing information on all patients undergoing surgery on the heart or great vessels in New York State. The data collected included information on demographics, operation, risk factors, complications, and discharge status. All patients 18 years of age or older who underwent first time, isolated mitral valve replacement or repair between 1993 and 2003 at New York University Medical Center or Bellevue Hospital Center were included in this study. The same group of surgeons performed all mitral operations at both hospitals. Exclusion criteria were repeat mitral valve replacement, concomitant coronary artery bypass graft surgery (CABG), surgery on another valve, and aortic surgery. Race was as determined by the patient or patient’s family, in accordance with the definition of race used by The Society for Thoracic Surgery national database. Mitral valve disease etiology was determined from clinical and pathology records.

This study was approved by the Institutional Review Board (April 16, 2006) with a waiver of individual consent.

Data were analyzed using SPSS software (version 13; SPSS, Chicago, Illinois). Continuous variables are expressed as the mean ± SD. Comparisons of continuous variables between groups were performed with the Student’s t test or nonparametric tests. Categorical variables were compared between groups with the chi-square or Fisher’s exact test. Statistical significance was set at p of 0.05 or less for all analyses.


   Results
Top
 Abstract
 Introduction
 Patients and Methods
 Results
Comment
 References
 
Between January 1993 and December 2003, 1,425 African-American and white patients were discharged after undergoing first time, isolated mitral valve replacement or repair at New York University Medical Center (1,316 patients; 1,240 white, 76 African American) or Bellevue Hospital Center (109 patients; 62 white, 47 African American). The same group of surgeons operated on patients at both hospitals. With respect to race, only the 123 patients (8.6%) categorized as African American and the 1,302 patients (91.4%) designated as white were studied.

There were no significant differences between African-American and white patients in height, weight, and body surface area. However, a striking finding was that African Americans came to mitral valve surgery at a significantly younger age (45.6 ± 14.4 versus 60.5 ± 15.3 years, p < 0.001) and were sicker in terms of risk factors (Table 1). African Americans had higher incidences of preoperative diabetes mellitus (13.0% versus 7.4%, p = 0.03), renal failure (5.7% versus 2.6%, p = 0.05), cardiomegaly (50.4% versus 35.5%, p < 0.001), current congestive heart failure (39.8% versus 31.3%, p = 0.05), previous stroke (12.2% versus 6.1%, p = 0.01), and active endocarditis (12.2% versus 4.4%, p < 0.001). In addition, African Americans were more likely to have smoked within 2 weeks preoperatively (15.2% versus 4.6%, p < 0.001). Also, African Americans had a higher incidence of rheumatic etiology for their mitral disease (16.1% versus 5.7%, p < 0.001; Table 2). In contrast, whites had higher incidences of extensive aortic atherosclerosis or calcification (8.8% versus 2.4%, p = 0.01) and degenerative mitral disease (84.6% versus 62.5%, p < 0.001; Table 2).


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  		Table 1 Preoperative Patient Characteristics for Two Patient Groups
 

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  		Table 2 Incidence of Etiologies of Mitral Valve Disease for African Americans and Whites for Patients Undergoing Mitral Valve Repair or Replacement
 
African Americans were significantly less likely to undergo mitral valve repair compared with whites (51.2% versus 66.4%, p < 0.001; Table 3). Ninety-four percent of African-American patients with rheumatic mitral disease were repaired whereas 56% of whites with rheumatic mitral disease were repaired (p < 0.001; Table 4). In contrast, white patients who had degenerative disease were more likely to have repair (67%) when compared with African Americans who had degenerative disease (43%; p < 0.001). Similarly, whites with endocarditis had a higher likelihood of repair (41% versus 13%; p < 0.05).


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  		Table 3 Prevalence of Mitral Valve Repair and Replacement for African Americans Compared With Whites
 

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  		Table 4 Prevalence of Mitral Valve Repair (MVP) for African Americans and Whites by Etiology (p < 0.001)
 
Despite the increased incidence of some risk factors among African Americans, there was no significant difference between African Americans and whites in hospital mortality (2.4% versus 5.1%, p = 0.19; Table 5). Likewise, African Americans did not differ significantly from whites in the incidences of most postoperative complications, including stroke (0.8% versus 1.7%, p = 0.46), myocardial infarction (transmural or nontransmural, 0% versus 0%), deep sternal infection (0 versus 0.5%, p = 0.42), reoperation for bleeding (4.9% versus 2.6%, p = 0.15), reoperation for second bypass operation (0% versus 0.2%, p = 0.59), heart block or pacemaker requirement (0.8% versus 1.2%, p = 0.73), sepsis or endocarditis (1.6% versus 2.5%, p = 0.53), gastrointestinal complications (0.9% versus 1.5%, p = 0.52), renal failure (0% versus 2.7%, p = 0.07), cardiac arrest (0.8% versus 0.5%, p = 0.70), postcardiotomy shock requiring mechanical support (0% versus 0.1%, p = 0.76), or respiratory failure (6.5% versus 6.8%, p = 0.91).


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  		Table 5 Hospital Mortality and Complications for African Americans Compared With Whites
 

   Comment
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
References
 
Many studies have documented disparities associated with race, particularly African-American race, in access to medical and surgical care for patients with cardiac disease [16, 17]. African Americans have been shown to be less likely to undergo cardiac catheterization and CABG when compared with whites [2]. Despite a greater incidence of risk factors for cardiac disease in the African-American population [18], disease severity does not appear to be a contributing factor whereas access to care and compliance may play roles. No individual factor has been shown to account for the differences in treatment rates.

In addition, studies comparing outcomes after CABG by race have suggested worse outcomes in African Americans compared with whites. Bridges and coworkers [1], using The Society of Thoracic Surgeons national database, found a statistically significant perioperative mortality difference between African Americans and whites of 3.83% versus 3.14%. This significant difference in mortality rate is supported by the study of Higgins and colleagues [19] (5.5% versus 2.5%), but not by the work of Gray and coinvestigators [20] (5.5% versus 4.6%). Using logistic regression analysis, Bridges and colleagues [1] and Taylor and others [21] found race to be a predictor of mortality, whereas Higgins and coworkers [19] did not. In a comprehensive review, Bridges [3] highlighted the possible influence of unrecognized risk factors not currently accounted for in multivariate risk models and how these factors might affect not only those patients undergoing CABG, but also the increasing numbers of patients undergoing valve and ventricular remodeling procedures.

In the only other study to examine specifically the relationship between race and valve surgery, Taylor and colleagues [4] used the The Society of Thoracic Surgeons national database to retrospectively review perioperative outcomes after mitral valve replacement or aortic valve replacement [4]. The results showed race was not a predictor of operative mortality after mitral valve replacement alone (5.60% for African Americans versus 6.18% for whites) or aortic valve replacement alone (4.60% for African Americans versus 3.62% for whites). For mitral valve replacement, African-American patients were significantly younger (52.9 versus 63.8 years), more commonly female (64.4% versus 58.6%), and had higher incidences of several risk factors, including active endocarditis, smoking, diabetes mellitus, obesity, renal failure, hypertension, previous stroke, congestive heart failure, low ejection fraction, and urgent operation. Whites had higher incidences of a positive family history of coronary artery disease, hypercholesterolemia, and arrhythmias.

Our results on mitral valve surgery patients are in agreement with many of Taylor’s findings. Most important, we found African Americans to present for mitral valve surgery at a significantly younger age than whites (45.6 years versus 60.5 years) and also to have higher incidences of diabetes mellitus, previous stroke, congestive heart failure, active endocarditis, and renal failure. In addition, we too found no significant difference in hospital mortality (2.4% versus 5.1%). In contrast to the findings of Taylor and coworkers, we did not detect a significant diffence in postoperative complication rates. However, this inconsistency might be due to the smaller numbers in the present study.

The present results show that when African-American patients with mitral valve disease have access to the same quality hospitals and surgeons as whites, the African-American patients have similar hospital mortality and complication rates despite a higher incidence of certain risk factors. The findings of this study also show, however, that mitral valve repair was not performed as commonly among African Americans (51.2%) as among whites (66.4%, p < 0.001). This finding might have significant longer-term implications, as patients requiring mitral valve replacement have a worse prognosis.

Surprisingly, the lower rate of valve repair among African Americans was not due to a higher incidence of rheumatic disease. Although African Americans had a higher incidence of rheumatic disease (16.1% versus 5.7%), those with rheumatic mitral valve disease had a greater likelihood of having their valve repaired compared with whites (94.4% versus 55.7%). It should be noted that among the 17 African-American patients with rheumatic etiology who underwent mitral repair, 10 patients were females of child-bearing age, which precluded the anticoagulation regimen that would be necessitated by use of mitral valve replacement. Other patients in this rheumatic subgroup were deemed unlikely to remain fully compliant with an anticoagulation regimen. It was degenerative mitral valve disease in African Americans that was less likely to be repaired compared with whites (42.8% versus 67.2%), accounting for the lower overall repair rate. In addition, endocarditis was less likely to be repaired in African Americans (13.3% versus 40.6% in white). If the lower likelihood of repair for degenerative mitral valve disease in African Americans is due to more advanced disease, encouraging earlier referral might impact the ability of surgeons to repair the valve. Whether presentation at an significantly earlier age among African Americans is a result of failures in primary care or a result of an enhanced susceptibility to the process of mitral disease and comorbidities remains to be determined.

Limitations of the Study
This was a retrospective study based on medical records. Although the percentage of African-American patients in this study (8.6%) is relatively small, it exceeds the percentage of African-American patients (5.5%) among all patients undergoing CABG in New York State from 1997 through 2000 [22]. Nevertheless, the relatively small numbers precluded the use of stratification or propensity case matching techniques. Furthermore, the power of the test might not have been sufficient to demonstrate the statistical significance of the differences in mortality and the incidence of risk factors and complications between the two groups.

In summary, the present findings suggest that African Americans present for mitral valve surgery at a significantly younger age compared with whites and with higher rates of renal failure, congestive heart failure, endocarditis, and rheumatic heart disease. Degenerative mitral valve disease is more common among whites. African Americans were overall less likely to undergo mitral valvuloplasty, a fact that might have an effect on long-term outcome. This difference was due primarily to a lower likelihood of repair for African-American patients with degenerative mitral disease and endocarditis. Improved screening of this racial group might facilitate earlier referral, increasing the potential for mitral valvuloplasty.


   References
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
 References
 

  1. Bridges CR, Edwards FH, Peterson ED, Coombs LP. The effect of race on coronary bypass operative mortality J Am Coll Cardiol 2000;36:1870-1876.[Abstract/Free Full Text]
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  3. Bridges CR. Cardiac surgery in African Americans Ann Thorac Surg 2003;76(Suppl):1356-1362.
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  6. Sand ME, Naftel DC, Blackstone EH, Kirklin JW, Karp RB. A comparison of repair and replacement for mitral valve incompetence J Thorac Cardiovasc Surg 1987;94:208-219.[Abstract]
  7. Perier P, Deloche A, Chauvaud S, et al. Comparative evaluation of mitral valve repair and replacement with Starr, Bjork, and porcine valve prostheses Circulation 1984;70(Issue 3 Suppl):II87-II92.
  8. Lawrie GM. Mitral valve repair versus replacement: current recommendations and long-term results Cardiol Clin 1998;16:437-448.[Medline]
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Invited commentary
Charles R. Bridges
Ann. Thorac. Surg. 2008 85: 93. [Extract] [Full Text] [PDF]



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Ann. Thorac. Surg., January 1, 2008; 85(1): 93 - 93.
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