ATS
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to Personal Folders
Right arrow Download to citation manager
Right arrow Author home page(s):
Roger J. F. Baskett
Gregory M. Hirsch
John A. P. Sullivan
Right arrow Permission Requests
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Baskett, R. J. F.
Right arrow Articles by Sullivan, J. A. P.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Baskett, R. J. F.
Right arrow Articles by Sullivan, J. A. P.
Related Collections
Right arrow Education

Ann Thorac Surg 2004;78:1236-1240
© 2004 The Society of Thoracic Surgeons

Original article: cardiovascular

Training Residents in Mitral Valve Surgery

Roger J. F. Baskett, MDa,*, Dimitri Kalavrouziotis, MDa, Karen J. Buth, MSa, Gregory M. Hirsch, MDa, John A. P. Sullivan, MDa

a The Maritime Heart Center, Halifax, Nova Scotia, Canada

Accepted for publication April 12, 2004.

* Address reprint requests to Dr Baskett, The Maritime Heart Center, Room 2269, 1796 Summer St, Halifax, Nova Scotia, Canada B3H 3A7
rogerbaskett{at}hotmail.com


   Abstract
Top
 Abstract
Introduction
 Patients and Methods
 Results
 Comment
 References
 
BACKGROUND: The safety of training residents in complex procedures has not been elucidated. In particular, the impact of resident-performed mitral valve surgery on patient outcomes is unknown.

METHODS: All mitral valve procedures performed by residents between 1998 and 2003 were compared with those performed by staff surgeons. Operative mortality and a composite morbidity (reoperation for bleeding, myocardial infarction, infection, stroke, or ventilation > 24 hours) were compared using multivariate analysis. Individual outcomes were compared with the use of propensity scores.

RESULTS: There were 1020 cardiac surgeries performed by residents, including 165 mitral valve procedures (86 replacements, 79 repairs). In the same period, the staff surgeons performed 261 mitral procedures. Crude operative mortality for isolated mitral procedures was 5.4% and 4.7% (resident and staff, respectively, p = 1.00). Mitral valve repair including combined procedures had an operative mortality of 3.8% and 4.3% (resident and staff, respectively, p = 1.00). The composite morbidity outcome was 29.7% and 35.3% for resident and staff-performed cases, respectively (p = 0.24). In multivariate analysis, resident was not associated with the adverse outcomes examined (OR 0.80, 95% CI, 0.47, 1.37). The incidence of major adverse outcomes for propensity score-matched mitral valve cases, including combined procedures, were similar between residents and staff, respectively: mortality, 7.4% versus 8.7% (p = 0.67), stroke, 4.0% versus 6.7% (p = 0.30), and reoperation for bleeding, 4.7% versus 9.4% (p = 0.11).

CONCLUSIONS: There were no significant differences in morbidity and mortality in patients undergoing mitral valve surgery between resident and staff surgeons. It is possible to train residents to perform complex cardiac cases without adversely affecting outcomes.


   Introduction
Top
 Abstract
 Introduction
Patients and Methods
 Results
 Comment
 References
 
Concern has been raised about the safety of training surgeons in the performance of complex cardiac procedures, particularly mitral valve repair [1]. Furthermore, it has been demonstrated that the proportion of valves repaired or replaced correlates with the number of valve procedures performed each year by an individual surgeon [2]. The relationship between volume of cases and outcome has also been well established, both for individual surgeon and institution [3]. In light of enhanced efforts to scrutinize and improve patient outcomes, there may be a resultant loss of direct surgical experience for surgeons-in-training [4].

The safety of training residents in cardiac surgery has rarely been studied. We have demonstrated that it is safe to allow even quite junior residents to perform coronary artery bypass grafting (CABG) and aortic valve replacement [5]. The only study of residents in valve surgery is more than 20 years old, and looked only at isolated valve replacement [6, 7]. In these studies and in most others, residents performed only lower risk cases, the vast majority of which were isolated first-time CABG; high-risk cases were excluded or not reported [4, 8–10]. The safety of resident-performed complex cardiac surgical cases is unknown.

Our objective was to assess the safety of training residents to perform mitral valve procedures in terms of in-hospital morbidity and mortality.


   Patients and Methods
Top
 Abstract
 Introduction
 Patients and Methods
Results
 Comment
 References
 
All cases involving a mitral valve procedure (either isolated or in combination with other valve or coronary surgery) between January 1998 and May 2003 were included in the study. All patient data were collected prospectively using our Maritime Heart Center database [5]. The database captures 100% of cases and is validated annually by auditing a random sample of 10% of patient charts. At our last audit, less than 5% of data forms contained random errors, and no systematic errors were found. The missing data points in the database are less than 5%.

A resident database was established and the individual residents were responsible for keeping track of their own cases. A resident case was defined as a case in which the resident performed the entire surgical procedure with the staff surgeon acting as an assistant or supervising while another person directly assisted the resident. If the staff surgeon was assisting they stood on the assistant's side of the table and would, from time to time, assess the progress by looking over from that side or coming around to the surgeon's side to look. The resident-performed cases were selected by the residents. The actual selection of resident cases is based on the cases booked each day. The resident (there is only one senior resident at a time) has the choice of the cases they would like to do of those booked for a given day. All patients underwent intraoperative transesophageal echocardiography. No mitral valve repair was accepted with more than trivial to 1+ mitral insufficiency.

In the Canadian system, residents may begin the 6-year cardiac surgery-training program directly from medical school. After 2.5 years of core surgery and cardiology training, the resident spends 6 months as a junior and 12 months as a senior (a sixth-year resident) on the adult cardiac surgery service. The cases presented here include the cumulative experience of 3 residents: 2 junior 6-month rotations, and 36 months of senior rotations (3 residents).

The primary outcome of interest was in-hospital mortality. In the interest of looking at several morbidity outcomes, and to increase statistical power, a composite morbidity consisting of any one of the following variables was used: reoperation for bleeding, reoperation related to the newly repaired or replaced mitral valve, any wound infection, permanent stroke, myocardial infarction, or ventilation more than 24 hours. The Society of Thoracic Surgeons definitions were used for all variables and outcomes [11]. Preoperative and intraoperative variables and patient outcomes were compared using {chi}2 and t tests.

In order to assess the independent effect of resident as surgeon on patient outcomes a backward logistic regression model was constructed for the composite outcome of in-hospital mortality or the combined morbidity outcome The model was assessed using the receiver operating characteristic (ROC) and goodness of fit (GOF). In addition, a full logistic regression model was used to calculate individual surgeon (only staff, who performed at least 25 procedures, were included) and resident (the three residents combined as a single surgeon) observed-to-expected ratios for the outcome [12, 13]. These were displayed graphically with 95% confidence intervals (95% CI) to assess the variability among surgeons and the residents. Cardiopulmonary bypass and aortic cross-clamp times are expressed as median values with the interquartile range in parentheses.

To allow for a multivariate comparison of the individual morbidity outcomes, the resident and staff cases were compared using propensity score analysis. This technique reduces the many covariates to a single variable and facilitates a comparison of groups that may be otherwise quite disparate [14]. The propensity score is a measure of the likelihood of a patient receiving an intervention (resident performing the case). Patients with similar propensity scores will have similar characteristics, and thus should differ only according to the intervention in question. Therefore, the outcome of interest can be compared for those that did and did not receive the intervention (resident doing the procedure). The technique is well described and used in cardiac surgical literature [15, 16].

Briefly, a nonparsimonious logistic regression model was created to predict a resident case. The resident cases were then matched one to one to staff surgeon cases based on the individual propensity scores using the "greedy matching" technique [17]. This creates two groups that are very similar for all the covariates and differ only for the "intervention" of interest in this case who performed the surgery.


   Results
Top
 Abstract
 Introduction
 Patients and Methods
 Results
Comment
 References
 
There were a total of 6453 cardiac surgical cases between January 1998 and May 2003. The three residents performed 1020 of these cases. One hundred sixty-five of the resident cases included a mitral valve procedure, 56% of which were isolated mitral valve procedures. Over the same period, 261 mitral valve procedures were performed by the staff surgeons, 49% of which were isolated mitral valve procedures. Preoperative patient characteristics were similar between the resident and staff cases. There were slightly more reoperative cases and patients with chronic obstructive pulmonary disease (COPD) among the resident-performed cases; staff cases had more preoperative renal insufficiency (Table 1) . The etiology of mitral valve disease and the procedures performed were also similar (Table 2). However, resident cases involved a higher proportion of anterior leaflet repairs, whereas staff cases involved a higher proportion of isolated annuloplasty procedures (Table 2). There were no significant differences in mortality between resident and staff mitral valve cases, including combined procedures (7.9% vs 8.1%, respectively, p = 0.95). The mortality associated with isolated mitral valve cases was not different between residents and staff, respectively: 5.4% and 4.7% (p = 1.00). Similarly, there was no significant difference in morbidity between resident and staff performed cases (Table 3). For patients undergoing mitral valve repair, with or without CABG or other valve procedure, mortality was 3.8% and 4.3% (resident and staff, respectively, p = 1.00) (Table 3).


View this table:
[in this window]
[in a new window]
  		Table 1. Comparison of Resident and Staff Mitral Valve Patients

 

View this table:
[in this window]
[in a new window]
  		Table 2. Comparison of Resident and Staff Mitral Valve Cases

 

View this table:
[in this window]
[in a new window]
  		Table 3. Crude Morbidity and Mortality in Resident and Staff Mitral Valve Patients

 
In multivariate analysis, resident-performed procedure was not associated with the composite outcome (mortality or any of the following morbidities: reoperation for bleeding or valve, any wound infection, permanent stroke, myocardial infarction, or ventilation > 24 hours; OR 0.80, 95% CI, 0.47, 1.37). The variables associated with mortality and morbidity were: ischemic mitral valve pathology (OR 3.18, 95% CI, 1.07, 9.47), preoperative renal insufficiency (OR 3.73, 95% CI, 1.62, 8.64), and cardiogenic shock (OR 7.63, 95% CI, 1.90, 30.70). The model has an ROC of 0.82. For both morbidity and mortality, the results for the residents (considered as a single surgeon) fall well within the range of results for individual staff surgeons (Fig 1).



View larger version (14K):
[in this window]
[in a new window]
  		Fig 1. All mitral valve cases combined morbidity and mortality observed-to-expected (O/E) ratios for the residents as a group (represented by the topmost horizontal bar) and each of the individual staff surgeons who performed greater than 25 mitral valve procedures during the study period (represented by the five inferior horizontal bars). Each dot and horizontal bar displays the point estimate for the O/E ratio and the 95% confidence intervals, respectively. The expected composite outcome, mortality or composite morbidity (reoperation for bleeding or valvular problems, wound infection, permanent stroke, perioperative myocardial infarction, ventilation > 24 hours) is calculated for each surgeon's patients based on the coefficients from the logistic regression model for composite morbidity.

 
In order to compare individual outcomes with multivariate techniques, we used propensity score matching to account for differences between resident and staff cases. Using the propensity scores generated for each patient we were able to match 149 of the 165 resident cases one to one to staff cases of similar risk (Table 4). There were no statistically significant differences between resident and staff surgeons for any of the outcomes examined (Table 5). In addition, median cardiopulmonary bypass times for resident and staff-performed cases, respectively, were similar (155 minutes [range 118–205 minutes] and 168 minutes [range 124–215 minutes], p = 0.16), as were median aortic cross-clamp times (117 minutes [range 87–147 minutes] and 117 minutes [range 90–149 minutes] of resident and staff, respectively, p = 0.65).


View this table:
[in this window]
[in a new window]
  		Table 4. Comparison of Propensity Score-Matched Resident and Staff Mitral Patients

 

View this table:
[in this window]
[in a new window]
  		Table 5. Morbidity and Mortality in Propensity Score-Matched Resident and Staff Mitral Valve Patients

 

   Comment
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
References
 
This study has demonstrated that mitral valve cases can be performed by residents under staff supervision with good results, and comparable morbidity and mortality, to those performed by the staff. In particular, the incidence of mortality for all mitral valve cases, including combined procedures, is 7.9% and 8.1% and that of stroke is 3.6% and 6.1% (resident and staff, respectively). In addition there were no significant differences in morbidity between resident and staff-performed cases. The duration of cardiopulmonary bypass and cross-clamp times were not significantly different between the two groups. The cases performed by the residents were of comparable risk to those of the staff surgeons. The residents performed a slightly greater variety of mitral valve repair procedures, with fewer isolated annuloplasties and more anterior leaflet repairs.

Several limitations in this study are worthy of note. Sample size limits our ability to assert the null hypothesis. Nevertheless, we report a nonsignificant trend toward lower morbidity and mortality associated with the resident-performed procedures. In addition, these results reflect the practice in our center and may not apply elsewhere. This study also lacks long-term data. Review of patient outcomes at time points after hospital discharge, particularly for the mitral valve repair cases, will be important. Nevertheless, in terms of in-hospital morbidity and mortality there are no apparent adverse effects associated with allowing residents to perform mitral valve surgery under staff supervision.

We have demonstrated that patient outcomes are not adversely affected when the resident acts as the surgeon. These findings are consistent with those of Sethi and coworkers [6, 7] that demonstrated the safety of trainee-performed isolated valve replacement. However, others have reported that residents are usually delegated the low-risk patients [4, 8, 9]. Resident-performed mitral valve procedures in this study were not different in risk of adverse patient outcomes than staff-performed mitral valve procedures, and in-hospital morbidity and mortality were not different in the resident-performed cases. Our data indicate that residents as primary operators during complex mitral valve procedures are not associated with prolonged operative times or adverse patient outcomes. Surgeons-in-training may be unnecessarily denied the opportunity of performing complex cases under direct supervision of experienced staff surgeons, forcing them to defer the performance of these cases to their first years of independent practice, likely without expert supervision.

Frater has stated that few surgeons will have the chance to be properly trained in mitral valve surgery and thus must train themselves after being "properly prepared" [1]. The belief held by some staff surgeons is that residents cannot be allowed to perform such complex procedures as mitral valve repair or double-valve cases, bringing into question the goals and quality of cardiac surgical training programs. In our program, a resident will perform, on average, more than 50 mitral valve procedures during their training. Nearly half of these cases include concomitant CABG or other procedures, and roughly half of the cases were mitral valve repairs (Table 2).

The exact number of cases of a given procedure required to achieve competence is unknown, and clearly differs from surgeon to surgeon. It has been suggested that 50 cases would be adequate to train a resident in off-pump coronary surgery; while fewer cases have been suggested by others [18, 19]. Given the volume of mitral valve procedures in our institution (100 to 120/year of 1200 total cardiac cases), the senior cardiac resident should easily be able to do half to two-thirds of those cases under the guidance of experienced staff.

Many centers appear to be entrenched with the belief that complex mitral valve procedures are too difficult for residents to perform under supervision. It has been asserted that this practice is not a matter of safety but one of philosophy [20]. A learning curve clearly exists over the course of a surgeon's career [21]. Caputo and associates [22] have recently demonstrated that it is possible to increase trainee exposure even to new techniques. The current study adds further evidence to the contention that it is safe to properly train residents in cardiac surgery including complex procedures.


   References
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
 References
 

  1. Frater R. Assumptions and realities of mitral valve repair. J Heart Valve Dis. 2003;12:11–13[Medline]
  2. Northrup W, Kshettry V, Dubois K. Trends in mitral valve surgery in a large multi-surgeon multi-hospital practice, 1979–1999. J Heart Valve Dis. 2003;12:14–24[Medline]
  3. Hannan E, O'Donnell J, Kilburn H, Bernard H, Yazici A. Investigation of the relationship between volume and mortality for surgical procedures performed in New York State hospitals. JAMA. 1989;262:503–510[Abstract/Free Full Text]
  4. Jenkins D, Valencia O, Smith E. Risk stratification for training in cardiac surgery. J Thorac Cardiovasc Surg. 2001;49:75–77
  5. Baskett R, Buth K, Legare J, et al. Is it safe to train residents to perform cardiac surgery? Ann Thorac Surg. 2002;74:1043–1049[Abstract/Free Full Text]
  6. Sethi G, Oprian C, Miller C, et al. Operative mortality in patients undergoing single valve replacement in teaching institutions–early mortality as a function of resident versus staff. Surgery. 1988;104:301–310[Medline]
  7. Sethi G, Hammermeister K, Oprian C, et al. Impact of resident training on postoperative morbidity in patients undergoing single valve replacement. J Thorac Cardiovasc Surg. 1991;101:1053–1059[Abstract]
  8. Anderson J, Parker D, Unsworth-White M, Treasure T, Valencia O. Training surgeons and safeguarding patients. Ann R Coll Surg Engl. 1996;78(Suppl 3):116–118[Medline]
  9. Caputo M, Chamberlain M, Ozalp F, Underwood M, Ciulli F, Angelini G. Off-pump coronary operations can be safely taught to cardiothoracic trainees. Ann Thorac Surg. 2001;71:1215–1219[Abstract/Free Full Text]
  10. Goodwin A, Birdi I, Ramesh T. Effect of surgical training on outcome and hospital costs in coronary surgery. Heart. 2001;85:454–457[Abstract/Free Full Text]
  11. Shroyer L, Plomondon M, Grover F, Edwards F. The 1996 coronary artery bypass risk model: The Society of Thoracic Surgeons Adult Cardiac National Database. Ann Thorac Surg. 1999;:67 1205–8
  12. Hosmer D, Lemeshow S. Applied logistic regression. New York: John Wiley and Sons Inc.; 1989.
  13. Lemeshow S, Hosmer DW. A review of goodness of fit statistics for use in the development of logistic regression models. Am J Epidemiol 1982;115:92–106
  14. Rosenbaum P, Rubin D. The central role of the propensity score in observational studies for causal effects. Biometrika. 1983;70:41–55[Abstract/Free Full Text]
  15. Normand SL, Landrum MB, Guadagnoli E, et al. Validating recommendations for coronary angiography following acute myocardial infarction in the elderly: a matched analysis using propensity scores. J Clin Epidemiol. 2001;54:387–398[Medline]
  16. Blackstone EH. Comparing apples and oranges. J Thorac Cardiovasc Surg. 2002;123:8–15[Free Full Text]
  17. Parsons L. Reducing bias in a propensity matched-pair sample using greedy matching techniques. In Proceedings of the twenty-sixth annual SAS users group international conference. Cary, NC: SAS Institute Inc., 2001;214–26
  18. Karamanoukian H, Panos A, Bergsland J, Salerno T. Perspective of a cardiac surgery resident in-training on off-pump coronary bypass operation. Ann Thorac Surg. 2000;69:42–45[Abstract/Free Full Text]
  19. Kron I. Invited commentary. Ann Thorac Surg. 2000;69:45[Free Full Text]
  20. Hargreaves D. A training culture in surgery. BMJ. 1996;313:1635–1639[Free Full Text]
  21. Novick R, Stitt L. The learning curve of an academic cardiac surgeon: use of the CUSUM method. J Card Surg. 1999;14:312–322[Medline]
  22. Caputo M, Bryan A, Capoun R, et al. The evolution of training in off-pump coronary surgery in a single institution. Ann Thorac Surg. 2002;74:S1403–1407[Abstract/Free Full Text]



This article has been cited by other articles:


Home page
 ICVTSHome page
D. H. Freed, A. J. Drain, J. Kitcat, M. T. Jones, and S. A.M. Nashef
Death in low-risk cardiac surgery: the failure to achieve a satisfactory cardiac outcome (FIASCO) study
Interactive CardioVascular and Thoracic Surgery, October 1, 2009; 9(4): 623 - 625.
[Abstract] [Full Text] [PDF]

Home page
 Ann. Thorac. Surg.Home page
F. G. Bakaeen, A. S. Dhaliwal, D. Chu, B. Bozkurt, P. Tsai, S. A. LeMaire, M. J. Wall Jr, J. S. Coselli, and J. Huh
Does the Level of Experience of Residents Affect Outcomes of Coronary Artery Bypass Surgery?
Ann. Thorac. Surg., April 1, 2009; 87(4): 1127 - 1134.
[Abstract] [Full Text] [PDF]

Home page
 CirculationHome page
S. C. Stoica, D. Kalavrouziotis, B.-J. Martin, K. J. Buth, G. M. Hirsch, J. A. Sullivan, and R. J.F. Baskett
Long-Term Results of Heart Operations Performed by Surgeons-in-Training
Circulation, September 30, 2008; 118(14_suppl_1): S1 - S6.
[Abstract] [Full Text] [PDF]

Home page
 BMJHome page
T. P Grantcharov and R. K Reznick
Teaching procedural skills
BMJ, May 17, 2008; 336(7653): 1129 - 1131.
[Full Text] [PDF]

Home page
 J. Thorac. Cardiovasc. Surg.Home page
P. C. Austin
Propensity-score matching in the cardiovascular surgery literature from 2004 to 2006: a systematic review and suggestions for improvement.
J. Thorac. Cardiovasc. Surg., November 1, 2007; 134(5): 1128 - 1135.
[Abstract] [Full Text] [PDF]

Home page
 ICVTSHome page
A. Karagounis, G. Asimakopoulos, G. Niranjan, O. Valencia, and V. Chandrasekaran
Complex off-pump coronary artery bypass surgery can be safely taught to cardiothoracic trainees
Interactive CardioVascular and Thoracic Surgery, June 1, 2006; 5(3): 222 - 226.
[Abstract] [Full Text] [PDF]

Home page
 Ann. Thorac. Surg.Home page
G. Asimakopoulos, A. P. Karagounis, O. Valencia, D. Rose, G. Niranjan, and V. Chandrasekaran
How Safe Is It to Train Residents to Perform Off-Pump Coronary Artery Bypass Surgery?
Ann. Thorac. Surg., February 1, 2006; 81(2): 568 - 572.
[Abstract] [Full Text] [PDF]

Home page
 Ann. Thorac. Surg.Home page
C. Alexiou, G. Doukas, M. Oc, B. Oc, L. Hadjinikolaou, and T. J. Spyt
Effect of Training in Mitral Valve Repair Surgery on the Early and Late Outcome
Ann. Thorac. Surg., July 1, 2005; 80(1): 183 - 188.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to Personal Folders
Right arrow Download to citation manager
Right arrow Author home page(s):
Roger J. F. Baskett
Gregory M. Hirsch
John A. P. Sullivan
Right arrow Permission Requests
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Baskett, R. J. F.
Right arrow Articles by Sullivan, J. A. P.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Baskett, R. J. F.
Right arrow Articles by Sullivan, J. A. P.
Related Collections
Right arrow Education

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
ANN THORAC SURG ASIAN CARDIOVASC THORAC ANN EUR J CARDIOTHORAC SURG
J THORAC CARDIOVASC SURG ICVTS ALL CTSNet JOURNALS