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Original Articles: Adult Cardiac

Utilization and Outcomes of Unprotected Left Main Coronary Artery Stenting and Coronary Artery Bypass Graft Surgery

^a University at Albany, State University of New York, Albany, New York
^b St. Joseph's Hospital, Syracuse, New York
^c Brigham and Women's Hospital, Boston, Massachusetts

Accepted for publication May 21, 2008.

^_* Address correspondence to Dr Wu, Department of Public Health Sciences, Penn State University College of Medicine, 600 Centerview Dr, Suite 2200, A210, Hershey, PA 17033 (Email: chuntao.wu{at}psu.edu).

Dr Faxon discloses that he has a financial relationship with Boston Scientific and Johnson & Johnson.

 

	Abstract

Top Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Background: Limited contemporary information is available on outcomes for patients with unprotected left main coronary artery (LMCA) disease who are revascularized.

Methods: We examined the relative frequency, severity of illness, and outcomes of stenting and coronary artery bypass graft (CABG) surgery for treating unprotected LMCA disease in New York between January 1, 2000 and December 31, 2004. A total of 16,336 (98.7%) patients who underwent CABG surgery and 212 (1.3%) who underwent stenting were included in this study.

Results: Stent patients had higher preprocedural severity of illness (eg, they were older, more likely to be female, and had more comorbidities). A total of 135 stent patients were matched to 135 CABG patients on baseline characteristics identified by a propensity model as predictors of type of procedure received. At the end of follow-up on December 31, 2004, the respective 2-year survival rates were 94.1% and 82.0% (hazard ratio = 0.32, p = 0.005) for the 135 pairs of matched CABG and stent patients. The respective 2-year rates for freedom from subsequent revascularization were 93.7% and 62.7% (hazard ratio = 0.15, p < 0.001). In the drug-eluting stent era between October 1, 2003 and December 31, 2004, the same trends in mortality (hazard ratio = 0.73, p = 0.69) and repeat revascularization (hazard ratio = 0.10, p = 0.03) were observed among the 56 pairs of matched CABG and drug-eluting stent patients.

Conclusions: Most patients with LMCA disease who needed coronary revascularization received CABG surgery; stent patients were sicker. This study found that surgery patients experienced lower risk of long-term death and repeat revascularization. However, more studies comparing these procedures are needed, especially in the drug-eluting stent era.

For patients with unprotected left main coronary disease, coronary artery bypass graft (CABG) surgery is recommended when revascularization is needed according to the latest guidelines of the American College of Cardiology and American Heart Association [1, 2]. These recommendations are largely based upon studies conducted in the 1970s and 1980s. However, recent improvement in outcomes for left main percutaneous coronary intervention (PCI) by the use of bare-metal stents and drug-eluting stents has led to studies comparing the outcomes of left main PCI with CABG surgery [3–12]. Three single-center observational studies [13–15] and a small-scale randomized trial [16] have recently found no differences in intermediate-term mortality between the two treatments, despite inconsistent findings regarding differences in composite outcomes (major adverse cardiac and cerebrovascular events). Such studies have prompted examining whether it is time to replace CABG surgery by stenting when treating unprotected left main coronary disease [17, 18]. Consequently, more studies are needed to compare utilization and long-term outcomes of these two treatments, especially in population-based settings. In this study, we examined the differences in utilization, patient severity of illness, and long-term mortality and subsequent revascularization rates between unprotected left main coronary stenting and CABG surgery in patients who underwent procedures in New York State between January 1, 2000 and December 31, 2004.

	Material and Methods

Top Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Databases and Patient Population
Patients in this study were identified using the New York State Cardiac Surgery Reporting System (CSRS) and Percutaneous Coronary Intervention Reporting System (PCIRS). The CSRS and PCIRS are population-based registries that have been in place since 1989 and 1991, respectively. These two registries collect detailed information on patients' demographic characteristics, preprocedural risk factors, procedural information, postprocedural complications, and discharge status for all cardiac procedures and PCIs performed in nonfederal hospitals in New York State. Completeness and accuracy of the registries are assured by extensive periodic auditing.

The study population consisted of patients with left main coronary artery disease (stenosis 50%) who underwent isolated CABG surgery without other major cardiac procedures, or who underwent stent placements in the left main coronary artery and were discharged between January 1, 2000 and December 31, 2004 in New York State. Patients were excluded if they had a previous revascularization (4,139 cases), had a myocardial infarction within 24 hours prior to the procedure (420 cases), or were not residents of New York State (704 cases). A total of 16,336 CABG cases and 212 stenting cases were included in this study and were followed until December 31, 2004.

Outcomes
The main outcome measures in this study were long-term survival and freedom from subsequent revascularization (CABG surgery or PCI) after the index procedure. Short-term mortality, defined as in-hospital death or death within 30 days of procedures (in-hospital/30-day mortality), was also examined. Deaths after discharge were identified by linking patients' Social Security numbers to the Vital Statistics Death File maintained by the New York State Department of Health; subsequent revascularizations were ascertained using the CSRS and PCIRS registries.

Statistical Analysis
Differences between CABG and stent patients in baseline characteristics were compared. Patient characteristics included age, race/ethnicity, sex, size of body surface area, ejection fraction, diseased vessels, hemodynamic state, and a variety of comorbidities (history of myocardial infarction, cerebrovascular disease, peripheral arterial disease, congestive heart failure, malignant ventricular arrhythmia, chronic obstructive pulmonary disease, diabetes, and renal failure). The CSRS-CABG risk score [19] and the PCIRS risk score [20] were also used to describe patients' overall baseline risks. The ² and Fisher exact tests were applied when comparing categoric variables; and the Student t tests were used to compare means of continuous variables.

To minimize the impact of selection bias when comparing the relative benefits of left main stenting and CABG surgery, a propensity model was developed by fitting a logistic regression model with type of treatment as the dependent variable and using stepwise backward selection to identify patient baseline characteristics that were significant predictors of type of treatment [21, 22]. Patients were matched exactly on predictors of choice of treatment from the propensity model and on the time period before or after the drug-eluting stent era between October 1, 2003 and December 31, 2004. This time period was selected to avoid the period shortly after the introduction of drug-eluting stents in April 2003. When a case could be matched to more than one case in another treatment group, the pair with the earliest and closest procedure dates was selected. Patients who could not be matched were eliminated for this part of the analysis.

The difference between the two types of treatment in in-hospital/30-day mortality for matched patients was then examined using the Fisher exact test. Kaplan-Meier curves were created and hazard ratios were calculated using Cox proportional hazard models (with type of treatment as the single independent variable) to compare longer-term survival and long term need for repeat revascularization for the two types of treatment for matched patients [23]. Patients who died before December 31, 2004 without any repeat revascularizations were treated as censored data in this set of analyses. All analyses were conducted using SAS 9.1 (SAS Institute, Cary, NC), and the significance of all statistical tests were determined at 0.05 two-sided confidence level.

	Results

Top Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
As noted above, a total of 16,336 patients (98.7%) underwent CABG surgery and 212 patients (1.3%) underwent stenting. The annual number of patients treated with CABG surgery for left main coronary artery disease decreased from 3,460 in 2000 to 3,081 in 2004; on the other hand, the number of patients undergoing stenting increased from 32 in 2000 to 82 in 2004.

Table 1 describes the distributions of baseline characteristics of CABG and stent cases. Patients undergoing stenting were older, more likely to be female, had smaller body surface areas, lower ejection fractions, more extensive stenosis in the left main coronary artery, were more likely to have been hemodynamically unstable or in shock, and more likely to have had congestive heart failure. They were also less likely to have had 3 diseased vessels, to have had recent myocardial infarction prior to the index procedure, to have had cerebrovascular disease, chronic obstructive pulmonary disease, and diabetes. The average CSRS-CABG and PCIRS risk scores of the stent patients were both about 1 unit higher than the CABG cases.

As noted in the Material and Methods section, patients were then matched on the basis of patient characteristics that were significant predictors of type of procedure received in the propensity analysis in order to compare outcomes in a more equitable manner. A propensity logistic regression model identified predictors of type of procedure received as age, sex, ejection fraction, degree of stenosis of left main coronary artery, number of vessels diseased, history of myocardial infarction, cerebrovascular disease, hemodynamic state, congestive heart failure, and chronic obstructive pulmonary disease.

Using the predictors in the propensity model and the time period (before and after drug-eluting stent era) as matching criteria, a total of 135 (64%) stenting cases were matched to the same number of CABG surgery cases. Matching made the two treatment groups more comparable than the unmatched data. As noted in Table 2, there were no significant differences between CABG surgery and stent patients with regard to any of the patient risk factors in the database. The average CSRS-CABG risk scores were 3.1 for both groups; the average PCIRS risk scores were 7.8 and 7.7 for the CABG and PCI groups, respectively.

There were 3 (2.22%) in-hospital/30-day deaths in the matched CABG surgery group and 7 (5.19%) deaths in the matched stenting group (p = 0.33). Table 3 presents hazard ratios comparing CABG surgery with stenting for long-term mortality and risk of subsequent revascularization in matched patients. A total of 8 (5.93%) CABG patients and 23 (17.04%) stent patients died during the follow-up period between January 1, 2000 and December 31, 2004. The risk of dying after the index procedure during the study period was 68% lower for CABG patients than for stent patients after controlling for baseline risk factors (hazard ratio = 0.32, 95% confidence interval (CI): 0.14 to 0.71, p = 0.005). The 2-year survival rate was 94.1% and 82.0% for CABG surgery and stenting, respectively (p = 0.003; Fig 1).

View larger version (5K): [in this window] [in a new window]   Fig 1. Survival curves for coronary artery bypass grafting (CABG) surgery and stent patients with left main coronary artery disease who were matched on the basis of significant predictors of type of intervention.

View larger version (7K): [in this window] [in a new window]   Fig 2. Survival curves for freedom from subsequent revascularization for coronary artery bypass grafting (CABG) surgery and stent patients with left main coronary artery disease who were matched on the basis of significant predictors of type of intervention.

	Comment

Top Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
In this study we examined the frequency of use of alternative interventions (ie, CABG surgery and stenting) for patients with unprotected left main coronary artery disease in New York State between January 1, 2000 and December 31, 2004. We compared patient profiles for the two interventions and examined short- and long-term survival and the need of repeat revascularization after index procedures.

Recent studies in the literature have reported frequent utilization of stenting for left main disease patients [13–15]. For example, the study by Chieffo and colleagues [13] included 107 drug-eluting stent and 142 CABG surgery cases between March 2002 and July 2004; the study by Lee and colleagues [14] included 50 drug-eluting stent and 123 CABG surgery cases since April 2003; and the study by Palmerini and colleagues [15] included 63 bare-metal stent patients, 94 drug-eluting stent patients, and 154 CABG surgery cases from January 2002 to June 2005. In contrast, in our study, 98.7% of the patients who qualified for the study (no previous revascularization, myocardial infarction within 24 hours prior to the procedure, or non-New York State residents) underwent CABG surgery. It is evident that the utilization of left main stenting in previous studies was quite different from our population-based study in New York State. In summary, we found that relatively few patients with left main disease who are not primary angioplasty patients undergo stenting, although there was a slight tendency toward higher stenting rates over time.

With regard to preprocedural severity of illness, we found that the left main disease patients who did undergo stenting were sicker than their CABG surgery counterparts. Patients undergoing stenting had higher CSRS-CABG and PCIRS risk scores and were older, more likely to be female, had smaller body surface areas, lower ejection fractions, more extensive stenosis in the left main coronary artery, were more likely to have been hemodynamically unstable or in shock, and more likely to have had congestive heart failure. Thus, stenting appeared to have been used for patients who were regarded as contraindicated or at least dangerous risks for surgery.

With respect to differences in outcomes, we found that CABG surgery was associated with a significantly lower risk of long-term mortality (hazard ratio = 0.32, p = 0.005) and subsequent revascularization (hazard ratio= 0.15, p < 0.001) in 135 matched pairs of patients treated between January 1, 200 and December 31, 2004. In the drug-eluting stent era between October 1, 2003 and December 31, 2004, the same trend of advantage in survival for CABG surgery was also present, but the difference was not statistically significant among 56 matched pairs of patients (hazard ratio = 0.73, p = 0.69), probably due to the small sample size and short length of follow-up. Nonetheless, CABG surgery had a lower risk of repeat revascularization (hazard ratio = 0.10, p = 0.03) compared with drug-eluting stents.

The results of our study on the relative benefit of left main stenting and CABG surgery in the drug-eluting stent era were consistent with 4 other studies [13–16] comparing left main coronary artery stenting and CABG surgery, all of which found differences in longer term survival between the two procedures were not statistically significant. However, similar to the other 4 studies, the small sample size of drug-eluting stent patients (50 to 107 patients) and short length of follow-up may limit statistical power to detect differences in mortality after left main stenting and CABG surgery. Therefore, studies with greater sample sizes and longer lengths of follow-up are needed to compare the relative long-term survival of left main stenting with drug-eluting stents and CABG surgery.

But, it should be noted that when the bare-metal stents and the drug-eluting stents patients were pooled together to have a larger sample size and were compared with the CABG surgery patients, those who received CABG surgery had experienced higher 2-year survival (94.1% for CABG vs 82.0% for stenting, p = 0.003). This finding is of significance even in the drug-eluting stent era because the utilization of drug-eluting stents has declined recently; on the other hand, the use of bare-metal stents has increased.

It should be noted that, as in the 3 studies mentioned above [13–15], our study was an observational study and the findings may be subject to selection bias. What was unique in our study is that we matched stent and CABG surgery cases exactly on predictors of type of procedure received to control the impact of selection bias. However, unlike randomized clinical trials, unmeasured risk factors related to choice of treatment and long-term outcomes cannot be controlled in an observational study. For instance, we had no access to detailed angiographic information such as the location of the left main stenosis (eg, ostial or body versus bifurcation). In addition, although noncardiovascular comorbidities such as chronic obstructive pulmonary disease and renal failure were examined as candidate predicators for type of surgery received in this study, other life threatening rare conditions (eg, cancer) were not available in the New York State PCIRS and CSRS data. It is possible that such conditions could be the reason why stenting was chosen for a patient.

Another caveat is that patients who moved out of New York after their index procedures could not be tracked. A previous analysis comparing Medicare data to New York State PCIRS and CSRS data showed that the number of out-of-state deaths lost was minimal and was not found to be different between types of treatments [24].

In summary, this study adds more data to be considered in the evidence-based decision making process. Indeed, as was pointed out elsewhere, more studies in this area are necessary in consideration of expanding the practice of left main stenting [17, 18, 25]. The ongoing SYNTAX trial, a multicenter randomized trial comparing CABG surgery and drug-eluting stenting in patients with 3-vessel disease and left main coronary artery disease should provide important information in this regard [26].

	Acknowledgments

Top Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
The authors would like to thank Kenneth Shine, MD, the Chair of New York State's Cardiac Advisory Committee (CAC), and the remainder of the CAC for their encouragement and support of this study; and Paula Waselauskas, Kimberly Cozzens, Rosemary Lombardo, Cynthia Johnson and the cardiac surgery departments and cardiac catheterization laboratories of the participating hospitals for their tireless efforts to ensure the timeliness, completeness, and accuracy of the registry data.

	References

Top Abstract Introduction Material and Methods Results Comment Acknowledgments References

 

1. Eagle KA, Guyton RA, Davidoff R, et al. ACC/AHA 2004 guideline update for coronary artery bypass graft surgery: Summary article. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (committee to update the 1999 guidelines for coronary artery bypass graft surgery). Circulation 2004;110:1168-1176.[Free Full Text]
2. Smith Jr SC, Feldman TE, Hirshfeld Jr JW, et al. ACC/AHA/SCAI 2005 Guideline Update for Percutaneous Coronary Intervention - Summary article: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/SCAI Writing Committee to Update the 2001 Guidelines for Percutaneous Coronary Intervention) Circulation 2006;113:156-175.[Free Full Text]
3. Silvestri M, Barragan P, Sainsous J, et al. Unprotected left main coronary artery stenting: immediate and medium- term outcomes of 140 elective procedures J Am Coll Cardiol 2000;35:1543-1550.[Abstract/Free Full Text]
4. Black A, Cortina R, Bossi I, Choussat R, Fajadet J, Marco J. Unprotected left main coronary artery stenting: Correlates of midterm survival and impact of patient selection J Am Coll Cardiol 2001;37:832-838.[Abstract/Free Full Text]
5. Tan WA, Tamai H, Park SJ, et al. Long-term clinical outcomes after unprotected left main trunk percutaneous revascularization in 279 patients Circulation 2001;104:1609-1614.[Abstract/Free Full Text]
6. Takagi T, Stankovic G, Finci L, et al. Results and long-term predictors of adverse clinical events after elective percutaneous interventions on unprotected left main coronary artery Circulation 2002;106:698-702.[Abstract/Free Full Text]
7. de Lezo JS, Medina A, Pan M, et al. Rapamycin-eluting stents for the treatment of unprotected left main coronary disease Am Heart J 2004;148:481-485.[Medline]
8. Chieffo A, Stankovic G, Bonizzoni E, et al. Early and mid-term results of drug-eluting stent implantation in unprotected left main Circulation 2005;111:791-795.[Abstract/Free Full Text]
9. Park SJ, Kim YH, Lee BK, et al. Sirolimus-eluting stent implantation for unprotected left main coronary artery stenosis: Comparison with bare metal stent implantation J Am Coll Cardiol 2005;45:351-356.[Abstract/Free Full Text]
10. Valgimigli M, Malagutti P, Aoki J, et al. Sirolimus-eluting versus paclitaxel-eluting stent implantation for the percutaneous treatment of left main coronary artery disease: a combined RESEARCH and T-SEARCH long-term analysis J Am Coll Cardiol 2006;47:507-514.[Abstract/Free Full Text]
11. Price MJ, Cristea E, Sawhney N, et al. Serial angiographic follow-up of sirolimus-eluting stents for unprotected left main coronary artery revascularization J Am Coll Cardiol 2006;47:871-877.[Abstract/Free Full Text]
12. Chieffo A, Park SJ, Valgimigli M, et al. Favorable long-term outcome after drug-eluting stent implantation in nonbifurcation lesions that involve unprotected left main coronary artery: a multicenter registry Circulation 2007;116:158-162.[Abstract/Free Full Text]
13. Chieffo A, Morici N, Maisano F, et al. Percutaneous treatment with drug-eluting stent implantation versus bypass surgery for unprotected left main stenosis: a single-center experience Circulation 2006;113:2542-2547.[Abstract/Free Full Text]
14. Lee MS, Kapoor N, Jamal F, et al. Comparison of coronary artery bypass surgery with percutaneous coronary intervention with drug-eluting stents for unprotected left main coronary artery disease J Am Coll Cardiol 2006;47:864-870.[Abstract/Free Full Text]
15. Palmerini T, Marzocchi A, Marrozzini C, et al. Comparison between coronary angioplasty and coronary artery bypass surgery for the treatment of unprotected left main coronary artery stenosis (the Bologna Registry) J Am Coll Cardiol 2006;98:54-59.
16. Buszman PE, Kiesz SR, Bochenek A, et al. Acute and late outcomes of unprotected left main stenting in comparison with surgical revascularization J Am Coll Cardiol 2008;51:538-545.[Abstract/Free Full Text]
17. Baim DS, Mauri L, Cutlip DC. Drug-eluting stenting for unprotected left main coronary artery disease: are we ready to replace bypass surgery? J Am Coll Cardiol 2006;47:878-881.[Free Full Text]
18. Kereiakes DJ, Faxon DP. Left main coronary revascularization at the crossroads Circulation 2006;113:2480-2484.[Free Full Text]
19. Hannan EL, Wu C, Bennett EV, et al. Risk stratification of in-hospital mortality for coronary artery bypass graft surgery J Am Coll Cardiol 2006;47:661-668.[Abstract/Free Full Text]
20. Wu C, Hannan EL, Walford G, et al. A risk score to predict in-hospital mortality for percutaneous coronary interventions J Am Coll Cardiol 2006;47:654-660.[Abstract/Free Full Text]
21. Rosenbaum PR, Rubin DB. Reducing bias in observational studies using subclassification on the propensity score J Am Stat Assoc 1984;79:516-524.
22. Rosenbaum PR, Rubin DB. The central role of the propensity score in observational studies for causal effects Biometrika 1983;70:41-55.[Abstract/Free Full Text]
23. Allison PD. Survival analysis using the SAS system: a practical guideCary, NC: SAS Institute; 1995.
24. Hannan EL, Racz MJ, McCallister BD, et al. A comparison of three-year survival after coronary artery bypass graft surgery and percutaneous transluminal coronary angioplasty J Am Coll Cardiol 1999;33:63-72.[Abstract/Free Full Text]
25. Taggart DP, Thomas B. Ferguson Lecture Coronary artery bypass grafting is still the best treatment for multivessel and left main disease, but patients need to know 2006;82:1966-1975.
26. Ong AT, Serruys PW, Mohr FW, et al. The SYNergy between percutaneous coronary intervention with TAXus and cardiac surgery (SYNTAX) study: design, rationale, and run-in phase Am Heart J 2006;151:1194-1204.[Medline]

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