Several randomized controlled trials and observational studies have compared outcomes of percutaneous coronary interventions (PCIs) with drug-eluting stents (DESs) and coronary artery bypass grafting (CABG), but they have not thoroughly investigated the relative difference in outcomes for patients aged ≥75 years. In this study, a total of 3,864 patients receiving DES and CABG (1,932 CABG-DES pairs) with multivessel coronary disease were propensity matched using multiple patient risk factors and were compared with respect to 3 outcomes (mortality, stroke/myocardial infarction [MI]/mortality, and repeat revascularization) at 2.5 years with a mean follow-up of 18 months. The mortality rates (DES/CABG hazard ratio 1.06, 95% confidence interval 0.87 to 1.30) and the stroke/MI/mortality rates (DES/CABG hazard ratio 1.15, 95% confidence interval 0.97 to 1.38) for the 2 procedures were not significantly different. Repeat revascularization rates were significantly higher for patients who received DESs. In conclusion, older patients experienced similar mortality and stroke/MI/mortality rates for CABG and PCI with DES, although repeat revascularization rates were higher for patients undergoing PCI with DES.
The purposes of this study are to compare patient outcomes of percutaneous coronary interventions (PCIs) with drug-eluting stents (DESs) and coronary artery bypass grafting (CABG) for patients aged ≥75 years with coronary artery disease and to examine how relative outcomes vary for 4 important risk factors for revascularization (ejection fraction [EF], chronic obstructive pulmonary disease [COPD], diabetes, and proximal left anterior descending [LAD] disease [with stenosis ≥70%]).
Methods
End points in the study included 2.5-year mortality, stroke/myocardial infarction (MI)/mortality, and repeat revascularization. The mean follow-up time was 1.5 years; all procedures performed from January 1, 2008 to December 31, 2010 were followed through December 31, 2010.
The primary databases used for the study were New York State’s clinical registries for PCI and for CABG, the Percutaneous Coronary Interventions Reporting System (PCIRS) and the Cardiac Surgery Reporting System (CSRS), respectively. These registries contain detailed information on patient demographics, risk factors, hemodynamic state, left ventricular function, coronary vessels diseased and attempted, complications, procedure choices, provider identifiers, discharge status, and in-hospital adverse outcomes. All common data elements in the 2 databases have identical definitions. PCIRS also contains information on the type(s) of device used for each attempted lesion, including the type and brand of stent used.
Completeness of data reporting is monitored by matching PCIRS to New York’s acute care hospital discharge database, the Statewide Planning and Research Cooperative System (SPARCS) and to the Department of Health’s Ambulatory Surgery Database. PCIRS and CSRS records were matched with SPARCS records using unique hospital identifiers along with patient identifiers and admission, surgery, and discharge dates. Also, in-hospital outcomes are matched to SPARCS to ensure accuracy, and the Department of Health’s utilization review agent audits samples of records from hospitals to ensure the accuracy of risk factor reporting. SPARCS data were also used to identify emergency admissions with MI or stroke as the principal diagnoses in the follow-up period. Patient identifiers in the PCIRS and CSRS were used to link patients in the index revascularization procedure to future admissions in PCIRS and CSRS to identify subsequent revascularization. All staged PCIs were excluded from the repeat revascularization measure. In addition, patient identifiers were used to link the index procedure to New York State’s vital statistics data to identify deaths that occurred after discharge.
A total of 90,686 patients were confirmed to have undergone PCI with DES and no bare-metal stents, and a total of 26,323 patients were confirmed to have undergone isolated CABG surgery from January 1, 2008 to December 31, 2010. Of these patients, we sequentially excluded those who were aged <75 years (90,940 patients), patients who had previous revascularization procedure (10,349), had preprocedural cardiogenic shock (29), left main disease (2,441), an MI in the 24 hours before the index procedure (1,065), were from out-of-state (394), had single-vessel disease (4,846), or had multiple revascularization procedures in the same admission (18). All other patients undergoing revascularization from January 1, 2008 to December 31, 2010 in New York State (6,927, of which 4,299 underwent DES and 2,628 underwent CABG surgery) were used to identify one-to-one propensity-matched pairs of patients with similar risk profiles. These propensity-matched patients were then followed through the end of 2010 to compare the mortality, stroke/MI/mortality, and repeat revascularization for patients receiving DES and CABG. A total of 59 different hospitals were in the study.
Patients receiving DES and CABG in the study were compared for numerous patient characteristics, including demographics, co-morbidities, ventricular function, preprocedural MI, hemodynamic state, and vessels diseased. Chi-square tests were used to determine significant differences in the use of the 2 types of revascularization for each patient characteristic. Because patients were not randomized to DES and CABG, and because many of the prevalences of the characteristics mentioned previously differed between the 2 groups, propensity score matching was used to identify sets of DES-CABG surgery pairs matched on those characteristics so that the selection bias associated with our observational study could be minimized. The propensity score was derived by developing a logistic regression model that predicted the probability that a given patient would receive CABG surgery on the basis of the patient characteristics mentioned previously. This value was used to match patients without replacement on a one-to-one basis so as to minimize the overall distance in propensity scores between the groups. Differences between the 2 matched samples in the prevalence of propensity model variables were tested using standardized differences in the observed prevalence of the variables in the matched groups. The propensity-matched pairs were then used to analyze differences in outcomes between DES and CABG surgery. Remaining differences in prevalences of propensity model variables were further reduced using multivariable (Cox proportional hazards) models for adjustment along with robust standard errors to control for clustering of patients in matched pairs, taking into account that the samples were matched.
Adverse outcome rates of DES and CABG surgery were also compared for 4 patient characteristics (EF, COPD, diabetes, and proximal LAD disease [with stenosis ≥70%]) that were preselected on the basis of their high risk and use in other studies. This was done for each characteristic by comparing differences in each of the outcomes for matched pairs containing the same value of that characteristic (e.g., all matched pairs in which both patients were diabetics). Adjusted hazard ratios (HRs) were obtained through the same method mentioned previously. All tests were 2-sided and conducted at the 0.05 level, and all analyses were conducted in SAS 9.1 (SAS Institute, Cary, North Carolina).
Results
A total of 6,927 patients aged ≥75 years (4,299 patients who received DES and 2,628 CABG) were subjected to propensity matching and 3,864 patients (1,932 pairs and 74% of all patients receiving CABG) were propensity matched. The variables used in the propensity model are all the variables in Table 1 , and the C statistic for the models was 0.81.
| Variable | CABG (n = 2,628) | DES (n = 4,299) | p Value |
|---|---|---|---|
| Age groups (yrs) | <0.0001 | ||
| 75–79 | 56.7 | 50.8 | |
| 80–84 | 33.9 | 33.3 | |
| ≥85 | 9.4 | 15.9 | |
| Women | 38.4 | 45.6 | <0.0001 |
| Hispanic ethnicity | 6.2 | 9.0 | <0.0001 |
| Race | |||
| White | 91.0 | 82.7 | |
| Black | 5.9 | 10.4 | |
| Other | 3.0 | 6.9 | |
| BMI (kg/m 2 ) | 0.09 | ||
| <16.5 | 0.3 | 0.2 | |
| 16.5–18.4 | 1.1 | 1.4 | |
| 18.5–24.9 | 30.4 | 30.7 | |
| 25.0–30.0 | 42.2 | 40.1 | |
| 20.1–34.9 | 18.9 | 18.8 | |
| 35.0–40.0 | 5.2 | 6.1 | |
| >40.0 | 1.8 | 2.7 | |
| EF (%) | <0.0001 | ||
| <20 | 1.4 | 0.7 | |
| 2–29 | 6.0 | 3.9 | |
| 30–39 | 13.5 | 6.8 | |
| 40–49 | 19.4 | 12.6 | |
| ≥50 | 59.8 | 75.9 | |
| Previous MI (days) | <0.0001 | ||
| 1–7 | 19.2 | 19.1 | |
| 8–14 | 6.4 | 1.8 | |
| 15–20 | 1.2 | 0.4 | |
| ≥21 | 19.3 | 10.3 | |
| None | 54.0 | 68.5 | |
| Carotid/cerebrovascular disease | 26.2 | 12.8 | <0.0001 |
| Peripheral vascular disease | 15.8 | 11.8 | <0.0001 |
| Hemodynamically unstable | 0.3 | 0.1 | 0.04 |
| Heart failure | <0.0001 | ||
| None | 79.5 | 86.4 | |
| At current admission | 16.6 | 10.5 | |
| Before current admission | 4.0 | 3.1 | |
| Malignant ventricular arrhythmia | 1.4 | 0.4 | <0.0001 |
| COPD | 27.5 | 8.9 | <0.0001 |
| Diabetes mellitus | 33.7 | 31.8 | 0.11 |
| Renal function | 0.006 | ||
| Serum creatinine level/no dialysis (mg/dl) | |||
| <1.2 | 54.9 | 57.9 | |
| 1.2–1.5 | 28.2 | 28.4 | |
| 1.6–2.0 | 10.7 | 8.4 | |
| 2.1–2.5 | 2.9 | 2.4 | |
| 2.6–3.0 | 1.0 | 0.6 | |
| >3.0 | 0.6 | 0.6 | |
| Dialysis | 1.7 | 1.7 | |
| Number of narrowed coronary arteries | <0.0001 | ||
| 2, With proximal LAD | 17.1 | 21.1 | |
| 2, Without proximal LAD | 13.4 | 49.0 | |
| 3, With proximal LAD | 38.2 | 11.1 | |
| 3, Without proximal LAD | 31.4 | 18.7 |
Table 1 presents differences in patient characteristics for patients receiving DES and CABG in New York from 2008 to 2010. As indicated, older patients, women, Hispanics, nonwhites, patients with higher EF and no previous MI, patients who were less likely to have had several different co-morbidities (carotid or cerebrovascular disease, peripheral vascular disease, hemodynamic instability, heart failure, malignant ventricular arrhythmia, COPD, and renal dialysis), and patients with fewer diseased coronary vessels and absence of proximal LAD disease had higher prevalences of PCI with DES than CABG. Table 2 demonstrates that the DES-CABG pairs that were propensity matched are quite similar, with all of the standardized differences below 10%.
| Variable | CABG (n = 1,932) | DES (n = 1,932) | Standardized Difference |
|---|---|---|---|
| Age groups (yrs) | |||
| 75–79 | 55.3 | 52.8 | 5.0 |
| 80–84 | 33.6 | 35.1 | 3.1 |
| ≥85 | 11.1 | 12.1 | 3.2 |
| Women | 41.3 | 40.5 | 1.5 |
| Hispanic ethnicity | 7.0 | 7.2 | 0.6 |
| Race | |||
| White | 88.8 | 88.5 | 1.1 |
| Black | 7.4 | 7.3 | 0.4 |
| Other | 3.8 | 4.2 | 2.4 |
| BMI (kg/m 2 ) | |||
| <16.5 | 0.4 | 0.2 | 2.9 |
| 16.5–18.4 | 1.2 | 1.1 | 0.5 |
| 18.5–24.9 | 29.8 | 30.9 | 2.4 |
| 25.0–30.0 | 40.7 | 41.3 | 1.1 |
| 20.1–34.9 | 19.8 | 18.8 | 2.6 |
| 35.0–40.0 | 6.0 | 5.4 | 2.5 |
| >40.0 | 2.2 | 2.4 | 1.4 |
| EF (%) | |||
| <20 | 0.9 | 1.2 | 2.5 |
| 2–29 | 5.3 | 5.1 | 1.2 |
| 30–39 | 12.0 | 10.7 | 3.9 |
| 40–49 | 18.3 | 17.5 | 2.0 |
| ≥50 | 63.5 | 65.5 | 4.2 |
| Previous MI (days) | |||
| 1–7 | 20.8 | 20.6 | 0.4 |
| 8–14 | 4.1 | 2.8 | 7.4 |
| 15–20 | 0.8 | 0.7 | 1.2 |
| ≥21 | 16.9 | 14.9 | 5.5 |
| None | 57.4 | 61.0 | 7.4 |
| Carotid/cerebrovascular disease | 20.7 | 18.2 | 6.4 |
| Peripheral vascular disease | 14.7 | 13.8 | 2.7 |
| Hemodynamically unstable | 0.2 | 0.2 | 0.0 |
| Heart failure | |||
| None | 82.0 | 83.6 | 4.4 |
| At current admission | 14.8 | 13.5 | 3.7 |
| Before current admission | 3.3 | 2.9 | 2.1 |
| Malignant ventricular arrhythmia | 0.8 | 0.6 | 3.1 |
| COPD | 18.2 | 15.3 | 7.8 |
| Diabetes mellitus | 33.9 | 32.6 | 2.6 |
| Renal function | |||
| Serum creatinine level/no dialysis (mg/dl) | |||
| <1.2 | 55.9 | 56.6 | 1.4 |
| 1.2–1.5 | 28.8 | 28.3 | 1.2 |
| 1.6–2.0 | 9.7 | 9.5 | 0.9 |
| 2.1–2.5 | 2.3 | 2.7 | 2.6 |
| 2.6–3.0 | 0.8 | 0.7 | 1.2 |
| >3.0 | 0.7 | 0.5 | 2.8 |
| Dialysis | 1.7 | 1.7 | 0.0 |
| Number of narrowed coronary arteries | |||
| 2, With proximal LAD | 21.4 | 23.7 | 5.5 |
| 2, Without proximal LAD | 18.1 | 18.7 | 1.6 |
| 3, With proximal LAD | 26.7 | 23.9 | 6.7 |
| 3, Without proximal LAD | 33.8 | 33.8 | 0.1 |
Table 3 indicates that there were no significant differences in mortality or stroke/MI/mortality between CABG and DES for propensity-matched patients aged ≥75 years. However, patients aged ≥75 years receiving DES had significantly higher risk-adjusted rates of repeat revascularization than propensity-matched patients undergoing CABG. Figure 1 demonstrates that crossovers occur at about 1 year for mortality and at about 8 months for stroke/MI/mortality.
| Long-Term Outcomes | Observed Rate | Kaplan-Meier Survival Estimates | Adjusted HR (95% CI) DES/CABG | p Value | ||
|---|---|---|---|---|---|---|
| CABG | DES | CABG | DES | |||
| Mortality | 11.3 | 10.7 | 15.8 | 16.9 | 1.06 (0.87–1.30) | 0.58 |
| Stroke/MI/Mortality | 14.3 | 14.7 | 19.8 | 21.9 | 1.15 (0.97–1.38) | 0.12 |
| Repeat revascularization | 3.0 | 15.7 | 4.5 | 24.1 | 7.48 (5.61–9.98) | <0.0001 |
Subgroup analyses for 4 groups of high-risk patients (low EF, COPD, diabetes, and proximal LAD disease [≥70% stenosis]) are presented for each of the outcome measures in Table 4 . For mortality, there were no significant differences for any of the subsets. CABG was associated with lower stroke/MI/mortality rates for patients without COPD and for patients with ≥1 of the 4 risk factors. For repeat revascularization, CABG surgery was associated with significantly lower rates for all subsets of patients.
