Limited data exist regarding drug-eluting stent (DES) versus bare metal stent (BMS) use in older patients. From the National Heart, Lung, and Blood Institute Dynamic Registry, 5,089 percutaneous coronary intervention (PCI)-treated patients were studied (October 2001 to August 2006). The differences in 1-year safety (death, myocardial infarction, and their composite) and efficacy (target vessel revascularization [TVR] with PCI and repeat revascularization) outcomes were compared between the patients who received DESs versus BMSs within each age group: <65 years (n = 2,680); 65 to 79 years (n = 1,942); ≥80 years (n = 443). No differences were found in the safety outcomes by stent type in any age group at 1 year. Regarding the effectiveness, lower rates of TVR with PCI and repeat revascularization were observed in the DES patients across all age groups. After propensity-adjusted analysis, the risk of TVR with PCI and repeat revascularization favored DES versus BMS with patients <65 years old (7.4% vs 14.6%, hazard ratio [HR] 0.44, 95% confidence interval [CI] 0.32 to 0.60; 12.3% vs and 17.4%, HR 0.65, 95% CI 0.51 to 0.84, respectively), 65 to 79 years old (4.8% vs 9.5%, HR 0.50, 95% CI 0.31 to 0.80; and 7.6% vs 12.3%, HR 0.62, 95% CI 0.44 to 0.88, respectively), and ≥80 years old (4.5% vs 10.4%, HR 0.15, 95% CI 0.05 to 0.44; and 6.0% vs 14.5%, HR 0.18, 95% CI 0.08 to 0.40, respectively). In conclusion, significant reductions in TVR with PCI and repeat revascularization were noted in all 3 age groups without increases in death or myocardial infarction in this large multicenter PCI registry. Our data support the use of DES, regardless of age.
To date, limited studies exist regarding percutaneous coronary intervention (PCI) in the older patient population. Most randomized studies have excluded these patients because of co-morbid conditions and the heightened cardiovascular risk. Among the observational studies confined to drug-eluting stents (DESs) and stratified by age, variable benefit was noted in older patients. Of the 2 studies comparing DES and bare metal stents (BMSs) in older patients, improved survival was seen with DESs. Although provocative, these results are discordant with our knowledge of DES outcomes and deserve confirmation. Accordingly, using the National Heart, Lung, and Blood Institute-sponsored Dynamic Registry, we evaluated the effect of age on the safety and efficacy of DESs versus BMSs in consecutive patients undergoing PCI.
Methods
The methods and characteristics of the Dynamic Registry have been previously described. In brief, this was a multicenter North American registry of consecutive patients undergoing PCI. There were 5 recruitment waves, with approximately 2,000 patients enrolled in each wave across 27 clinical centers. The present analysis was restricted to the most contemporary 3 waves, and all patients had received ≥1 stent. The BMS patients were drawn from wave 3 (2001; total n = 2,047, BMS patients, n = 1,763) and the DES patients were recruited from waves 4 (2004; total n = 2,112, DES patients, n = 1,459) and 5 (2006; total n = 2,177, DES patients, n = 1,867). A notable large selection bias was found in stent type (DES and BMS) in waves 4 and 5, with the “sicker” patients (i.e., cardiogenic shock) tending to be given BMSs. To minimize the confounding of the results, the patients in waves 4 and 5 who received BMSs were excluded (n = 712).
The baseline, procedural, and in-hospital outcome data were collected from the 5,089 PCI-treated patients included in the present study. The patients were arbitrarily divided into 3 age strata: <65 years, 65 to 79 years, and ≥80 years. Thereafter, each age category was subdivided by stent type (BMS or DES). Within each age category, the BMS and DES groups were compared for patient demographics, angiographic and lesion characteristics, patient-specific procedural data and outcomes, and treatment strategy/device use. All patients were interviewed at 30 days, 6 months, and 1 year after PCI to assess vital status, clinical symptoms, coronary events, and cardiac hospitalizations. All patients provided informed consent. The institutional review boards at the clinical sites and the University of Pittsburgh data coordinating center (Pittsburgh, Pennsylvania) approved the research protocol.
The safety outcomes included death and myocardial infarction (MI). Death was defined as all-cause mortality. MI was defined as ≥1 of 2 criteria: evolutionary ST-segment elevation, new Q waves on 2 contiguous electrocardiogram leads, or new left bundle branch block; or elevated cardiac biomarkers reflecting myocardial necrosis, such as creatine kinase-MB ≥3 times the upper limit of normal, total creatine kinase ≥3 times the upper limit of normal (only if creatine kinase-MB was not available), or an elevated troponin level greater than the upper limit of normal.
The efficacy outcomes included target vessel revascularization (TVR) and repeat revascularization. Patient and lesion level data were collected for patients undergoing any repeat PCI during follow-up, although the vessel information was not collected for patients undergoing coronary artery bypass grafting. TVR was defined as revascularization along the length of the index-treated vessel within the follow-up period using PCI. Repeat revascularization was defined as undergoing either coronary artery bypass grafting or PCI within the follow-up period.
A stratified analysis was performed to examine the association between stent type and age group. Within each age strata, the patient characteristics, including demographics, medical history, cardiac presentation, periprocedural medications, procedural characteristics, and in-hospital outcomes, were compared between the stent types using the Student t test or Wilcoxon nonparametric test for continuous variables and the chi-square test or Fisher’s exact test for categorical variables. Similar methods were used for the lesion-level analyses. The 1-year event rates were calculated using the Kaplan-Meier method, and unadjusted comparisons of survival curves were performed using the log-rank test. Patients who did not experience the outcome of interest were censored at the last known date of follow-up or at 1 year if follow-up extended beyond 1 year.
Cox proportional hazards modeling was used to estimate the 1-year hazard ratios (HRs) for adverse clinical events in relation to stent type for each age strata. A propensity score approach was used to balance the factors associated with the nonrandom assignment of treatment time (earlier recruitment wave versus later recruitment wave) using SAS (SAS Institute, Cary, North Carolina) Logistic regression analysis was used initially to identify the variables to include in each propensity score (1 for <65 years, 1 for 65 to 79 years, and 1 for ≥80 years). The models were conservative, such that it included variables with p <0.40. A probability score was created for each study participant using the parameter estimates for the variables in the model. The score as a continuous variable was then included in the outcome models. The score was also evaluated as quartiles, but the results were similar. The following demographic, angiographic, and procedural characteristics were considered: age, race, gender, body mass index, previous PCI, previous coronary artery bypass grafting, previous MI, diabetes mellitus, co-morbid conditions (hypertension, dyslipidemia, congestive heart failure, chronic kidney disease, peripheral vascular disease, obstructive pulmonary disease, and cancer), lumen irregularities, vessel disease, reason and urgency for revascularization, cardiogenic shock, procedural medications (thrombolytics, glycoprotein IIb/IIIa inhibitors, and thienopyridines), and evidence of thrombus, ulcerations, presence of calcium, tortuosity, lesion classification (type C), lesion location, number of significant lesions, and individual off-label characteristics (e.g., restenotic lesion, lesion in a bypass graft, lesion length >30 mm, or reference-vessel diameter <2.5 mm or >3.75 mm). The corresponding c-statistic for the models by age strata was 0.75, 0.75, and 0.81. Covariate balance between the DES and BMS patients in each age strata was assessed after adjustment for the propensity score as a continuous covariate using logistic regression analysis. Given the temporal change in the prescribing patterns from the BMS to the DES era, all outcomes were adjusted for prespecified medications considered standard medical therapy (i.e., cholesterol modifying agents, β blockers, angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, aspirin, and thienopyridines). Proportional hazards assumptions were evaluated and met. Two-sided p <0.05 was considered statistically significant.
Results
The age range for the 5,089 included patients was 25 to 95 years. The patients <65 years old receiving DES compared to BMS were more likely to be nonwhite, present with a greater prevalence of cardiovascular risk factors and were more likely to have undergone previous PCI but less likely to have congestive heart failure during hospitalization ( Table 1 ). Significant differences were present in the primary indication for revascularization, with fewer patients presenting with acute MI and more presenting with asymptomatic coronary artery disease or other reasons in the DES group. The patients 65 to 79 years old with DES were less commonly women but had greater prevalence of diabetes and dyslipidemia and more commonly had undergone a previous revascularization procedure with PCI. The frequency of previous/in-hospital congestive heart failure was lower in those treated with DES, but renal disease was more prevalent. A shift in the primary revascularization indication by stent type was seen, with greater rates of DES use in those with stable angina pectoris and asymptomatic coronary artery disease. Few significant differences by stent type were found among the patients ≥80 years old, although those treated with DESs were more likely to be dyslipidemic and to have hypertension (p = 0.06). Similar to the other age groups, the primary indication for revascularization showed a greater percentage of patients treated for stable angina and asymptomatic coronary artery disease among the DES patients, with fewer patients undergoing revascularization for unstable angina (p = 0.08).
| Characteristic | Age Groups (years) | |||||
|---|---|---|---|---|---|---|
| <65 (n = 2,697) | 65–79 (n = 1,947) | ≥80 (n = 445) | ||||
| BMS (n = 897) | DES (n = 1,800) | BMS (n = 704) | DES (n = 1,243) | BMS (n = 162) | DES (n = 283) | |
| Women | 28.0% | 26.7% | 43.9% | 37.7% ⁎ | 43.8% | 47.3% |
| Ethnic group | ||||||
| White | 76.7% | 71.5% † | 81.7% | 78.6% | 88.9% | 85.9% |
| Black | 15.2% | 18.1% | 10.4% | 13.4% | 6.8% | 10.6% |
| Asian | 3.6% | 3.6% | 3.1% | 2.4% | 3.1% | 1.4% |
| Hispanic | 4.3% | 6.4% | 4.8% | 5.4% | 1.2% | 1.8% |
| Other | 0.2% | 0.4% | 0.0% | 0.2% | 0.0% | 0.4% |
| Current smoker | 37.1% | 35.6% | 12.7% | 10.7% | 4.2% | 4.3% |
| Diabetes mellitus | 27.3% | 34.4% ‡ | 32.9% | 37.8% † | 22.8% | 23.7% |
| Hypertension | 68.4% | 73.7% ⁎ | 80.1% | 83.6% | 79.5% | 86.2% |
| Hypercholesterolemia | 70.5% | 76.1% ⁎ | 71.3% | 82.4% ‡ | 58.8% | 76.4% ‡ |
| Previous coronary stent | 18.7% | 29.8% ‡ | 19.7% | 28.1% ‡ | 19.1% | 21.6% |
| Previous coronary bypass | 12.7% | 12.4% | 23.0% | 26.0% | 18.5% | 24.7% |
| Previous myocardial infarction | 24.5% | 23.5% | 28.4% | 25.7% | 26.1% | 24.6% |
| Heart failure (history) | 8.2% | 6.4% | 17.1% | 13.0% † | 18.7% | 17.2% |
| Heart failure during hospitalization | 5.7% | 4.0% † | 11.2% | 8.3% † | 10.6% | 12.4% |
| Mean ejection fraction | 52.4% | 53.1% | 50.4% | 51.9% | 51.3% | 51.6% |
| Number of narrowed coronary arteries | ||||||
| 1 | 42.9% | 41.2% | 32.5% | 28.6% | 30.2% | 24.4% |
| 2 | 32.3% | 33.0% | 31.8% | 33.1% | 30.9% | 31.1% |
| 3 | 24.6% | 25.6% | 35.4% | 38.1% | 37.7% | 44.5% |
| Primary indication | ||||||
| Myocardial infarction | 34.8% | 29.3% ‡ | 23.7% | 22.5% ‡ | 28.4% | 26.1% |
| Unstable angina pectoris | 34.6% | 34.8% | 45.5% | 33.7% | 45.1% | 34.6% |
| Stable angina pectoris | 22.2% | 19.3% | 17.9% | 25.0% | 13.6% | 19.8% |
| Asymptomatic coronary disease | 7.3% | 12.2% | 9.7% | 13.6% | 10.5% | 13.8% |
| Other | 1.1% | 4.4% | 3.3% | 5.1% | 2.5% | 5.7% |
| Noncardiac, co-morbid disease | ||||||
| Cerbrovascular | 4.4% | 4.7% | 8.5% | 10.7% | 11.1% | 12.8% |
| Renal | 5.0% | 6.6% | 8.4% | 11.5% † | 13.0% | 13.9% |
| Peripheral disease | 6.0% | 5.6% | 12.5% | 11.4% | 13.0% | 13.5% |
| Pulmonary | 6.7% | 6.9% | 11.0% | 9.6% | 9.3% | 8.5% |
| Cancer | 3.7% | 3.5% | 11.0% | 11.3% | 13.6% | 14.2% |
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