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(Circulation. 2004;110:1598-1604.)
© 2004 American Heart Association, Inc.
Coronary Heart Disease |
From Ospedali Riuniti di Bergamo, Bergamo, Italy (G.G., G.M.); Columbia University Medical Center and the Cardiovascular Research Foundation, New York, NY (G.W.S., A.L., R.M.); Mid Carolina Cardiology, Charlotte, NC (D.A.C.); Moses Cone Memorial Hospital, Greensboro, NC (T.S.); Duke Clinical Research Institute, Durham, NC (J.E.T.); Washington Adventist Hospital, Tacoma Park, Md (M.T.); Virginia Beach General Hospital, Virginia Beach, Va (J.J.G.); William Beaumont Hospital, Royal Oak, Mich (C.L.G.); and Hospital Gregorio Maranon, Madrid, Spain (E.G.).
Correspondence to Gregg W. Stone, MD, Cardiovascular Research Foundation, 55 E 59th St, 6th Floor, New York, NY 10022. E-mail gstone{at}crf.org
Received April 14, 2004; revision received June 24, 2004; accepted July 21, 2004.
| Abstract |
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Methods and Results In the CADILLAC trial, 2082 patients with AMI were randomized to balloon angioplasty, angioplasty plus abciximab, stenting alone, or stenting plus abciximab. No patient was excluded on the basis of advanced age; patients ranging from 21 to 95 years of age were enrolled. One-year mortality increased for each decile of age, exponentially after 65 years of age (1.6% for patients <55 years, 2.1% for 55 to 65 years, 7.1% for 65 to 75 years, 11.1% for patients >75 years; P<0.0001). Elderly patients also had increased rates of stroke and major bleeding compared with their younger counterparts. Among elderly patients (
65 years), 1-year rates of ischemic target revascularization (7.0% versus 17.6%; P<0.0001) and subacute or late thrombosis (0% versus 2.2%; P=0.005) were reduced with stenting compared with balloon angioplasty. Routine abciximab administration, although safe, was not of definite benefit in elderly patients. Rates of mortality, reinfarction, disabling stroke, and major bleeding in the elderly were independent of reperfusion modality.
Conclusions Despite contemporary mechanical reperfusion strategies, mortality, major bleeding, and stroke rates remain high in elderly patients undergoing primary percutaneous coronary intervention, outcomes that are not affected by stents or glycoprotein IIb/IIIa inhibitors. By reducing restenosis, however, stent implantation improves clinical outcomes in elderly patients with AMI.
Key Words: myocardial infarction platelet aggregation inhibitors stents
| Introduction |
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Primary coronary balloon angioplasty has been shown to be beneficial in high-risk patient groups, including the elderly.10,11 Angioplasty techniques have evolved over the years, however, and the impact of age on outcomes of patients with AMI undergoing contemporary mechanical reperfusion strategies is unknown. Moreover, whether the routine implantation of stents and/or the use of potent antiplatelet antagonists are safe and effective in the elderly is unknown. We therefore examined the database from the Controlled Abciximab and Device Investigation to Lower Late Angioplasty Complications (CADILLAC) trial to determine the optimal reperfusion modality in elderly patients presenting with AMI.
| Methods |
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All patients received preprocedural aspirin. Intravenous ß-blockade and an oral thienopyridine loading dose were recommended before angiography. Crossover to stent implantation was permitted in patients randomized to PTCA for residual stenosis of >50% despite prolonged balloon inflations or severe dissection. Patients randomized to abciximab (ReoPro, Centocor) received a bolus of 0.25 mg/kg body weight, followed by a 12-hour intravenous infusion at a rate of 0.125 µg · kg1 · min1. Bailout abciximab use was permitted in those randomized to not receive abciximab for refractory no reflow or persistent residual thrombus. After the intervention, patients received 325 mg aspirin daily and ß-blockers and ACE inhibitors if not contraindicated. Thienopyridine use was continued for 4 weeks in stented patients. Clinical follow-up was performed at 1, 6, and 12 months. Follow-up angiography, prespecified at 7 months in a subgroup of 900 consecutive eligible patients, was completed in 656 patients (73%).
Data Collection, Definitions, and Outcome Variables
Independent study monitors verified 100% of case report form data onsite, and all primary end-point events were adjudicated by an independent committee blinded to randomization allocation. Core laboratory angiographic analysis was performed as previously described.13 The primary end point was a composite of major adverse cardiac events, defined as death from any cause, reinfarction, repeated ischemic target vessel revascularization, or disabling stroke. The component definitions of the primary end point have previously been reported.12
Statistical Analysis
Baseline demographic, angiographic and procedural variables, and clinical outcomes as a function of age were determined by examining 4 prespecified age groups (<55, 55 to 65, 65 to 75, and >75 years of age). The impact of assigned treatment modality on major adverse cardiac events was then examined in pooled analysis (stent versus PTCA, abciximab versus no abciximab) stratified by age (young, <65 years; elderly,
65 years). Fishers exact test was used for pairwise comparison of categorical variables, and the
2 test was used for trend across the 4 age strata. Continuous variables are presented as median with interquartile ranges (IQRs) and were compared by the Kruskal-Wallis test. Time-to-event data are summarized and displayed as Kaplan-Meier estimates and were compared with the log-rank test. Multivariate Cox proportional-hazards regression analyses were performed to determine the independent clinical and angiographic correlates of 1-year outcomes, selecting baseline variables with entry/stay criteria of P<0.10. Variables entered into the model included age (as a continuous variable), gender, diabetes, hypertension, current cigarette smoking, creatinine clearance, prior AMI or bypass surgery, Killip class, infarct artery, triple-vessel disease, time to reperfusion (as a continuous variable), baseline and final TIMI flow grades, left ventricular ejection fraction, stent implantation, and abciximab use. All probability values are 2 sided, and all analyses are by intention to treat. Statistical significance was determined at the P<0.05 level.
| Results |
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As shown in Table 2, elderly compared with younger patients had more extensive coronary artery disease and smaller infarct-related arteries. Baseline and postprocedure TIMI flows were independent of age, as were use of stents and abciximab and final diameter stenosis achieved.
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30-Day and 1-Year Outcomes Stratified by Age
As seen in Table 3, the rates of mortality, stroke, and major bleeding were significantly increased in elderly patients at 30 days compared with their younger counterparts. At 1 year, mortality rates were strikingly higher in the elderly, with exponential increases after 65 years of age, both as a consequence of cardiac and noncardiac mortality. The incidence of stroke and major bleeding was also increased in the elderly at 1 year. By multivariate analysis, advanced age was a powerful independent determinate of 1-year mortality (hazard ratio, 1.06; 95% CI, 1.04 to 1.09; P<0.0001), disabling stroke (hazard ratio, 1.07; 95% CI, 1.01 to 1.13; P=0.02), and major bleeding (hazard ratio, 1.05; 95% CI, 1.03 to 1.09; P<0.0001). In contrast, the rates of subacute thrombosis, reinfarction, and ischemic target vessel revascularization were independent of age at both 30 days and 1 year. Similarly, the incidence of angiographic restenosis and infarct artery reocclusion was independent of age (Figure).
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Impact of Treatment Arm on Major Adverse Cardiac Events in Elderly Compared With Young Patients
The impact of mechanical reperfusion modality on 30-day outcomes as a function of age appears in Table 4. Elderly patients assigned to stent implantation rather than PTCA had lower 30-day rates of subacute thrombosis and ischemic target vessel revascularization; the 30-day rates of other major adverse events in elderly patients were similar with randomization to stent or PTCA. There were no statistically significant differences in 30-day adverse event rates in elderly patients randomized to abciximab compared with no abciximab. In contrast, younger patients assigned to abciximab compared with no abciximab experienced reduced 30-day rates of subacute thrombosis and ischemic target vessel revascularization; no significant reduction in 30-day adverse event rates with randomization to stenting rather than PTCA was present in the younger cohort. However, by the Breslow-Day test for homogeneity, no formal interaction existed between abciximab versus no abciximab randomization and age with regard to either the 30-day rate of ischemic target vessel revascularization (P=0.25) or composite major adverse cardiac events (P=0.65).
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One-year major adverse cardiac outcomes stratified by age and treatment arm are shown in Table 5. The 1-year rates of ischemic target vessel revascularization were markedly reduced in both elderly and young patients randomized to stenting rather than PTCA, consistent with a marked reduction in angiographic restenosis. Elderly patients randomized to stent implantation also had fewer episodes of subacute or late thrombosis at 1 year. Although abciximab administration in the elderly was safe, the 1-year rates of major adverse events were similar in elderly patients randomized to abciximab compared with no abciximab. In contrast, younger patients randomized to abciximab had a persistent reduction in subacute or late thrombosis rates at 1 year but overall similar rates of ischemic target vessel revascularization and composite major adverse cardiac events. By interaction testing, the effects of abciximab randomization on 1-year ischemic target vessel revascularization and composite major adverse cardiac events were similar in the young and elderly patient (P=0.32 and P=0.62, respectively).
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| Discussion |
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The present large study points out the challenge of managing elderly patients presenting with AMI. Not only is biological age increased, but elderly patients are more likely to be female; more often have hypertension, hyperlipidemia, and prior cerebrovascular and peripheral vascular disease; and present later in the course of infarction than younger patients. In the present series, despite the coexistence of multiple risk factors potentially complicating interventional therapy (reduced systolic function, more extensive coronary artery disease, smaller vessels, etc), the final percent diameter stenosis and rate of TIMI-3 flow achieved in the infarct vessel of elderly patients were similar to those in younger patients. Reassuringly, the time from presentation in the emergency room to angioplasty was also similar in elderly and young patients. As a result, the mortality rate at 1 year after primary PCI was "only" 8.4% in patients
65 years of age, acceptably low compared with prior published studies of patients treated conservatively or with thrombolytic therapy in whom 1-year mortality has been reported in 15% to 30% of patients 65 to 70 years of age.3,6,1417 Rates of disabling stroke, reinfarction, and ischemic target vessel revisualization were also age independent, as were angiographic restenosis and infarct artery reocclusion. These favorable results are consistent with the findings from a small (87 patient) randomized trial by de Boer et al14 in which primary angioplasty compared with streptokinase reduced the 30-day composite incidence of death, reinfarction, or stroke in patients >75 years of age from 29% to 9% (P=0.01). Moreover, event-free survival in elderly patients in the present study was greater than previously reported after primary PTCA,15,18 possibly reflecting the broader use of stents and glycoprotein IIb/IIIa inhibitors (including the ability to "cross over" to these modalities for suboptimal results, even in the control arms), as well as other technique and pharmacological advances. Thus, patients with AMI should not be excluded from primary PCI on the basis of age.
In previous studies of stent implantation and glycoprotein IIb/IIIa use in patients with AMI, randomized patients compared with those excluded were younger, were more frequently male, and had significantly larger reference vessel size.1921 The utility of stents and IIb/IIIa inhibitors in the elderly is thus unknown. A concerted effort to recruit elderly patients in CADILLAC resulted in randomization of patients up to 95 years of age; indeed, randomization of 743 patients
65 years of age and 243 patients
75 years of age affords an important opportunity to examine the safety and efficacy of these reperfusion modalities in the elderly. This analysis showed significant benefits of a routine stent implantation strategy in the elderly, with reduced 30-day and 1-year rates of subacute thrombosis and ischemic target vessel revascularization and a marked reduction in angiographic restenosis at 7 months. Abciximab use in the elderly was safe, with only a slight (age-independent) risk of thrombocytopenia noted,12 without increased risk of major bleeding. In contrast to young patients in whom abciximab reduced the 30-day incidence of ischemic target vessel revascularization and composite major adverse cardiac events, no statistically significant benefits of abciximab were present in elderly patients. Interaction testing, however, found no significant age dependence of the effect of abciximab, suggesting that had more elderly patients been enrolled, a beneficial effect of abciximab in terms of enhancing 30-day event-free survival in the elderly (as seen in the entire study cohort) may have become evident.22 Finally, no benefits of either stents or abciximab were present in terms of reducing death or reinfarction in either the elderly or young patients, emphasizing the need for newer treatment strategies to further improve event-free survival after primary PCI.
Despite the reduction in mortality of elderly patients treated with primary PCI rather than thrombolytic therapy,14,23 patients
75 years of age still have an in-hospital mortality rate that is 5-fold higher than in those <75 years of age.24 Furthermore, despite the application of contemporary reperfusion modalities in the present study, 1-year mortality exponentially increased in patients after 65 years of age and was increased 7-fold in patients
75 years of age. Both cardiac and noncardiac causes of death were more frequent in the elderly. Myocytes are continuously lost as the heart ages, and senescent cells demonstrate increased susceptibility to microvasculature reperfusion injury.25,26 The high prevalence of cardiac and extracardiac comorbidities may also contribute to the reduced survival in elderly patients undergoing primary PCI,27 although by multivariate analysis, advanced age was a powerful independent determinant of both early and late mortality.
Study Limitations
As a secondary analysis with multiple statistical comparisons, this study should be viewed as hypothesis generating rather than definitive. Because case selection was left to the discretion of the investigator, elderly patients at especially high risk may not have been enrolled. The protocol also excluded patients with cardiogenic shock, those with saphenous vein graft culprit vessels, and those requiring multivessel intervention. Results of this study therefore apply to selected elderly patients undergoing PCI in centers with experienced operators. Similarly, a screening log was not available to use to examine the characteristics of patients excluded from consent. The impact of race and ethnicity on the age-dependent survival after primary angioplasty is also unknown. Finally, although to date this is the largest primary PCI study examining outcomes of elderly patients with AMI, additional risks or benefits of stents or glycoprotein IIb/IIIa inhibitors might have become evident had more patients been enrolled. For example, <30% power was present to detect the observed reduction from 9.2% to 6.5% in the 30-day composite major adverse event rate in patients
65 years of age randomized to no abciximab compared with abciximab. Moreover, formal interaction testing supports the fact that this difference may be real, consistent with the effect of abciximab in the entire study cohort.22
| Conclusions and Clinical Implications |
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65 years of age continue to have a substantially increased risk of death, stroke, and major bleeding at 30 days and 1 year compared with their younger counterparts regardless of reperfusion strategy, warranting close observation, meticulous attention to adjunct pharmacological therapy, and appropriate prognostic stratification. | References |
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