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J Am Coll Cardiol, 1998; 32:577-583 © 1998 by the American College of Cardiology Foundation |
a Centro Cuore Columbus, Milan, Italy
Manuscript received February 12, 1998; revised manuscript received May 6, 1998, accepted May 20, 1998.
Address for correspondence: Dr. Antonio Colombo, Centro Cuore Columbus via M. Buonarroti 48, 20145 Milan, Italy
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Abstract |
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Background. Elderly patients undergoing coronary revascularization are considered a high-risk group. Few data exist that relate the results of stenting in treating coronary artery disease in the elderly population.
Methods. All elderly patients 
75 years of age who underwent coronary artery stenting between March 1993 and July 1997 (n = 137) at our center were compared to the patients <75 who underwent coronary artery stenting during the same time period (n = 2,551). Long-term clinical follow-up and survival were determined for the elderly group.
Results. Elderly patients presented with lower ejection fractions (54% vs. 58%, p = 0.0001), more unstable angina (47% vs. 28%, p = 0.0001), and more multivessel disease (78% vs. 62%, p = 0.0001) than younger patients. These older patients had higher rates of procedure related complications including procedural myocardial infarction (MI) (2.9% vs. 1.7%, p = 0.2), emergency CABG (3.7% vs. 1.4%, p = 0.04), and death (2.2% vs. 0.12%, p = 0.0001). Angiographic follow-up, obtained in both groups, demonstrated significantly higher restenosis rates in the elderly versus younger patients (47% vs. 28%, p = 0.0007). Longer term clinical follow-up, which was obtained only in the elderly group, showed that at a mean follow-up period of 12 months post coronary stenting, elderly survival free from death, MI, revascularization and angina was 54% and that their overall survival was 91%. Subanalysis of the elderly patients who died showed much higher incidence of combined unstable angina (80%), prior MI (60%), lower ejection fraction (46%), multivessel disease (100%) and complex lesions (100%) than the overall group.
Conclusions. Elderly patients who undergo coronary artery stenting have significantly higher rates of procedural complications and worse six month outcomes than younger patients, especially those who present with combined unstable angina, history of MI, EF < 50%, multivessel disease and complex lesions. Overall survival in the elderly population at 12 months postcoronary artery stenting was 91% and event-free survival was 54%.
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Compared to the general population, elderly patients undergoing coronary revascularization have traditionally been more likely to present with more: complex lesions, unstable angina, comorbid conditions and lower ejection fractions (1–10). At least in part due to these facts elderly patients have traditionally had higher rates of procedure related death and complications when undergoing percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass grafting (CABG) (4–23). Despite these problems, the rates of PTCA and CABG among the elderly, between 1987 and 1990, increased by 55% and 18%, respectively.
With the advent of procedural modification, allowing the elimination of anticoagulation, coronary artery stenting has come to widespread use (24–27), including in the elderly. But do the advantages that stenting has afforded the general population translate to the elderly population with comparable procedure-related complications and long-term outcome? The present study was designed to investigate the impact of stenting in treating coronary artery disease in our elderly population 75 years of age and examines the period of time from March 1993 through July 1997.
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Methods |
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75 years of age (elderly cohort).
Stent implantation procedure.
Before stent implantation procedure, all patients received aspirin 325 mg to 500 mg. A 10,000 unit bolus of heparin was given after sheath insertion; thereafter, heparin boluses were administered during the procedure as needed to maintain an activated clotting time 250 s. The Palmaz-Schatz stent was used in 42% of the lesions, the NIR stent in 12%, the AVE stents in 7% and the Gianturco-Roubin stent in 7%. In the remaining patients other types of slotted tube or coil stents were used. Stents were either hand crimped on a balloon or premounted on a delivery system. After stent deployment, further dilatations were performed using high-pressure balloon inflations (14 atm). Since April 1993 stents have been placed with the utilization of intravascular ultrasound in the majority of cases. With the introduction of intravascular ultrasound guided coronary stenting, patients who met optimal stenting criteria did not receive any heparin or oral anticoagulant agents after the procedure. Only 3.2% of patients <75 and 1.7% of patients 75 received any type of anticoagulation therapy during this time period (no patients received dextran or dipyridamole). Ticlopidine (250 mg twice daily) was given for a period of one month and aspirin (325 mg daily) continued indefinitely.
Indications for stenting and their definitions were performed as previously reported (27). The use of >1 stent per lesion or per patient was considered multiple stenting. Each stent was counted as one stent except the short Palmaz-Schatz stents and the 4 or 8 mm Micro stents, which were counted as half stents.
Angiographic analysis. Coronary angiograms were obtained in a routine fashion. Patients received intracoronary isosorbide dinitrate before initial and postprocedural angiograms to achieve maximal vasodilatation. Vessel and lesion measurements were obtained using a computerized quantitative analysis system (QCA-CMS Version 3.0, MEDIS) according to previously described and validated edge detection algorithms using the catheter as the object of calibration (28). The following measurements were obtained both preintervention and poststent placement: reference vessel diameters, minimal lumen diameter, percent diameter stenosis and lesion length. Each stenotic segment was evaluated for the presence or absence of calcium and thrombus. Lesions were characterized according to the modified American Heart Association/American College of Cardiology classification (29).
Follow-up.
Clinical follow-up was obtained when patients were seen at the outpatient clinic or by direct telephone interview. Adjunctive information was obtained from the referring physician. Event-free survival upon clinical follow-up was defined as free from death, myocardial infarction (MI), revascularization or angina. Survival curves were generated taking into account all elderly patients who underwent stent implantation and all related deaths from the time of stent implantation. Angina symptoms were characterized according to the Canadian Cardiovascular Society classification. For patients who had clinical events, clinical follow-up ended at the time of the event. Angiographic follow-up was routinely scheduled at 5 to 6 months postprocedure for all patients with a successful procedure who had had their procedure 5 months prior to this analysis and had not undergone CABG during this period. Restenosis was defined as 50% diameter stenosis by angiography on follow-up. Diffuse restenosis was defined as a restenotic lesion >10 mm in length (30,31).
Definitions.
Procedure success was defined as 
20% residual stenosis in the target lesion poststent implantation without the occurrence of myocardial infarction, urgent coronary artery bypass graft surgery or death. Complete revascularization was achieved when there was no residual stenosis 70% in any major coronary artery or their large branches unless a bypass graft fed the territory distal to a diseased segment. Clinical events were defined as death from any cause, coronary artery bypass surgery, myocardial infarction (Q wave or nonQ wave) repeat angioplasty and vascular complications. Q wave myocardial infarction was diagnosed when there were new pathologic Q waves on electrocardiogram accompanied by an elevation in creatinine kinase levels to twice the normal level. A non-Q wave myocardial infarction was diagnosed when an elevation of the creatinine kinase to twice normal levels occurred without the development of Q waves. Vascular complications were defined as the occurrence of pseudoaneurysm, bleeding or hematoma at the access site requiring transfusion, vascular repair or external compression. Other bleeding complications were defined as gastrointestinal, neurologic or any other significant bleed other than that of the access site. Stent restenosis was defined as 50% diameter stenosis at the stented site or at the proximal or distal adjacent sites. Diffuse restenosis was defined as a 50% luminal narrowing 10 mm in length; if shorter, the restenosis was defined as focal (32,33).
Statistical analysis.
The primary clinical analysis consisted of a comparison between the two cohorts that were divided by age. Categorical variables are presented as absolute numbers (percent). Continuous variables are presented as mean values ± standard deviation. Differences between groups were evaluated by chi-square analysis for categorical data or the two-tailed Student t test for continuous data. These differences were considered statistically significant at p value 0.05. The Kaplan-Meier method was used to generate a survival curve.
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75-year-old cohort. Table 5 shows the results of angiographic follow-up. Patients who had early events (within 5 months of procedure), such as procedural CABG or death, are excluded. Stent minimal lumen diameter (MLD) and percent stenosis were significantly worse in the elderly group (2 mm vs. 1.8 mm, p = 0.03 and 33% vs. 41%, p = 0.05). Restenosis rates were higher in the elderly (47% vs. 28%, p = 0.0007). Target lesion revascularization reflected the restenosis rates and were higher in the elderly (28% vs. 19%, p = 0.02).
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Discussion |
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65 years of age postacute MI have a 30-day mortality of 21% and a one-year mortality of 34% (32) and studies such as Thrombolysis In Myocardial Infarction (TIMI) IIIB have shown improved outcome, at least in the short term, in elderly patients undergoing aggressive revascularization when presenting with unstable angina or non-Q w MI (33). Recent studies regarding CABG in the elderly report procedural mortality rates of 6% to 10% (1–5,15,16) and 30-day mortality of 8% to 14% (1,5). Roach et al. have shown that patients over age 70 who underwent coronary bypass surgery had a cumulative incidence of stroke of 12% (15). This in turn was associated with a 5- to 10-fold increase in mortality. There has also been extensive work examining the results of angioplasty in the elderly. These reports exhibit procedural mortality rates of 1.4% to 10% and an emergency CABG rate ranging from 0.7% to 7%. Thompson et al. (6) have shown a changing trend towards lower complication rates in the elderly treated with PTCA between 1980 and 1992 with procedural mortality decreasing to 1.4% and emergency CABG down to 0.7%.
Since the time of these early reports, the use of high-pressure balloon inflations, intravascular ultrasound guidance and better antiplatelet agents have contributed to the removal of anticoagulation, bringing stenting to widespread use (24–26). Although there is an extensive amount of published information regarding PTCA and CABG in the elderly, there are limited data available with regards to stenting in this population.
Coronary artery stenting in the elderly.
Early studies of stenting and standard anticoagulation reported significant vascular complications at a rate of about 16% (34). Vascular complications were even more pronounced in the elderly; Elliot et al. showed a 45% vascular complication rate for patients >70 years of age who underwent stenting (22). Removal of anticoagulation has tempered this situation. A recent analysis that compared vascular complications from two different time periods (1991–1994 vs. 1994–1995) in patients >70 years of age who underwent Palmaz-Schatz stent implantation showed an incidence of vascular complications of 13.2% and 0%, respectively (35). Our data, with the new antiplatelet regimen, show a vascular complication rate of 0.8% in the population 75 and 0.9% in the patients <75 (p = NS). In this regard we have been able to reduce what was a severe problem, and to equalize the complication rate between older and younger patients.
However, there are a number of problems that continue to exist with revascularization in the elderly population. Our results show a promising trend toward better outcome in this fragile group, but a significant difference continues to exist between results obtained in the older versus younger patients, both in short- and long-term outcome. There was a significantly higher rate of procedure-related CABG and death along with substantially more procedural myocardial infarction in the 75 cohort (Table 4). Also of concern in treating this elderly group is the fact that there is a much higher rate of angiographic restenosis (47% vs. 28%, p = 0.0007). The TLR coincides with these results and has a concurrent distribution of events (28% vs. 19%, p = 0.02). Significant differences in the elderly population that help to explain their inferior outcome include the fact that they present with lower ejection fractions, more unstable angina and a higher angina class (Table 1). It has also been documented in previous studies that older patients present with more comorbid disease (5). The angiographic lesion characteristics we found also provide an explanation for higher complication rates and worse long-term outcome. There were more ostial lesions (15% vs. 7%, p = 0.006), three-vessel disease, calcified lesions and complex lesions (72% combined B2 and C type lesions vs. 65%, p = 0.09) in the elderly compared to the younger patients. Treatment strategies did not differ greatly as average balloon size and inflation pressure were similar (Table 3). Likewise, angiographic reference diameters and lesion percent stenosis showed no significant difference (Table 2). The approach differed on the basis of adjunctive procedures and complete revascularization. More rotablation was performed in the older group (23% vs. 9%, p = 0.0001) reflecting the fact that there was a proportionately higher number of calcified lesions (30% vs. 13%, p = 0.0001). Complete revascularization was more often achieved in the younger cohort although procedure success was not significantly different (Table 3). This reflects the fact that there was more three-vessel disease in the elderly (Table 2), making complete revascularization more difficult to achieve.
These clinical and angiographic characteristics in the elderly may also help explain the fact that long-term clinical follow-up shows a high incidence of adverse events. However, despite the higher rates of procedural complications, restenosis and low rate of freedom from events, the elderly group displays a good overall survival rate on clinical follow-up post stent implantation (Figure 1).
Elderly patients with poorest outcome.
A subgroup analysis of the 10 elderly patients who died during or following stent implantation yields some interesting results. Three deaths were considered procedural; five deaths were within 1 month, with one death at 3 months and one death at 5 months. Therefore, 8 of the 10 deaths were within 1 month of stent implant and all deaths were within 5 months of procedure. It seems that if an elderly patient survived this critical period, he could expect long-term survival. The findings that set this group apart from the rest of the elderly population and portend poorer outcome include some of the classic risk factors. Five risk factors including unstable angina, prior MI, lower ejection fraction (<50%), multivessel disease and complex lesions were all much more prominent in this subgroup compared to the rest of the elderly. In fact, 8 of the 10 patients who died had 4 of these risk factors; the two remaining patients had either two or three of these characteristics. The total number of elderly patients with 4 of these risk factors is 26; therefore, the mortality for an elderly patient with these characteristics undergoing coronary artery stenting was 31%.
Limitations of the study. There are several limitations to the present study. It is a retrospective study and therefore inherently contains all the disadvantages of such a comparative analysis. In making any direct comparisons, lesion characteristics and number do differ in some respects between the elderly and younger populations and treatment strategies towards these lesions vary slightly. However, this is part of what we wished to demonstrate; that the elderly do present with more difficult lesions and that this plays some role in their poorer outcome. Angiographic follow-up in the elderly population was slightly lower than in the younger group (66% vs. 73%, p = NS); however, a 66% follow-up in this fragile population is a realistic target. Validity of the observed angiographic restenosis rates in the elderly population is supported by the strong correlation between these results, the TLR and the clinical event rate (restenosis 47%, TLR 28% and clinical follow-up event rate of 46%). This study does represent a relatively large nonselected experience from a single center, which provides some insight into the difficulties that exist with revascularization and stent implantation in the elderly population.
Conclusions. Elderly patients who undergo coronary artery stenting have significantly more procedural complications and worse 6-month outcome than younger patients. This is in part due to presentation of the elderly with significantly more three-vessel coronary artery disease, unstable angina, complex lesions and lower ejection fractions. The subgroup of elderly patients with poorest outcome had significantly higher rates of these combined risk factors, including prior MI. Overall long-term survival after coronary artery stenting in the elderly is 91% at 1 year but event free survival is only 54%. There have been considerable gains made in the past 10 years in the treatment of coronary artery disease in the elderly; however, despite technological advances with improvements in revascularization equipment, increased operator experience, procedural modifications and stent technology, procedural complications and adverse cardiac events during follow-up are significantly higher in older patients. Further improvements are necessary to optimize the results in this high-risk group.
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