CLINICAL STUDY
Early angioplasty in acute coronary syndromes without persistent st-segment elevation improves outcome but increases the need for six-month repeat revascularization
An analysis of the pursuit trial
Eelko Ronner, MD, PhD* ,
Eric Boersma, PhD*,
Gert-Jan Laarman, MD, PhD,
G. Aernout Somsen, MD, PhD ,
Robert A. Harrington, MD, PhD ,
Jaap W. Deckers, MD, PhD*,
Eric J. Topol, MD, PhD||,
Robert M. Califf, MD, PhD and
Maarten L. Simoons, MD, PhD*,*
* University Hospital Rotterdam, Rotterdam, The Netherlands
Onze Lieve Vrouwe Gasthuis, Amsterdam, The Netherlands
Academic Medical Center, Amsterdam, The Netherlands
Duke Clinical Research Institute, Durham, North Carolina, USA
|| Cleveland Clinic Foundation, Cleveland, Ohio, USA
Manuscript received September 5, 2001;
revised manuscript received March 5, 2002,
accepted March 27, 2002.
* Reprint requests and correspondence: Dr. Maarten L. Simoons, Thoraxcenter, H560, Academisch Ziekenhuis Rotterdam, Dijkzigt, Dr Molewaterplein 40, 3015 GD Rotterdam, The Netherlands.
simoons{at}tch.fgg.eur.nl
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Abstract
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OBJECTIVES: We explored the effect of timing of percutaneous coronary intervention (PCI) in acute coronary syndromes (ACS) without persistent ST-segment elevation on the need for repeat revascularization, and we related this effect to other events.
BACKGROUND: Percutaneous coronary intervention is widely used to treat ACS without persistent ST-segment elevation. Moreover, restenosis and subsequent revascularization after PCI are more frequent in ACS than in stable angina. The optimal timing of PCI in ACS without persistent ST-segment elevation is unknown.
METHODS: In the Platelet glycoprotein IIb/IIIa in Unstable angina: Receptor Suppression Using Integrilin Therapy (PURSUIT) database, patients were stratified by the time of PCI. In the PURSUIT trial, 9,461 patients received a platelet glycoprotein IIb/IIIa inhibitor, eptifibatide or placebo for 72 h. The investigators decided on other treatments.
RESULTS: A total of 2,430 patients underwent PCI within 30 days. Repeat revascularization (during 165 days) was notably higher for PCI within 24 h of enrollment (n = 620 [19%]) than for PCI at 24 to 72 h (n = 624 [16.7%]), 3 to 7 days (n = 614 [13.2%]), or 8 to 30 days (n = 561 [7.7%]; p < 0.001), regardless of eptifibatide use. This gradual reduction in the revascularization rate for later PCI was also observed after multivariate analysis correcting for baseline characteristics and with time as a continuous variable.
CONCLUSIONS: Percutaneous coronary intervention within 24 is associated with improved outcome (other analysis) but more repeat revascularization. Prospective analyses are needed to test the hypothesis that rapid PCI in ACS with a platelet glycoprotein IIb/IIIa receptor antagonist reduces myocardial infarction (and possibly death) and is therefore most suited for patients at highest risk of infarction, despite a higher need for repeat revascularization.
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Abbreviations and Acronyms
| | ACS | | acute coronary syndromes | | CAPTURE | | Chimeric c7E3 AntiPlatelet Therapy in Unstable angina REfractory to standard treatment trial | | CK-MB | | creatine kinase, MB fraction | | FRISC | | FRagmin during InStability in Coronary artery disease | | GP | | glycoprotein | | MI | | myocardial infarction | | PCI | | percutaneous coronary intervention | | PURSUIT | | Platelet glycoprotein IIb/IIIa in Unstable angina: Receptor Suppression Using Integrilin Therapy | | TACTICS/TIMI-18 | | Treat Angina with aggrastat and determine Cost of Therapy with an Invasive or Conservative Strategy/Thrombolysis in Myocardial Infarction trial |
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Percutaneous coronary intervention (PCI) under protection of a platelet glycoprotein (GP) IIb/IIIa receptor inhibitor is a widely adopted treatment strategy for acute coronary syndromes (ACS) without persistent ST-segment elevation. However, the optimal timing of PCI in these patients remains uncertain. The question remains to what extent the patient should be stabilized before the procedure. Recent guidelines suggest a relatively early intervention, especially in high-risk patients with ACS (1,2), after various reports demonstrated a reduction in myocardial infarction (MI) and possibly death for invasively treated versus conservatively treated patients (3,4).
A consequence of PCI, however, is restenosis. There have been reports that restenosis rates with unstable angina are higher than rates with stable angina (5–7), although others demonstrated no difference (8,9). However, the exact relationship between restenosis and the effect of timing of PCI in ACS is largely unknown. Therefore, an analysis of the Platelet glycoprotein IIb/IIIa in Unstable angina: Receptor Suppression Using Integrilin Therapy (PURSUIT) trial (7) was performed to verify the impact of timing of angioplasty on repeat revascularization and long-term outcome in patients with ACS.
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Methods
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Patient population.
The design and methods of PURSUIT have been described previously. In short, patients were enrolled within 24 h of an episode of ischemic chest pain (>10 min) with transient ST-segment elevation (>0.5 mm), transient or persistent ST-segment depression (>0.5 mm), T-wave inversion (>1 mm) or elevation of creatine kinase, MB fraction (CK-MB) above the upper limit of normal. There were no age limits. Eptifibatide or placebo was administered for 72 h, and up to 24 h after PCI, to a maximum of 96 h. Additional treatment, including an intervention, was left entirely to the investigators.
Four patient groups of approximately the same size were compared according to the time of PCI: within 24 h, from 24 to 72 h, from 3 to 7 days and from 8 to 30 days. No systematic follow-up angiography to assess restenosis was performed. Subsequent revascularization was pragmatically defined as any repeat revascularization. In PURSUIT, follow-up after enrollment was six months. In the present analysis, follow-up after PCI was limited to 5.5 months (165 days) after the first PCI to achieve a similar length of follow-up for the different groups of patients.
The primary efficacy end point of PURSUIT was a composite of death or nonfatal MI or recurrent MI at 30 days. Within 18 h of enrollment, MI was diagnosed on the basis of ischemic chest pain and new ST-segment elevation. After 18 h, MI was diagnosed on the basis of new Q waves or new or repeated CK-MB elevations above the upper limit of normal. For patients undergoing PCI, CK-MB elevation above three times the upper limit of normal was required. The end points in this analysis were subsequent revascularization up to 5.5 months after the initial PCI, death and nonfatal MI. In addition, repeat revascularization was described at 30-day follow-up, and thereafter, until 165 days after the initial PCI.
Statistical analysis
In PURSUIT, 2,419 patients underwent PCI within 30 days of enrollment, constituting 26% of the 9,461 patients enrolled. These patients were stratified into four groups according to the timing of the intervention: within 24 h of randomization, at 24 to 72 h, at 3 to 7 days, and at 8 to 30 days. The chi-square test, Student t test and one-way analysis of variance were applied to investigate differences in baseline characteristics between these groups.
Outcomes were evaluated by the chi-square test. Univariate and Cox multivariate logistic regression analyses were applied to describe the relationship between the timing of PCI and the risk of repeat revascularization. All baseline variables from Tables 1 and 2 were included, without deletion of any variable, for final analysis (10). Statistical significance of all tests was set at p = 0.05.
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Results
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Patient population.
The PCI was performed in 620 patients within 24 h, in 624 patients at 24 to 72 h, in 614 patients at 3 to 7 days, and in 561 patients at 8 to 30 days (median 12 days) after enrollment. Significant differences were apparent among these patient groups (Table 1). In particular, more North Americans received PCI within 24 h (82% of all patients treated on day 1) (Table 1), and most procedures (69%) from day 8 to 30 were performed in Western European centers. Hypertension was more frequent in patients treated earlier, as well as in younger patients and those with ST-segment depression at enrollment. Previous PCI was observed more frequently in patients treated earlier. More medication was used in those treated earlier, a finding that reached significance for aspirin and nitrates. As demonstrated in Table 2, more Thrombolysis in Myocardial Infarction (TIMI) flow grades 0 and 1 were observed at angiography before PCI in patients receiving PCI on day 1 versus later. In addition, the culprit lesions were often not determined when multiple lesions were present in the group treated later. Kleiman et al. (11) provide more information on the baseline characteristics and subsequent treatment.
Repeat revascularization
Repeat revascularization was performed in 19% of patients who underwent initial PCI within 24 h, in 16.7% of patients treated with PCI on days 2 and 3, in 13.2% of those treated on days 4 to 7, and in 7.7% of those treated on days 7 to 30 (p = 0.001) (Fig. 1).
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Figure 1 Death and myocardial infarction at 30 days, according to the time of percutaneous coronary intervention (PCI).
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Univariate and multivariate analyses confirmed the predictive value of the timing of initial PCI on the frequency of repeat revascularization. Using the timing of PCI as either a continuous or categorical variable, the p value in this analysis was <0.0005. From Figure 2, it is evident that most repeat revascularization occurred early. Geographic region was not related to the repeat revascularization rate on multivariate analysis.
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Figure 2 Occurrence (%) of cardiac complications in patients undergoing percutaneous coronary intervention from day 0 to 30, randomly assigned to glycoprotein IIb/IIIa inhibition (open bars) or placebo (solid bars) for 72 h. MI = myocardial infarction.
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Early and late repeat revascularization
In separate analyses of repeat revascularization within or after 30 days, both early and late repeat revascularization were found to be related to the timing of the initial PCI, independent of other baseline characteristics (Fig 2). In patients randomized to placebo, the 30-day repeat revascularization rate was 13.7% when the initial PCI was performed on day 1, 11.4% for PCI performed on day 2 or 3, 8.3% for PCI on days 4 to 7, and 5.2% after seven days of enrollment in PURSUIT (p = 0.002). For eptifibatide-treated patients, the 30-day repeat revascularization rate did not demonstrate this highly significant trend. Repeat revascularization in eptifibatide-treated patients was observed in 10.8% of patients who underwent PCI on day 1, 8.7% of those who underwent PCI on day 2 or 3, and 9.1% of those who underwent PCI on days 4 to 7, respectively, and 6.3% of those in whom the initial PCI was performed after seven days (p = 0.304).
"Late" repeat revascularization after one month of initial PCI up to 165 days of follow-up was significantly dependent on the timing of initial PCI. This held true for both placebo- and eptifibatide-treated patients. There was a significant decrease in the repeat revascularization rate when PCI was performed later: 6.8% for all patients who underwent PCI within one day of enrollment in PURSUIT, down to 2% for patients who had PCI after one week (p < 0.001). In particular, patients undergoing PCI on day 2 or 3, treated with eptifibatide, demonstrated repeat revascularization in this retrospective analysis.
Mortality and MI
The occurrence of MI and death was clearly influenced by the timing of PCI in patients treated with eptifibatide, as addressed in a separate report (12). Early PCI, within 24 h, under protection of a platelet GP IIb/IIIa receptor antagonist, was associated with a favorable 30-day outcome of 9.2%, compared with 14.0% to 17.4% for later PCIs (Fig. 2).
In placebo-treated patients, death and MI at 30 days ranged from 15.9% for PCI within 24 h to 17.7% for PCI at 24 to 72 h, to 15.0% for PCI on days 4 to 7, and 17.4% for PCI on days 8 to 30. In placebo-treated patients, no relationship between the timing of PCI and MI or mortality was apparent. Early procedures in placebo-treated patients were associated with higher procedural event rates, which balanced the reduction in subsequent post-procedural death and MI (Fig. 2).
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Discussion
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This retrospective analysis of the PURSUIT trial demonstrated an improved outcome (fewer MIs) in patients undergoing PCI within 24 h of enrollment but a reduction in repeat revascularization after "cooling down" or deferred PCI. Revascularization rates were reduced from 27% for PCI on day 1 to 18% for PCI after one week (median 12 days). It should be appreciated that we addressed "repeat revascularization." This term includes lesions treated for not merely restenosis, but also other coronary lesions in need of revascularization. Within six months, however, repeat revascularization is needed to treat restenosis in a vast majority of patients.
The timing of PCI was a highly significant determinant of repeat revascularization in univariate and multivariate analyses. To explain this finding, it is important to note that increased revascularization rates in patients undergoing early PCI are demonstrated for repeat revascularization occurring within a short period (within 1 month) and during longer-term follow-up (from 1 month to 5.5 months).
Early versus late repeat revascularization.
Early (within 1 month of PCI) repeat revascularization is conceivably needed mainly for thrombotic complications alone or in combination with elastic recoil (13,14). This thrombotic component of early revascularization is perhaps antagonized by eptifibatide. In patients receiving a platelet GP IIb/IIIa receptor blocker in acute MI, in addition to primary PCI, this reduction in urgent revascularization is well known (15).
In late restenosis, intimal hyperplasia is the key determinant. Intervention in a vessel after stabilization of disease and plaque leads to a smaller inflammatory response, with less intimal proliferation and, subsequently, less development of restenosis and less need for (late) repeat revascularization (16).
C-reactive protein
A similar relationship between the disease state or vessel pacification and the likelihood of developing restenosis is demonstrated by a number of reports on C-reactive protein. This acute-phase protein is a general inflammation marker and is associated with the progression of atherosclerosis and severity of ACS, without persistent ST-segment elevation, as demonstrated in a number of large clinical trials, such as FRagmin during InStability in Coronary artery disease (FRISC) and Chimeric c7E3 AntiPlatelet Therapy in Unstable angina REfractory to standard treatment trial (CAPTURE) (17–19). Just as we demonstrated for the time since presentation with ACS without persistent ST-segment elevation, elevated C-reactive protein proved to be a predictor for repeat revascularization (20). Likewise, post-procedural C-reactive protein elevation after PCI was demonstrated to relate to repeat revascularization. Another report demonstrated that patients with higher pre-procedural C-reactive protein react to PCI with a higher procedural rise in C-reactive protein (21).
This might provide some insight as to why deferring PCI in patients with ACS without persistent ST-segment elevation reduces the risk of repeat revascularization, because not only is the pre-procedural risk of repeat revascularization reduced, but also the procedural development of C-reactive protein elevation (and presumably the risk of repeat revascularization) is reduced by deferral.
Early PCI versus delayed PCI and conservative treatment
Vessel pacification by deferring PCI seems an attractive alternative, with respect to repeat revascularization. However, "cooling down" of ACS before PCI may be unfavorable, with respect to 30-day MI and possibly death. In a number of recent trials and PURSUIT sub-analyses, the benefit of intervention over conservative treatment is demonstrated (Fig. 2) (4,22,23). For example, the recently published FRISC-2 trial demonstrated a benefit of intervention versus conservative treatment. Intervention was performed on day 4 (median) (3). The six-month death and MI rate was 9.4% for intervention versus 12.1% for conservatively treated patients (p = 0.03). In this trial, in 10% of patients platelet GP IIb/IIIa receptor antagonists were administered in both the invasive and conservative arm. The mean time of PCI was day 4. Another recently reported trial, the Treat Angina with aggrastat and determine Cost of Therapy with an Invasive or Conservative Strategy (TACTICS/TIMI-18) trial, demonstrated a benefit of the early invasive strategy (n = 1,114), compared with medical management (n = 1,106) (4). Significantly, a lower rate of 30-day death and MI was observed in the early invasive arm (4.7%), compared with the conservative arm (7.0%).
Not surprisingly, current European and U.S. guidelines for the treatment of ACS recommend rapid PCI under the protection of a platelet GP IIb/IIIa receptor antagonist in high-risk patients (1,2). However, neither guideline states how rapid this should be. Our recent PURSUIT report on the timing of PCI demonstrated a 9.2% 30-day death and MI rate for patients receiving PCI on day 1 with eptifibatide, compared with event rates of 14.0% to 18.2% for other groups with and without PCI and eptifibatide (p < 0.001) (12).
Our finding of increased repeat revascularization in patients in whom PCI was performed early offsets the benefit of a reduction in MI seen with rapid PCI, but, in our opinion, does not influence the treatment of highest-risk patients. We postulate that highest risk patients are best treated with rapid PCI to prevent MI, at the possible cost of more revascularizations. Although only indirectly demonstrated by our analysis, it is possible that low-risk patients benefit from "watchful waiting," as infarcts are unlikely to occur, and repeat revascularization can be avoided.
Study limitations
It is emphasized that a retrospective analysis of data can be misleading. A particular limitation of this specific analysis is the lack of detailed angiographic data in the PURSUIT trial. Most notably, lesion characteristics that predict restenosis (e.g., length, calcification and tortuosity of the lesion) were not recorded. It is possible that adverse angiographic revascularization predictors were not evenly spread among the groups. In light of this, it is interesting to note that the use of stents ( 50% in all groups) was not related to the rate of repeat revascularization. This may be explained by the selection of patients with angiographic lesions with high risk of revascularization in stented patients more than balloon-treated patients. Elective versus bailout stenting was not specifically recorded, and this could constitute another explanation.
Conclusions
A clear inverse relationship was demonstrated between the time of PCI and the subsequent need for repeat revascularization within 5.5 months. Although retrospective, this decrease in repeat revascularization with later PCI was confirmed by multivariate analysis.
In the treatment of ACS, as seen in the PURSUIT trial retrospectively, there seems to be a tradeoff in the timing of PCI. There is a benefit of deferred PCI with respect to the need for repeat revascularization; however, there seems to be a negative effect of deferred PCI with respect to MI and possibly death and the costs of treatment.
Current recommendations to intervene early under the protection of a platelet GP IIb/IIIa receptor antagonist are clear for high-risk patients. For other groups the issue remains unresolved. If the chances of developing MI are low, "watchful waiting" and performing PCI when symptoms or ischemia recurs seem attractive. It should be emphasized, however, that prospective studies are needed to verify these findings.
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Footnotes
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The PURSUIT trial was supported by COR Therapeutics, Inc., South San Francisco, California, and the Schering-Plough Research Institute, Kenilworth, New Jersey.
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References
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Abstract
Methods