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Original Articles |
From the Department of Cardiology (D.G.K.), Athens Euroclinic, Athens, Greece; the Clinical Trials and Evidence-Based Medicine Unit (G.C.M.S., J.P.A.I.), Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, Ioannina, Greece; the Biomedical Research Institute (J.P.A.I.), Foundation for Research and Technology-Hellas, Ioannina, Greece; and the Institute for Clinical Research and Health Policy Studies (J.P.A.I.), Tufts Medical Center and Department of Medicine, Tufts University School of Medicine, Boston, Mass.
Correspondence to John P.A. Ioannidis, MD, Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, Ioannina 45110, Greece. E-mail jioannid{at}cc.uoi.gr
Received March 24, 2009; accepted July 22, 2009.
| Abstract |
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Methods and Results— We have conducted a meta-analysis of randomized trials including patients with coronary bifurcation lesions who were randomly selected to undergo percutaneous coronary intervention by either double or single stenting. Six studies (n=1642 patients) were eligible. There was increased risk of myocardial infarction with double stenting (risk ratio, 1.78; P=0.001 by fixed effects; risk ratio, 1.49 with Bayesian meta-analysis). The summary point estimate suggested also an increased risk of stent thrombosis with double stenting, but the difference was not nominally significant given the sparse data (risk ratio, 1.85; P=0.19). No obvious difference was seen for death (risk ratio, 0.81; P=0.66) and target lesion revascularization (risk ratio, 1.09; P=0.67).
Conclusions— Stenting of both the main vessel and side branch in bifurcation lesions may increase myocardial infarction and stent thrombosis risk compared with stenting of the main vessel only.
Key Words: angioplasty coronary bifurcation PCI stents meta-analysis
| Introduction |
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Clinical Perspective on p 409
| Methods |
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Data Extraction
All data were extracted independently by 2 evaluators (D.G.K. and G.C.M.S.) and discrepancies were resolved by a third evaluator (J.P.A.I.). From each eligible study, we recorded information regarding the number of patients that were randomly assigned to 1 of the 2 stenting strategies based on the intention-to-treat analysis and patient demographics (mean age, proportion of male patients, major cardiovascular risk factors, history of myocardial infarction, prior PCI or coronary artery bypass graft surgery, prevalence of angina symptoms, and mean left ventricular ejection fraction). Furthermore, we extracted data on crossover rates; percentages of true bifurcations (when not given by the authors, we defined true bifurcations as Medina 1,1,1 or 1,0,1 or 0,1,1 and Lefevre 1 or 4)15; procedural parameters (type of complex stenting technique, type of drug-eluting stent, use of glycoprotein IIb/IIIa inhibitors, implementation of final "kissing balloon" inflation); measurements that derived from the quantitative coronary angiography analysis (minimum lumen diameter, diameter stenosis, lesion length) and the location of the bifurcation lesions.
The following major outcomes were extracted: death from any cause, myocardial infarction (Q wave and non-Q wave), stent thrombosis, and target lesion revascularization.
We considered the longest available follow-up period for all events in each eligible study. For stent thromobosis, the criteria used in each individual eligible study were adopted. Myocardial infarction was defined by ECG changes and elevation of myocardial enzymes. In cases that the events in each intervention group were analyzed based on the finally implemented treatment and not according to the intention-to-treat approach, we contacted the corresponding authors to provide us the intention-to-treat data.
Statistical Analysis
Categorical data are summarized as frequencies and percentages, whereas summary statistics for continuous variables are presented as means and SDs. For meta-analyses, the risk ratio was used as the metric of choice, and we also performed analyses using the risk difference metric. Between-study heterogeneity was evaluated with the
2 test-based Q statistic and was considered statistically significant at a level of <0.10. We further quantified the effect of the heterogeneity across studies using the I2 statistic, which is independent of the number of studies16,17 and obtained its 95% CIs.18 Fixed effects models with studies weighted by the inverse of their variance and random effects models using the DerSimonian and Laird method were used to combine the data across studies.19 When there is no detectable between-study heterogeneity, the 2 models give identical results. In the presence of detectable between-study heterogeneity, random effects give wider CIs.
For meta-analysis results that were nominally statistically significant by both fixed and random effects, we also performed a sensitivity analysis using a Bayesian meta-analysis model for the risk ratio. This approach generates a posterior distribution of the effect size and 95% credibility, as opposed to CIs generated by traditional frequentist meta-analysis. We used the WinBUGS software20 (Imperial College and MRC, London) and estimated the posterior of the effect size using 20 000 iterations after a 10 000 iteration initial burn-in. Bayesian inference is more appropriate for making probabilistic inferences about the magnitude of the treatment effect and the variability that it may have in different populations that are similar to the ones studied in the randomized trials whose data are combined.
Statistical analyses were conducted in Stata 10.0 (Stata Corp, College Station, Tex) and WinBUGS software. P values are 2 tailed.
| Results |
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Patients, Demographic, and Procedural Characteristics
Demographic characteristics of the included patients and procedural details of the implemented PCI technique are shown in Tables 1 through 3![]()
. A total of 1642 patients were included (821 in each intervention arm). Patient populations mean age ranged from 60 to 67 years, whereas women comprised 20% to 23% of the study populations. The proportion of diabetic patients ranged from 12% to 41% (Table 1). In 4 studies,8–11 patients that presented with myocardial infarction in the last 24 hours were excluded. Moreover, reduced left ventricular function (ejection fraction <35%) was an exclusion criterion in CACTUS8 and Colombo et al9 Some patients with myocardial infarction were included only in BBC ONE (21% of the study population).7 The definition of myocardial infarction (Q wave and non-Q wave) differs among the included studies, as shown in Table 2.
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In 5 of the 6 studies, information regarding quantitative coronary measurements (minimum lumen diameter, diameter stenosis, and the length of lesion) pre-PCI, post-PCI, and at follow-up were available for each group as shown in supplemental Table I. The most common location of the treated bifurcation lesions across the studies were the left anterior descending/diagonal artery (in 76% of all cases in both arms), whereas bifurcation lesions that included the left main stem were stented only in 13 cases in 2 of the studies (supplemental Table I).
Outcome Events and Data Synthesis
The incidence of the main outcomes across the eligible studies is shown in Table 4. Death occurred in 18 patients (simple strategy n=10 versus complex strategy n=8). In total, 144 patients were reported to have myocardial infarction (simple strategy n=51 versus complex strategy n=93), and 21 events of definite stent thrombosis were recorded (simple strategy n=7 versus complex strategy n=14). Target lesion revascularization was performed in 88 cases (simple strategy n=42 versus complex strategy n=46).
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Inferences were similar in the risk difference scale, with the exception that there was statistically significant between-study heterogeneity for the myocardial infarction outcome. Point estimates suggested approximately a 3% excess risk of myocardial infarction and 1% excess risk of stent thrombosis with the double-stent versus single-stent approach.
| Discussion |
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The introduction of drug-eluting stents in the treatment of bifurcation lesions has been thought to improve operational outcomes and decrease the need for restenosis and revascularization. In the Arterial Revascularization Therapies Study II, event rates were similar in bifurcation and nonbifurcation lesions.21 Erglis et al22 from the NORDIC group also showed that stenting of both bifurcation branches with either the cullote or the crush techniques yielded relatively low restenosis rates. These results, however, were drawn following 6 months clinical and 8 months angiographic follow-up, which is rather inadequate for definitive conclusions about the long-term clinical outcomes of this approach. A previous systematic review14 that did not include 3 recent randomized trials had found no demonstrable differences between the 2 strategies, but the 3 latest studies show an inferiority of double stenting in terms of the risk of myocardial infarction and possibly also stent thrombosis in particular. All studies used drug-eluting stents and modern techniques. The absolute excess risk (in the range of 3 for myocardial infarction) is considerable.
Our findings indicate that double stenting of a bifurcation lesion is not advantageous and seems also to have a detrimental impact on major clinical outcomes. They also suggest that current practices for bifurcation lesions need careful reexamination. For example, in a recent statement by the European Bifurcation Club, complex treatment strategies are discussed and the evidence in favor of the simple strategy is ignored.23 Of course, in clinical practice, complex stenting is often inevitable, especially in the case of a true bifurcated lesion with a massive plaque burden and a side branch of considerable size. However, the angiographic appearance of ostial residual stenosis of a side branch does not correspond to its functional significance, and in most cases, kissing balloon dilatation may suffice.24 The prognosis of jailed side branches is favorable. Dissected or even occluded side branches are usually clinically silent and probably do not affect long-term clinical event-free survival.13,25,26 The majority of side branches (up to 90%) reappear at follow-up.25 Furthermore, complex stenting strategies at bifurcation sites have been identified as predictors of stent thrombosis. Overall, PCI with stenting does not seem to improve death or myocardial infarction rates as compared with optimized medical therapy alone in chronic stable coronary artery disease.27,28 For bifurcation lesions, using 2 stents rather than 1 seems to result even in worse outcomes.
Some caveats should be discussed. First, some of the studies had considerable crossover rates. In particular, Colombo et al9 have reported a crossover rate as high as 51.2% in their study evaluating sirolimus-eluting stents implanted in coronary bifurcation lesions. A high crossover rate may be due to an angiographically unsatisfactory postangioplasty result. Therefore, what the meta-analysis evaluates is the original intention: whether it is better to try to place a single stent or 2. Second, the design of analyzed trials, background profiles of the studied populations, rates of use of adjunctive IIB/IIIA glycoprotein inhibitors, and techniques used to perform double stenting were different between studies. This may need to be considered in the generalization of our conclusions, but we found no strong evidence for between-study heterogeneity in the treatment effects in the risk ratio scale. These sources of diversity should not preclude synthesizing the results using meta-analysis and drawing useful inferences from the meta-analysis.29 Finally, we did not address in this meta-analysis the impact of double versus single stenting on angiographic outcomes. The reported success rates of double stenting in trials are high, and this approach results in good immediate angiographic outcomes. This, however, does not translate in reduced mortality, myocardial infarction, or revascularization rates. The financial burden may also be considerable.
In conclusion, acknowledging these caveats, the current meta-analysis indicates that stenting of both the main and side branches of a bifurcation lesion may be associated with considerable excess risk of myocardial infarction and possible excess risk of stent thrombosis. Our study suggests that double stenting of both the main vessel and the side branch vessel in bifurcation lesions should be avoided. Perhaps double stenting could be considered in cases of a very big bifurcation branch, such as main stem lesions or lesions involving bifurcation branches with diameter almost as big as that of the main branch. However, no convincing data exist in this context. Further studies are needed to define the optimum treatment of bifurcation lesions in the era of changing indications for coronary intervention.
| Acknowledgments |
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Disclosures
Dr Katritsis is an interventional cardiologist and receives research grants from Boston Scientific and Johnson & Johnson.
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