Intravascular ultrasound (IVUS) offers tomographic images of the coronary artery, helping physicians to refine drug-eluting stent (DES) implantation in angiographically complex lesions. However, controversy exists regarding whether the routine use of IVUS in short-length lesions leads to improved clinical outcomes after DES implantation. Therefore, we evaluated the usefulness of IVUS in predicting major adverse cardiac events (MACE), including cardiovascular death, myocardial infarction, or target vessel revascularization, at 1 year after DES implantation in short-length lesions. The present study was a subanalysis of the REal Safety and Efficacy of a 3-month dual antiplatelet Therapy following Endeavor zotarolimus-eluting stent implantation (RESET) study with different clinical outcome parameters. The study population consisted of 662 patients with IVUS guidance and 912 patients with angiography guidance who underwent DES implantation (stent length ≤24 mm). In the IVUS-guided group, adjuvant postdilation was more frequently performed (43.0% vs 34.6%, p <0.001), and the postintervention minimal lumen diameters were greater (2.88 ± 0.44 mm vs 2.72 ± 0.43 mm, p <0.001). MACE occurred in 15 IVUS-guided (2.3%) and 19 angiographically guided (2.1%) patients (p = 0.872). In a subset of patients with diabetes mellitus (n = 292), the MACE rate was 3.4% (n = 4) and 1.7% (n = 3) in the IVUS- and angiographically guided patients, respectively (p = 0.384). The MACE rate in the IVUS- and angiographically guided patients with acute coronary syndrome (n = 601) was 1.1% (n = 3) and 2.7% (n = 9), respectively (p = 0.194). The clinical benefits of IVUS-guided DES implantation compared with angiographically guided DES implantation in short-length lesions could not be confirmed even in patients with clinically high-risk presentations (acute coronary syndrome and diabetes mellitus). In conclusion, routine IVUS guidance does not provide clinical benefits when performing short-length DES implantation.
Intravascular ultrasound (IVUS) provides useful information for percutaneous coronary intervention (PCI) procedures, such as edge dissection and stent underexpansion or malapposition, and tomographic assessment of the coronary artery, including the vessel and lumen area, plaque size, and plaque characteristics. In the bare metal stent era, the utility of IVUS was relatively clear-cut. However, with the advent of the drug-eluting stent (DES), the usefulness of IVUS in PCI procedures has become controversial. It has been shown to be clinically beneficial in registry data with large numbers of patients and propensity score analysis. However, no clinical benefit was seen in randomized studies with small numbers of patients. Recent studies have reported the benefits of IVUS in a subset of angiographically complex lesions of the left main artery, bifurcation lesions, and long lesions. However, the utility of IVUS in angiographically simple lesions (i.e., short-length lesions) has been debated, and it is unknown whether the routine use of IVUS is of practical value in performing DES implantation in such lesions. Therefore, we compared the results of IVUS-guided PCI with those of angiographically guided PCI in short-length lesions treated with DESs (≤24 mm in length) in a subanalysis of the REal Safety and Efficacy of a 3-month dual antiplatelet Therapy following Endeavor zotarolimus-eluting stent implantation (RESET) trial.
Methods
The RESET trial was a prospective, randomized, multicenter trial to demonstrate the noninferiority of 3-month dual antiplatelet therapy after Endeavor zotarolimus-eluting stent (Endeavor Sprint, Medtronic, Santa Rosa, California) implantation compared with 12-month dual antiplatelet therapy after implantation with other DESs. The study participants were randomly assigned in a 1:1 ratio to receive either the Endeavor zotarolimus-eluting stent (Endeavor Sprint) or another currently available DES. Randomization was stratified by participating center and 4 clinical or lesion characteristics: diabetes mellitus (n = 292 patients), acute coronary syndrome (n = 601 patients), treatment of a short lesion (stent length ≤24 mm; n = 681 patients), and treatment of a long lesion (stent length ≥28 mm; n = 543 patients). In the long-length DES subset, patients had a de novo lesion requiring a stent ≥28 mm in length in a vessel. In the other 3 subsets, the 1,574 remaining patients had a de novo lesion requiring a stent ≤24 mm in length in a vessel with a distal reference diameter of ≥2.5 mm by visual angiographic estimation. The use of IVUS was at the discretion of the operator; therefore, the patients were grouped according to the use of IVUS during PCI: IVUS-guided group (n = 662) versus angiographically guided group (n = 912). Details of the inclusion and exclusion criteria were described in the previous study. Those patients with left main disease requiring PCI, bifurcation lesions treated with a 2-stent technique, chronic total occlusions, or a history of PCI with DESs were also excluded in the previous study. Therefore, the morphology of the target lesions in the present study were angiographically simple and of short length. The institutional review board at each participating institution approved the study protocol, and all patients provided written consent. The ClinicalTrials.gov identifier was NCT01145079 .
DES implantation was performed according to standard techniques. In the angiographically guided group, the stent size and length were chosen by visual estimation, and adjuvant high-pressure dilation was performed if an optimal result was not achieved. An optimal result was defined as an angiographically residual diameter stenosis of <10% and the absence of angiographically detected dissection. In the IVUS-guided group, the final stent size and length were determined by on-line IVUS measurements, and adjuvant high-pressure dilation was performed at the discretion of the operator according to the IVUS findings. We used 1 of 2 commercially available IVUS systems (Atlantis S or I-Lab, Boston Scientific Scimed, Maple Grove, Minnesota) or Eagle Eye (Volcano Therapeutics, Rancho Cordova, California) was used. The details of the pre- and post-PCI dual antiplatelet therapy and quantitative coronary angiographic analysis were described in the previous study.
Postprocedure clinical assessments were performed in-hospital and after 1, 3, 6, and 12 months by either clinic visit or telephone interview. The occurrence of major adverse cardiovascular events (MACE), including cardiovascular death, myocardial infarction, and target vessel revascularization, at 1 year after procedure was compared between the 2 groups. Clinical events were defined according to the Academic Research Consortium. All deaths were considered cardiovascular deaths unless a definite noncardiovascular cause was established. Myocardial infarction was defined as the presence of clinical symptoms, electrocardiographic changes, or abnormal imaging findings of myocardial infarction combined with an increase in the creatine kinase-MB fraction >3 times the upper limit of the normal range or an increase in troponin T or troponin I to more than the 99th percentile of the upper normal limit, all of which were unrelated to the interventional procedure. Stent thrombosis was defined according to the recommendations of the Academic Research Consortium. Target vessel revascularization was defined as repeat PCI or bypass surgery of the target vessel with either (1) ischemic symptoms or positive stress test findings and angiographic diameter stenosis ≥50% by quantitative coronary angiographic analysis; or (2) angiographic diameter stenosis of ≥70% using by quantitative coronary angiographic analysis without ischemic symptoms or positive stress test findings.
Continuous variables are expressed as the mean ± SD and categorical variables as numbers and percentages. Statistical analysis was performed using the Statistical Package for Social Sciences, version 20.0 (IBM, Armonk, New York). The categorical variables were compared using chi-square statistics and Fisher’s exact test. Student’s t test was used to compare the continuous, normally distributed variables; otherwise, the Mann-Whitney U test was used. Relative risks with 95% confidence intervals were calculated to compare the proportions of clinical events. Event-free survival was determined using Kaplan-Meier survival curves and compared using the log-rank test. A p value <0.05 was considered statistically significant.
Results
No statistically significant differences in the baseline clinical characteristics were found between the 2 groups, except that the patients were younger in the IVUS-guided group (61.2 ± 9.4 vs 62.6 ± 9.9 years; Table 1 ). The angiographic and procedural findings are listed in Table 2 . Treatment on the left anterior descending artery was more frequently performed in the IVUS-guided group. Multivessel intervention was more frequently observed in the angiographically guided group. The reference vessel diameter and pre- and postintervention minimal lumen diameters were larger in the IVUS-guided group. Adjuvant postdilation was also more frequently performed in the IVUS-guided group (43.0% vs 34.6%, p <0.001). The clinical outcomes through 1 year of follow-up are summarized in Table 3 . MACE occurred in 15 patients (2.3%) in the IVUS-guided group and 19 patients (2.1%) in the angiographically guided group (p = 0.872). In the subset of patients with diabetes mellitus (n = 292), the MACE rate was 3.4% (n = 4) and 1.7% (n = 3) for the IVUS- and angiographically guided patients, respectively (p = 0.384). The MACE rate in IVUS- and angiographically guided patients with acute coronary syndrome (n = 601) was 1.1% (n = 3) and 2.7% (n = 9), respectively (p = 0.194). In a subset of patients with short-length DESs (n = 681), the MACE rate was 2.8% (n = 8) and 1.8% (n = 7) in the IVUS-guided and angiographically guided patients, respectively (p = 0.397). No significant differences were found in the angiographic or procedural variables in patients with versus without MACE ( Table 4 ). The results of the Kaplan-Meier survival curve analysis did not indicate a benefit for IVUS at 1 year of follow-up (log-rank test, p = 0.872; Figure 1 ).
| Variable | IVUS Guided (n = 662) | Angiographically Guided (n = 912) | p Value |
|---|---|---|---|
| Age (yrs) | 61.2 ± 9.4 | 62.6 ± 9.9 | 0.005 |
| Men | 428 (64.7) | 592 (64.9) | 0.915 |
| Hypertension ∗ | 397 (60.0) | 570 (62.5) | 0.309 |
| Diabetes mellitus | 184 (27.8) | 270 (29.6) | 0.468 |
| Dyslipidemia (total cholesterol ≥200 mg/dl) | 403 (60.9) | 512 (56.1) | 0.064 |
| Current smoker | 167 (25.2) | 236 (25.9) | 0.815 |
| Previous myocardial infarction | 7 (1.1) | 18 (2.0) | 0.220 |
| Previous PCI | 22 (3.3) | 27 (3.0) | 0.682 |
| Clinical presentation | 0.08 | ||
| Stable angina pectoris | 267 (40.3) | 410 (45.0) | |
| Acute coronary syndrome | 395 (59.7) | 502 (55.0) | |
| Multivessel coronary disease | 298 (45.0) | 406 (44.5) | 0.885 |
| Dual antiplatelet therapy duration (days) | 234.6 ± 132.2 | 241.9 ± 132.7 | 0.424 |
| Variable | IVUS Guided (n = 735) | Angiographically Guided (n = 1,165) | p Value |
|---|---|---|---|
| Treated coronary artery | <0.001 | ||
| Left anterior descending | 441 (60.0) | 566 (48.6) | |
| Left circumflex | 131 (17.8) | 255 (21.9) | |
| Right coronary | 163 (22.2) | 344 (29.5) | |
| Type of drug eluting stent | 0.694 | ||
| Endeavor zotarolimus-eluting stents | 376 (51.2) | 582 (50.0) | |
| Cypher sirolimus-eluting stents | 151 (20.6) | 232 (19.9) | |
| Resolute zotarolimus-eluting stents | 208 (28.3) | 351 (30.1) | |
| Multivessel coronary intervention per patient | 97 (14.7) | 172 (18.9) | 0.029 |
| Lesion length (mm) | 16.6 ± 6.6 | 15.8 ± 5.9 | 0.009 |
| Stent length per lesion (mm) | 20.4 ± 5.1 | 20.1 ± 7.0 | 0.313 |
| Adjuvant postdilation | 316 (43.0) | 403 (34.6) | <0.001 |
| Maximum inflation pressure (atm) | 16.7 ± 3.4 | 16.1 ± 3.8 | 0.061 |
| Reference vessel diameter (mm) | 3.12 ± 0.48 | 3.02 ± 0.48 | <0.001 |
| Preintervention minimum luminal diameter (mm) | 1.17 ± 0.48 | 1.02 ± 0.48 | <0.001 |
| Postintervention minimum lumen diameter (mm) | 2.88 ± 0.44 | 2.72 ± 0.43 | <0.001 |
| Variable | IVUS Guided (n = 662) | Angiographically Guided (n = 912) | HR (95% CI) | p Value |
|---|---|---|---|---|
| Death from any cause | 1 (0.2) | 7 (0.8) | 0.19 (0.02–1.55) | 0.122 |
| Cardiovascular death | 1 (0.2) | 4 (0.4) | 0.34 (0.04–3.06) | 0.342 |
| Myocardial infarction | 1 (0.2) | 3 (0.3) | 0.45 (0.05–4.36) | 0.453 |
| Target vessel revascularization | 14 (2.1) | 14 (1.5) | 1.34 (0.64–2.80) | 0.445 |
| Stent thrombosis | 1 (0.2) | 2 (0.2) | 0.68 (0.06–7.52) | 0.754 |
| Cardiovascular death or myocardial infarction | 2 (0.3) | 6 (0.7) | 0.46 (0.09–2.25) | 0.335 |
| Cardiovascular death, myocardial infarction, or target vessel revascularization | 15 (2.3) | 19 (2.1) | 1.06 (0.54–2.08) | 0.872 |
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