CORRESPONDENCE: RESEARCH CORRESPONDENCE
New Stent Implantation for Recurrences After Stenting for In-Stent RestenosisImplications of a Third Metal Layer in Human Coronary Arteries
Fernando Alfonso, MD*,
Javier García, MD,
Maria-José Pérez-Vizcayno, MD,
Lorenzo Hernando, MD,
Rosana Hernandez, MD,
Javier Escaned, MD,
Pilar Jiménez-Quevedo, MD,
Camino Bañuelos, MD and
Carlos Macaya, MD
* Instituto Cardiovascular, Hospital Universitario Clínico "San Carlos", Plaza de Cristo Rey, Madrid 28040, Spain (Email: falf{at}hotmail.com).
Key Words: in-stent restenosis • drug-eluting stents • repeat stenting • intravascular ultrasound
To the Editor:
Treatment of in-stent restenosis (ISR) remains a challenge (1–5). Bare-metal stents provide excellent angiographic results, but are shadowed by high restenosis rates. Accordingly, they are reserved for patients with large vessels, edge-ISR, or those unsuitable for long-term dual antiplatelet therapy (1–3). Currently, drug-eluting stents (DES) represent the therapy of choice for ISR (2,3). Nevertheless, 10% to 20% of patients receiving DES for ISR develop recurrences (2,3). The best management for patients with recurrent ISR in a segment previously treated with 2 stents remains unsettled. Furthermore, the pathophysiological consequences of a third metal layer on human coronary arteries are unknown. We describe the long-term clinical, angiographic, and intravascular ultrasound (IVUS) results of a new stent implantation in patients suffering recurrences after stenting for ISR.
From April 2004 to June 2008, 21 consecutive patients undergoing stent implantation for recurrent ISR after stenting for ISR (third stent on the same coronary segment) were included. The study protocol was approved by the Institutional Ethical Committee, and all patients gave informed consent. Care was paid to optimize final results. Residual balloon waists were prospectively assessed, and when detected, aggressively managed with high-pressure dilations with noncompliant balloons. IVUS was performed before and after the procedure (4). Troponin, creatine kinase levels (MB if abnormal), and electrocardiograms were serially obtained. Previous angiograms were reviewed to determine locations of previous stents and sites of ISR. Stent overlap was visually assessed. Views that better displayed ISR lesions were identified and repeated at 9-month follow-up. An automatic angiographic edge-detection system (MEDIS, CMS 4.0, Leiden, the Netherlands) was used. Suboptimal results were defined as a residual diameter stenosis >20%. IVUS were obtained from motorized (0.5 mm/s) pull-backs. Lumen and stent areas were measured at 1-mm intervals. Neointima volume was calculated as stent minus lumen volume (3). Stent expansion was calculated as minimal stent area/mean reference lumen area x 100. Underexpansion was defined as stent expansion <80%. The presence of calcium (1 to 4 quadrants) was analyzed along the stent length. Aspirin and clopidogrel were recommended for 1 year. Major events (death, myocardial infarction, and target vessel revascularization) were verified against source documentation. Target vessel failure included clinical events or angiographic ISR. The Fisher exact test and paired/unpaired Student t tests were used as required. Event-free survival was estimated by Kaplan-Meier analysis. Cox analyses were used to study event predictors. A value of p < 0.05 was considered statistically significant.
Clinical and angiographic characteristics are summarized in Table 1. The results of the second stent were suboptimal in 4 cases despite high deployment pressures. The same occurred after the third (index) procedure: despite higher inflation pressures (20 ± 4 atm, p < 0.05 vs. second stent), residual stenosis was 17 ± 11% (4 patients had suboptimal results). In 6 cases, a residual waist was noticed during last balloon inflation. Before intervention, IVUS studies of adequate quality to assess expansion were obtained in 7 patients. Minimal stent area was 5.9 ± 2.4 mm2 and stent expansion 64.5 ± 19.8%. Neointimal volume was 53.2 ± 41.2 mm3 and stent volume was 147 ± 40 mm3 (33 ± 13% occupied by neointima). Severe calcification (maximal 2.4 ± 0.6 quadrants) was visualized behind all stents. After interventions, data of stent expansion were obtained in 13 patients. Minimal stent area was 5.8 ± 1.7 mm2, stent expansion 67.3 ± 15%, and final stent volume 178 ± 65 mm3. However, in the 6 patients with paired studies (adequate before/after comparisons), minimal stent area improved (5.2 ± 1.8 mm2 vs. 6.6 ± 1.7 mm2, p = 0.03), whereas the changes in stent expansion (60.5 ± 18.4% vs. 75.4 ± 15.4%, p = 0.06) and stent volume (144 ± 45 mm3 vs. 182 ± 59 mm3, p = 0.27) were not statistically significant. Procedural success was obtained in all patients, and no complications occurred (no case presented troponin increases). At last clinical follow-up (median 254 days, interquartile range 77 to 818 days), 2 patients had died. In 1 patient, recurrent ISR developed and the patient underwent a fourth stent implantation, but eventually required surgery (962 days after the index procedure, without target lesion ISR) for left main and multivessel disease, and died after a perioperative myocardial infarction. The second patient died 5 days after a Q-wave target vessel-related myocardial infarction, 53 days after the procedure (probable stent thrombosis, on clopidogrel). A Q-wave myocardial infarction occurred on day 6, caused by a side-branch loss, jailed, but emerging from a patent stent. No additional patient suffered adverse events. At 1 year, the event-free survival was 90% (95% confidence interval: 77% to 99%). Late angiography (median 274 days, interquartile range 196 to 347 days) was obtained in 14 of 16 patients (88% of those eligible, follow-up >9 months). Recurrent ISR was detected in 3 patients: 1 required new DES implantation (the patient who died after surgery); 1 had asymptomatic ISR in a small distal vessel left untreated; the third patient, with moderate, asymptomatic edge-ISR (fractional flow reserve 0.83), was also untreated. IVUS at late follow-up (7 patients) showed a minimal lumen area of 4.2 ± 0.7 mm2, a neointimal volume of 1.2 ± 2.9 mm3 obstructing only 0.5 ± 1.2% of stent volume. On Cox analysis, of all clinical, angiographic, and IVUS variables, only time to ISR (p = 0.01) and IVUS-detected stent underexpansion (p = 0.043) were associated with target vessel failure.
This study shows that DES implantation for recurrences after stenting for ISR is safe and effective. In our series, very high pressures were required to obtain satisfactory angiographic results, although suboptimal results remained in some patients. On IVUS, these patients presented severely underexpanded stents, which remained relatively underexpanded after the third stent despite high-pressure dilations. Heavily calcified vessels seem to explain this phenomenon. Previous studies showed that DES underexpansion predisposes to ISR (4). Our findings emphasize the importance of optimizing final results in patients with ISR because underexpanded stents may not only trigger recurrences but also constitute a challenging substrate for reinterventions. In our series, however, late clinical outcome in patients with complex lesions and recalcitrant ISR was favorable, with a 1-year event-free survival of 90%. We believe that the aggressive dilation strategy coupled with the systematic use of DES played a major role in explaining this benign outcome.
In the ISAR–DESIRE (Intracoronary Stenting or Angioplasty for Restenosis Reduction–Drug-Eluting Stents for In-Stent Restenosis) trial, Kastrati et al. (2) found that the incidence of ISR was significantly reduced after sirolimus-eluting stent and paclitaxel-eluting stent implantation as compared with balloon angioplasty. The RIBS-II (Restenosis Intrastent: Balloon angioplasty versus elective sirolimus-eluting Stenting II) randomized study showed the superiority of DES over balloon angioplasty and confirmed the striking antiproliferative efficacy of DES in this setting (3). No previous study, however, has yet analyzed the results obtained by a third stent implantation in patients with ISR in a coronary segment already housing a double stent layer. Although dilation, with high-pressure noncompliant balloons, has been advocated in patients with underexpanded stents, the results of this strategy remains unsettled. Special care is required to prevent balloon slippage during these aggressive dilations. Alternative techniques to overcome resistant areas of stent underexpansion have not been systematically evaluated. Cutting balloon angioplasty and buddy-wire techniques have been proposed to modify local wall stress, but again, their real value to tackle severe stent underexpansion remains undefined (5). Finally, rotational atherectomy has been proposed in this setting, but the risks associated with this highly aggressive approach seem rarely justified. In patients with ISR and unexpandable stents, the use of additional stenting should not be routinely advocated. However, considering that in this scenario minor neointimal growth could trigger recurrences, DES implantation, coupled with aggressive attempts to expand the underlying stents, seems reasonable. In conclusion, in patients with recurrences after stenting for ISR, DES implantation provides satisfactory long-term clinical, angiographic, and IVUS results.
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1. Alfonso F, Zueco J, Cequier A, et al. A randomized comparison of repeat stenting with balloon angioplasty in patients with restenosis after coronary stenting J Am Coll Cardiol 2003;42:796-805.[Abstract/Free Full Text]2. Kastrati A, Mehilli J, von Beckerath N, et al. Sirolimus-eluting stent or paclitaxel-eluting stent versus balloon angioplasty for prevention of recurrences in patients with coronary in-stent restenosis: a randomized controlled trial JAMA 2005;293:165-171.[Abstract/Free Full Text] 3. Alfonso F, Perez-Vizcayno MJ, Hernandez R, et al. A randomized comparison of sirolimus- eluting stent with balloon angioplasty in patients with in-stent restenosis. Results of the restenosis intrastent: balloon angioplasty versus elective sirolimus-eluting stenting (RIBS II) trial. J Am Coll Cardiol 2006;47:2152-2160.[Abstract/Free Full Text] 4. Fujii K, Mintz GS, Kobayashi Y, et al. Contribution of stent underexpansion to recurrence alter sirolimus-eluting stent implantation for in-stent restenosis Circulation 2004;109:1085-1088.[Abstract/Free Full Text] 5. Balan O, Kobayashi Y, Moses JW. Cutting balloon angioplasty for underexpanded stent deployed through struts of previously implanted stent J Invasive Cardiol 2002;14:697-701.[Medline]
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