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(Circulation. 1998;97:1298-1305.)
© 1998 American Heart Association, Inc.

Current Perspectives

A Call for Provisional Stenting

The Balloon Is Back!

Craig R. Narins, MD; David R. Holmes, Jr, MD; ; Eric J. Topol, MD

From the Department of Cardiology and Joseph J. Jacobs Center for Vascular Biology, The Cleveland Clinic Foundation, Cleveland, Ohio; and the Division of Cardiovascular Diseases, Mayo Clinic and Mayo Foundation, Rochester, Minn.

Correspondence to Eric J. Topol, MD, Department of Cardiology, F25, The Cleveland Clinic Foundation, 9500 Euclid Ave, Cleveland, OH 44195. E-mail topole{at}cesmtp.ccf.org

Key Words: stents • balloon • revascularization

	Introduction

Top Introduction Balloon Angioplasty: Historical... Debulking and Ablative... Coronary Stents The "Aggressive" Approach to... Conclusions References

 
During the past 20 years, the equipment used to perform percutaneous coronary revascularization has undergone a dramatic transformation from simple balloon dilatation catheters to sophisticated mechanical devices and endoprostheses. The impetus for this evolution in technology was initially a byproduct of suboptimal immediate and long-term results obtained with standard balloon angioplasty. New techniques, including directional and rotational atherectomy, have resulted in improved procedural success rates, especially for more complex lesion subtypes, although their ability to curtail restenosis remains controversial.^{1 2} Intracoronary stents have had a dramatic impact on reduction of the incidence of acute complications after failed balloon angioplasty and represent the only currently available strategy shown to limit both clinical and angiographic restenosis.^{3 4 5 6 7 8 9 10 11 12} Based on these advantages, stent implantation is used in approximately half of all percutaneous interventions in the United States. However, despite their proven benefits, coronary stents continue to be accompanied by several theoretical and practical limitations: they are costly, typically associated with a more marked degree of neointimal formation than balloon angioplasty, and difficult to use with some lesion subsets such as bifurcation stenoses, and they have engendered the new and difficult-to-treat entity of in-stent restenosis.

Although the major focus in the field of interventional cardiology over the past decade has been on the development of new devices and adjunctive pharmacological therapies, the short- and long-term success rates after standard balloon angioplasty have improved significantly. Part of the improvement is likely a manifestation of enhanced operator experience and better equipment, but the results of balloon angioplasty have also benefited greatly from the availability of coronary stents for both "bailout" (for actual or threatened abrupt closure) or "backup" (for suboptimal balloon results) indications, potentially allowing a strategy of more aggressive balloon dilatation than could be safely performed in the pre-stent era. This report details the forces that resulted in the shift from reliance on balloon angioplasty as the primary mode of therapy for the majority of percutaneous interventions and, with the use of data from several recent clinical trials, will provide the rationale for a potential return to the use of balloon angioplasty (with provisional stent placement) as the predominant means of coronary revascularization.

	Balloon Angioplasty: Historical Experience

Top Introduction Balloon Angioplasty: Historical... Debulking and Ablative... Coronary Stents The "Aggressive" Approach to... Conclusions References

 
Balloon dilatation, by virtue of barotrauma to the vessel wall, has long been recognized as a technique with a certain degree of unpredictability. Necropsy studies of coronary segments in the hours to days after successful balloon angioplasty in patients who died from cardiac and noncardiac causes demonstrate the near-universal presence of intimal tears at the site of dilatation with variable degrees of associated medial penetration, ranging from minimal intimal disruption to extensive dissection during angioplasty with concomitant vessel closure.¹³ Although major dissection and abrupt vessel closure have been associated with certain angiographic features (including proximal vessel tortuosity, lesion eccentricity, length, and angulation), these potentially catastrophic events tend to be difficult to predict for any individual patient.^{14 15} Abrupt closure resulting from balloon angioplasty occurred in 4.5% of the 1155 patients enrolled in the initial NHLBI registry between 1979 and 1981.¹⁶ Among those with periprocedural vessel occlusion, 41% had a myocardial infarction and 72% required bypass surgery, and the overall mortality rate was 4.9%. Despite improved experience with the procedure, the incidence of abrupt closure after balloon dilatation in the late 1980s and early 1990s remained in the range of 4% to 8%, with >20% of these patients requiring an emergency bypass operation despite the use of longer inflations and perfusion devices.^{17 18}

Apart from acute complications, balloon angioplasty as performed in the 1980s was associated with the frequent occurrence of angiographic and clinical restenosis. The binary restenosis rates reported for the placebo arms in 28 large (study population of >100) prospective trials of adjunctive pharmacological therapy after balloon angioplasty published between 1985 and 1993 varied from 19% to 63%, with the majority falling in the 30% to 50% range.¹⁹ The need for target lesion revascularization during 6-month follow-up generally ranged from 20% to 30%. Despite evidence indicating that restenosis rates are inversely proportional to postprocedural luminal diameter,²⁰ the unpredictable response of the lesion site to balloon dilatation coupled with the significant morbidity and mortality rates associated with abrupt vessel closure limits the aggressiveness of balloon angioplasty.^{21 22}

	Debulking and Ablative Techniques

Top Introduction Balloon Angioplasty: Historical... Debulking and Ablative... Coronary Stents The "Aggressive" Approach to... Conclusions References

 
As a direct result of the suboptimal procedural success, acute complication, and restenosis rates after stand-alone balloon angioplasty, a variety of technologically advanced devices have been developed. The clinical efficacy of two ablative devices, excimer laser coronary angioplasty and rotational atherectomy, was examined relative to that of balloon angioplasty in the randomized ERBAC study of 620 patients with high-risk (American College of Cardiology/American Heart Association type B or C) angiographic lesion morphology.² Despite significantly improved procedural success in patients randomized to rotational atherectomy relative to the other treatment strategies, neither of the new devices resulted in a reduction in the 6-month angiographic restenosis rate. Repeat target lesion revascularization actually was more frequent in patients who underwent laser angioplasty and rotational atherectomy than in those treated with balloon angioplasty (46% versus 46% versus 35%; respectively; P=.04).

The efficacy of directional coronary atherectomy (DCA) relative to balloon angioplasty was investigated in the large multicenter Coronary Angioplasty versus Excisional Atherectomy Trial (CAVEAT-1).¹ Among 1012 patients with de novo coronary stenoses that were suitable for either form of revascularization, atherectomy was associated with an improved procedural success rate relative to balloon angioplasty (89% versus 80%). The improved procedural success in the atherectomy-treated patients, however, came at the cost of a significant increase in early procedural complications (predominantly abrupt vessel closure and non–Q-wave myocardial infarction). Despite a trend toward reduced angiographic restenosis in the atherectomy group at 6 months (50% versus 57%; P=.06), 1-year clinical follow-up revealed a statistically significant excess mortality rate in the atherectomy group (2.2% versus 0.6%; P=.035).²³

The Balloon versus Optimal Atherectomy Trial (BOAT), of which the preliminary results were recently reported, was designed to study the efficacy of a more aggressive ("optimal") approach to DCA.²⁴ In this large multicenter trial, atherectomy resulted in significantly reduced immediate postprocedural residual stenosis (14% versus 28%). The study confirmed the CAVEAT finding of an increased incidence of non–Q-wave infarction in patients treated with DCA. In contrast to CAVEAT, angiographic restenosis was decreased in atherectomized patients (32% versus 40%; P=.017). Despite the statistically significant reduction in angiographic restenosis, there was no reduction in the need for target vessel revascularization at 1 year (17.1% versus 19.7%; P=.33). One-year mortality rates were low and did not differ significantly among patients treated with atherectomy or balloon angioplasty (0.6% versus 1.6%, respectively).

	Coronary Stents

Top Introduction Balloon Angioplasty: Historical... Debulking and Ablative... Coronary Stents The "Aggressive" Approach to... Conclusions References

 
Stents as "Bailout" Devices
Coronary stents, by virtue of their ability to eliminate vessel recoil and serve as mechanical scaffolds to "tack up" significant dissection flaps, were first approved for use in the United States as a means to treat threatened or actual abrupt vessel closure after failed balloon angioplasty. Although the usefulness of emergency stent implantation over that of repeat balloon inflations has never been documented in a randomized trial, multiple observational reports have consistently illustrated the advantages of coronary stents as "bailout" devices (Table 1).^{3 4 5 6 7 8 9 10} In the largest case series, George et al⁴ reported successful deployment of the Gianturco-Roubin stent in 95.4% of 494 patients with abrupt or threatened abrupt closure during angioplasty. Only 4.3% of patients in this series required emergency bypass surgery, a clear improvement compared with rates typically of >20% in the prestent era. Lincoff et al,⁵ using a matched case-control approach, compared the results of Gianturco-Roubin stent implantation in 61 patients with threatened or actual abrupt closure with those for patients after conventional (balloon-based) therapy in 61 historical control subjects treated before the availability of stents. Stent placement was associated with less residual stenosis (26% versus 49%; P<.001), increased restoration of TIMI grade 3 flow (97% versus 72%; P<.001), and reduced need for emergency bypass surgery (4.9% versus 18%; P=.02), although the rates of subsequent Q-wave myocardial infarction or death did not differ among the treatment groups. In a more recent study of 2242 consecutive patients who underwent percutaneous coronary revascularization at a single center between 1991 and 1994, patients treated after the availability of bailout stenting, despite an increased prevalence of high-risk baseline characteristics (eg, unstable angina, diabetes), had a reduced incidence of major in-hospital complications (2.0% versus 4.1%; P<.01) and emergency bypass surgery (1.1% versus 2.9%; P<.01) than those treated in the prestent era.²⁵ In summary, although no prospective randomized trial has confirmed an improved late clinical outcome as a result of unplanned stent implantation, bailout stenting is associated with high rates of angiographic success and infrequent need for emergency surgery. The practice of stent implantation in the setting of acute or threatened abrupt vessel closure has become established to the point where most interventional cardiologists would deem a randomized trial in which stenting was compared with more conservative treatment approaches to be unethical.

View this table: [in this window] [in a new window]   Table 1. Results of Bailout Coronary Stent Implantation

Stents as Antirestenosis Devices
Although stents have been associated with a dramatic decline in acute complication rates after angioplasty, the ability of stents to limit restenosis, as demonstrated in the landmark Stent Restenosis Study (STRESS) and Belgium Netherlands Stent Study Group (BENESTENT) trials has served as the true catalyst for the pervasive increase in stent use over the past 3 to 4 years.^{11 12} In both STRESS and BENESTENT, patients with favorable lesion characteristics (eg, discrete, de novo lesions in large vessels) were randomized to undergo elective Palmaz-Schatz stent implantation or standard balloon angioplasty (Table 2). In both trials, stent placement was associated with significantly larger immediate improvements in minimal luminal diameter (MLD) at the lesion site. However, much of the initial benefit in terms of luminal gain resulting from stent implantation was lost during the follow-up period, as reflected by significantly greater "late loss" (immediate postprocedural MLD minus the late follow-up MLD) in the stent groups. As a result, the improvement in luminal diameter afforded by stent placement over balloon angioplasty (as reflected by the "net gain" in MLD between the preprocedural and late follow-up angiograms) was very small in absolute terms, equaling an average of only 0.18 mm in STRESS and 0.10 mm in BENESTENT. Despite these small absolute differences in vessel size at follow-up, stent placement was associated with reduced binary angiographic restenosis rates in both trials; however, a statistically significant reduction in the need for target lesion revascularization, the ultimate clinical marker of restenosis, was achieved in BENESTENT but not in STRESS. There were no differences in the incidence of death or myocardial infarction between the stent and balloon angioplasty groups, although these events occurred infrequently in these trials.

View this table: [in this window] [in a new window]   Table 2. Results of the STRESS and BENESTENT Trials

Since the publication of the results of STRESS and BENESTENT, the strategy of ensuring optimal stent deployment via high-pressure balloon inflation within the stent has reduced the incidence of subacute stent thrombosis, permitting the use of far less aggressive antithrombotic regimens after the procedure.²⁶ Several randomized trials have demonstrated the efficacy and safety of antiplatelet therapy alone (with aspirin and ticlopidine) relative to regimens including anticoagulation therapy (with warfarin) after stent placement.^{27 28 29} The reduction in the risk of subacute stent thrombosis afforded by optimal stent expansion coupled with the reduced incidence of vascular and bleeding complications that have accompanied the discontinued use of warfarin after stent implantation has been responsible for the dramatic increase in stent use.

Whether this strategy of optimal stent deployment has the potential to further improve on restenosis rates after stent placement remains uncertain. Recently presented data from the STRESS-III trial, in which 250 patients with focal de novo stenoses in native coronary arteries underwent Palmaz-Schatz stent placement with the use of high-pressure inflations in conjunction with aspirin and ticlopidine therapy, suggest that optimal stent expansion techniques may offer no added benefit in terms of subsequent restenosis.³⁰ Compared with patients enrolled in the STRESS-I trial, who underwent stent placement accompanied by the aggressive antithrombotic regimen used at the time the trial was conducted, patients in STRESS-III experienced a significant reduction in bleeding and vascular complications (2.1% versus 7.3%) and a nonsignificant trend toward reduced subacute closure (3.4% versus 1.3%). The use of high-pressure inflations after stent deployment in STRESS-III was associated with a slight but statistically significant improvement in acute luminal gain compared with the stent group in STRESS-I (1.86 versus 1.73 mm), but this gain was offset by an equivalent increase in late loss (0.92 versus 0.76 mm) on 6-month follow-up angiography. The late loss index (late loss divided by acute gain), which in stented patients represents an angiographic measure of the severity of neointimal hyperplasia, was significantly greater in the group treated with high pressure after dilatation. As a result, binary restenosis rates were virtually identical among patients undergoing stent implantation in STRESS-III and STRESS-I (31.4% versus 31.6%). These finding suggest that although newer stent implantation techniques reduce acute periprocedural complications and decrease the length of hospital stay, they do not appear to provide any salutary benefit in terms of further reducing the incidence of restenosis.

Problems With Stenting
The reduced potential for bleeding complications, coupled with the superior immediate angiographic appearance afforded by stents and the reduced incidence of restenosis observed in STRESS and BENESTENT, has engendered overriding enthusiasm for stent implantation for wide-ranging indications that initially outstripped the supporting scientific evidence.³¹ The widespread zeal for stent use within the interventional cardiology community is highlighted by a recent report from the Mayo Clinic in which 59.4% of all procedures involving stent implantation performed at that institution between July and December 1995 involved the use of an unapproved device or an unapproved indication for an approved device.³² Only in recent months have chronic total occlusions,³³ lesions in saphenous vein grafts,³⁴ and restenotic lesions³⁵ been validated for stent implantation. It is important to consider that the particular benefit of stent implantation in lesions with complex characteristics that, by design, were excluded from STRESS and BENESTENT (eg, long lesions requiring multiple stents, lesions involving vessel ostia or bifurcations, lesions in vessels <3 mm in diameter) has not been confirmed in a randomized fashion.

The primary impetus for the dramatic increase in stent use is based on the STRESS and BENESTENT data, but several intriguing reports have recently highlighted the discrepancies between patients undergoing stent insertion in the "real world" and the highly selected group studied in these randomized trials (Table 3).^{36 37 38 39} For example, in a series of 700 consecutive patients with 745 lesions treated with coronary stents, Sawada et al³⁶ found that only 20% of the lesions would have been eligible for inclusion in STRESS and BENESTENT. Although the 6-month restenosis rate in this series was 11% for STRESS/BENESTENT equivalent lesions, restenosis occurred in >30% of lesions that would have been excluded from these randomized trials.³⁶ In a separate series, among 522 consecutive patients in a multicenter registry who underwent stent implantation, only 7% would have qualified for STRESS and BENESTENT, and the incidence of adverse clinical events (death, myocardial infarction, or target lesion revascularization) at 1 year was twofold higher among STRESS- and BENESTENT-ineligible patients versus eligible patients³⁹ (Table 3). These provocative observational reports suggest that when applied to a less-select group of patients than those studied in the randomized trials, the relative advantages of stent implantation may be significantly attenuated.

View this table: [in this window] [in a new window]   Table 3. Results of Stenting in the "Real World"

Although difficult to evaluate scientifically, another principal reason stent implantation has become so commonplace most likely results from the predictable and reliable acute outcomes provided by these devices. Particularly for the less skilled or experienced operator, who may be less likely to achieve an excellent result with balloon angioplasty alone, stent placement can increase the likelihood of obtaining a more acceptable procedural outcome. As the new generation of stents, which from a technical standpoint will make stents easier to deploy throughout the coronary tree, become available for use in the United States, the proportion of coronary interventions involving stent implantation will probably continue to rise.

Even among patients with currently approved indications for stent use, several important words of caution are in order. First, and perhaps most important, stent implantation has engendered a new and clinically frustrating entity: in-stent restenosis. Although stent implantation results in significantly larger immediate luminal diameters than balloon angioplasty, stents also provoke an exaggerated proliferative response within the vascular wall, resulting in excessive neointimal formation relative to balloon-induced injury. This process is reflected by the significantly greater "late loss" in MLD seen in STRESS and BENESTENT, which substantially mitigated the initial angiographic advantages of stenting.

Although stent implantation is associated with a reduced incidence of restenosis relative to balloon angioplasty in certain lesion types, when neointimal hyperplasia occurs to a degree sufficient to cause diffuse in-stent restenosis, the efficacy of repeat angioplasty appears poor. Preliminary observational reports have described rates of recurrent restenosis after balloon angioplasty for the treatment of in-stent restenosis ranging from 30% to 57% (Table 4).^{40 41 42 43 44} In a subgroup of patients with diffuse in-stent restenosis studied by Yokoi et al⁴⁰ who were treated with repeat balloon dilatation within the stent, the incidence of recurrent restenosis was 85%. Although all studies to date have been small and retrospective and have lacked an adequate rate of angiographic follow-up, the prognosis after in-stent restenosis, especially when diffuse in nature, appears worse than that for restenotic lesions in nonstented segments. Thus, although primary stenting is associated with a reduction in the need for repeat target lesion revascularization compared with a strategy of primary balloon angioplasty in selected patient groups, given the high rate of recurrence after the treatment of in-stent restenosis, the initial benefits of stent implantation may be less dramatic (Figure).

View this table: [in this window] [in a new window]   Table 4. Recurrent Restenosis After Balloon Angioplasty for Treatment of In-Stent Restenosis

View larger version (15K): [in this window] [in a new window]   Figure 1. Theoretical outcomes of strategies of primary versus provisional stent implantation in 100 patients with long (>15 mm) lesions. This model is designed to illustrate the potential use of provisional as opposed to planned stenting in complex lesion types. The data used are speculative but are based on studies examining outcomes after angioplasty and stenting for long lesions.39 58 59 60

Routine coronary stent implantation also is more expensive than balloon angioplasty. Despite lower follow-up medical costs resulting from the need for fewer repeat revascularization procedures and subsequent hospital admissions, the STRESS investigators determined that the total medical costs at 1 year were $800 per patient higher in patients treated with elective stenting as opposed to those treated with conventional angioplasty.⁴⁵ Furthermore, although intermediate-term follow-up data now exist to support the continued safety and efficacy of stents up to 3 to 6 years after implantation of single stents for focal lesions,^{46 47} the longer-term safety profile of these permanent endovascular prostheses, especially in the setting of diffuse disease, remains to be determined.

	The "Aggressive" Approach to Angioplasty

Top Introduction Balloon Angioplasty: Historical... Debulking and Ablative... Coronary Stents The "Aggressive" Approach to... Conclusions References

 
Coronary stenting has occupied center stage among interventional technologies for most of this decade, but an interesting phenomenon has occurred—the efficacy of stand-alone balloon angioplasty has improved. In the prestent era, despite the fundamental tenet in interventional cardiology that larger immediate postprocedural luminal diameters are associated with lower rates of restenosis, the fear of major dissection and its attendant sequelae served to limit the aggressiveness with which balloon dilatation could be safely performed.^{21 22} With the knowledge that stents are "on the shelf," however, the interventionalist now has access to a "safety net" that in many instances can allow more aggressive attempts to optimize luminal gain via balloon dilatation. Furthermore, the availability and efficacy of platelet glycoprotein IIb/IIIa receptor inhibitors in reducing acute thrombotic complications of angioplasty have significantly improved the safety of balloon angioplasty.^{48 49}

Powerful evidence for the improved efficacy of balloon angioplasty is apparent on examination of the clinical outcomes of angioplasty in the balloon (control) arms of three recently completed major clinical trials: BOAT, BENESTENT-II, and Evaluation in PTCA to Improve Long-term Outcome with Abciximab GP IIb/IIIa Blockade (EPILOG) (Table 5).^{24 49 50} In each of these trials, either a device (heparin-coated Palmaz-Schatz stents in BENESTENT-II and directional atherectomy in BOAT) or a pharmacological agent (abciximab in EPILOG) was examined in the experimental arm, whereas patients in the control arms were treated aggressively with balloon angioplasty, with the goal being the smallest possible residual stenosis.

View this table: [in this window] [in a new window]   Table 5. Target Lesion Revascularization Rates With "Aggressive" Balloon Angioplasty in Three Recent Trials

Stent placement in the angioplasty arms of each trial was discouraged by protocol design, and the investigators were careful to follow this recommendation accordingly. In each of the three trials, there was a low and remarkably consistent 14% rate of crossover to stenting in the patients randomized to receive balloon angioplasty. Despite the infrequent use of coronary stents, the overall rate of target vessel revascularization (the primary indicator of clinical restenosis) during follow-up among the large number of patients randomized to balloon dilatation in these three separate trials was 17.5%. This represents a clear improvement relative to rates consistently >20% in the prestent era. The rate of repeat percutaneous revascularization in patients treated with balloon angioplasty in the CAVEAT-I trial, for example, was 30.4%.

These results provide exciting preliminary evidence that a strategy of more aggressive balloon dilatation with the limited use of provisional stenting for complicated or suboptimal balloon results may be highly effective. Based on the finding that >80% of patients in the balloon angioplasty arms of these trials remained free from clinical restenosis, the critical question to be addressed appears not to be whether a strategy of universal stent placement is superior to one of universal balloon angioplasty but rather how can these two approaches best be used together to optimize clinical results? In other words, how do we prospectively identify which of the minority of patients treated with angioplasty will benefit from adjunctive stent placement? Thus far, apart from the presence of a large luminal area immediately after the procedure, both angiography and intravascular ultrasound have failed to identify strong morphological predictors of restenosis after balloon angioplasty or stent implantation.^{51 52}

Patients randomized to receive primary stent placement in BENESTENT-II did maintain a statistically significant reduction in the need for repeat revascularization over balloon-treated patients; however, the difference was relatively small (5.5%) in absolute terms, meaning that stent implantation would have to be undertaken in 100 patients to benefit 5 or 6. It is not known what percentage of patients treated with an approach of provisional stenting would have to undergo stent placement to achieve results comparable to the current strategy of routine primary stent placement in suitable vessels. Absent any specific data in this regard, the need for backup stenting to obtain comparable results is likely to be in the range of 20% to 40% (in any event, higher than the 14% rate of the balloon arms of recent randomized trials).

Preliminary subgroup data from the BENESTENT-I trial provide strong support for the efficacy of stand-alone balloon angioplasty when "stent-like" results are obtained. Among the 90 patients in that trial who were randomized to receive balloon angioplasty and left with a 30% residual stenosis (as determined by quantitative angiography), the minimal luminal diameter at follow-up (1.84±0.52 mm), binary restenosis rate (16%), and 1-year event-free survival rate (77%) were nearly identical to those observed in patients who were randomized to receive stent placement.⁵³

The safety and procedural results of balloon angioplasty may be further enhanced by the selective use of intravascular ultrasound to accurately measure vessel caliber (typically underestimated by angiography) and guide the safe use of balloons that would traditionally be considered oversized. In the Clinical Outcomes with Ultrasound Trial (CLOUT), intravascular ultrasound performed in 102 patients immediately after angioplasty with balloons sized on the basis of angiographic estimation of vessel diameter indicated that even larger balloons (average balloon-to-artery ratio of 1.3:1) could be used in 73%. Subsequent dilatation with these traditionally oversized balloons resulted in a significant increase in MLD (from 1.95±0.49 to 2.21±0.47 mm) without a corresponding increase in the incidence of angiographic dissection.⁵⁴ Measurement of coronary flow reserve using the Doppler guidewire represents another potential end point on which to base the decision of whether to provisionally stent a lesion after balloon angioplasty has been completed.⁵⁵ In a preliminary clinical trial, patients in whom normalization of coronary flow reserve did not occur immediately after angiographically successful balloon angioplasty demonstrated an increased risk for recurrent events and may represent a subgroup who would benefit from provisional stent placement.⁵⁶

Given the promising data from BENESTENT, BOAT, and EPILOG, randomized controlled trials comparing the strategy of universal stent implantation with the seemingly more pragmatic approach of initial "aggressive" angioplasty followed by provisional stenting for suboptimal balloon results are clearly indicated. Objective parameters would need to be set to govern when unplanned stent placement would be permitted—for example, actual or threatened abrupt closure, dissection >10 mm in length, or residual narrowing >30% by on-line quantitative angiography after maximal balloon dilatation. Although it might be expected that stenting in a bailout situation would be associated with more sequelae than primary stent placement, these events would be tabulated and included in such a trial. Importantly, long-term follow-up (12 months) would be necessary so the sequelae of restenosis, especially those of in-stent restenosis, could be accounted for. Subgroup analysis may provide insights into which clinical or angiographic features might show a particular benefit (or lack thereof) from primary stent use. An economic cost-benefit analysis of the competing strategies also will provide important information.

Results of the Optimal Coronary Balloon Angioplasty versus Stent (OCBAS) study, a small initial randomized trial addressing the use of provisional stenting, were recently presented.⁵⁷ In this study, 116 patients with good immediate results after initial balloon angioplasty were randomized to a strategy of either elective stent placement or optimal angioplasty with provisional stenting only for lesions that demonstrated excessive early loss (>0.30 mm) within 30 minutes of balloon dilatation. Only 13.5% of patients in the angioplasty arm ultimately required stent implantation, and angiographic and clinical follow-up demonstrated no significant differences between the two strategies in terms of binary restenosis, target vessel revascularization, and freedom from major clinical events. These preliminary findings provide a basis for larger confirmatory trials.

	Conclusions

Top Introduction Balloon Angioplasty: Historical... Debulking and Ablative... Coronary Stents The "Aggressive" Approach to... Conclusions References

 
Based on currently available data, coronary stent implantation should best be viewed not as an alternative but rather as an adjunct to balloon angioplasty in many clinical situations. Although a strategy of routine stent placement provided modest angiographic and clinical advantages over one of routine balloon angioplasty in the STRESS and BENESTENT trials, these studies by design excluded the vast majority of lesion morphologies encountered in clinical practice (Table 3) and did not allow an approach of provisional stenting for suboptimal balloon results. Further investigation is necessary to better define the optimal indications for primary and secondary stent use. However, until (1) the problem of in-stent restenosis can be effectively addressed, (2) the efficacy of stenting in lesions with more complex lesion morphologies can be proved, (3) the economic costs of stenting can be reduced, (4) long-term data exist to confirm the lack of late sequelae associated with permanent implantation of metallic devices in the coronary arterial wall, and, most importantly, (5) the strategy of planned stent placement can be documented to be superior to one of aggressive balloon angioplasty with provisional stenting, it will remain difficult to justify the primary use of stents in the majority of percutaneous coronary interventions.

	References

Top Introduction Balloon Angioplasty: Historical... Debulking and Ablative... Coronary Stents The "Aggressive" Approach to... Conclusions References

 

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