NEWS & VIEWS

Progress in Interventional Cardiology

During the last 3 to five 5 years there has been an exponential explosion in the use of intracoronary stents. This device is deployed in at least 50% of all percutaneous coronary interventions and in as many as 70% to 80% of patients in referral centers. Is this prac- tice justified? This issue of News & Views will review the topic of ‘provisional’ stenting.

Provisional Stenting: Will the Balloon Really be Back?

Intracoronary stents reduce the occurrence of is- chemic complications (i.e., abrupt or threatened vessel closure), suboptimal angiographic results, and reduc- tion of target lesion revascularization and angio- graphic restenosis following percutaneous coronary intervention in certain defined clinical and angio- graphic settings.’-5 Stents decrease restenosis in de novo native vessel 1esions’x2 in restenotic lesions, total occlusions, and saphenous vein bypass graft steno- s ~ s . ~ - ~

Despite the numerous benefits and conveniences at- tributed to stent usage, justification of widespread use remains to be established. There are concerns about cost (resource utilization), use in diabetic patients, and placement in small vessels (< 2.5 mm) and long (> 25 mm) or bifurcated lesions. Furthermore, the treatment of in-stent restenoses is unsettled. These issues must be taken into consideration when the use of a stent is being contemplated in a setting where it has not been proven to be superior to balloon angioplasty. Indeed, stents reduce restenosis due to a greater degree of acute gain (greater final lumen diameter) and also by reducing the undesired consequences of remodeling. However, stents are also associated with a greater “late loss” at follow-up due to exuberant intimal hyperpla- sia in contrast to balloon angioplasty alone. This greater late loss may be particularly troublesome in some patients (e.g., diabetics) and with certain vessels or specific lesions.

Notwithstanding the ubiquitous availability of intra- coronary stents, it has been suggested that a more ag- gressive strategy using balloon angioplasty alone to

achieve a larger final lumen diameter (stentlike result) may potentially reduce the incidence of restenosis. It has also been advocated that stents should be used as backup for the treatment of suboptimal results follow- ing percutaneous interventions.

The first question that arises is what should we con- sider as a suboptimal result following balloon angio- plasty in the new stent era. Should a final 20% to 30% residual stenosis or type B and C dissection require provisional stenting? This question has been investi- gated by several groups.“* The late outcome of 1,100 patients enrolled in the Cutting Balloon Randomized Trial recently has been reported. Patients were divided in three groups according to the National Heart Lung and Blood Institute dissection grade classification: none or grade A (68%), grade B or C (27%), and grade D (5%). There was no difference in the incidence of dissections between the cutting balloon and the con- ventional balloon groups. In-hospital clinical events were similar in all three groups (Table 1). No associa- tion between the final degree of a nonflow-limiting dissection and early or late clinical events was found in this trial.6 The late clinical outcome in relationship to final dissection grade after percutaneous coronary in- tervention from an analysis of > 6,000 lesions from the New Approaches of Coronary Interventions (NACI) trial and the Balloon versus Optimal Atherec- tomy trial (BOAT) will be presented at the 7 1 st Scien- tific Sessions of the American Heart Association, November 8-1 1, 1998.7.8

Newer stents are more flexible and trackable and come in a variety of sizes and lengths and may be used in conjunction with 6Fr guiding catheters. Some are visible (radiopaque) and have improved radial strength. In the past few weeks, the Food and Drug Administration has approved two new stent designs (NirTM and RadiusTM, Boston Scientific-MeditoU SciMed Life Systems, Maple Grove, Minnesota. USA) and many more are undergoing clinical eval- uation. Covered and coated stents are being tested in humans. Stents are being evaluated as drug or radiation delivery systems. It would appear that stents are here to stay. However, one must not confuse ease of use with durable clinical benefit. Despite

Vol. 11. No. 6, 1998 Journal of Interventional Cardiology 65 I

NEWS AND VIEWS

Table 1. One-year Events by Dissection Grade in the Cutting Balloon Randomized Clinical Trial

NondA Grade B/C Grade D P ( n = 738, (n = 307) ( n = 55) value

Death 0 0.5 I .3 0 0.4 Myocardial 2.2 3.9 1.8 0.2

CABG surgery Q 1.4 I .o 1.8 0.6 PTCA 51: 11.2 10.1 14.5 0.5 Target lesion 12.3 11.1 16.4 0.4

infarction 51:

revascularization RC

CABG = coronary artery bypass graft: PTCA = percutaneous transluminal coronary angioplasty.

(From Saucedo JF. Talley JD. Ho K. et al. Early and late outcome oi non flow limiting coronary artery dissections in the cutting balloon randomized trial. (abstract) JACC 1998 (Suppl B).

the interest and well-founded arguments on going back to balloon angioplasty and the use of stents as a bailout or backup strategy. one may question whether an interventional cardiologist will sacrifice an aesthet- ically satisfying “luminogram” for an evidence-based practice of stenting.

In a detailed review supporting provisional stenting, Narins et al.’ postulated that at long term follow-up, patients regularly treated with stents should have sim- ilar rates of restenosis as those initially treated with balloon angioplasty and only provisional stenting. That is, as recurrent restenosis following treatment of in-stent restenosis, particularly that species manifested by a diffuse or proliferative pattern. seems to be higher than that following post-FTCA treatment of restenotic lesions, the initial benefit of stenting would be neutral- ized.

In summary, stents are an invaluable tool to treat is- chemic complications during percutaneous coronary interventions. Data are needed to support the use of provisional stenting for the treatment of suboptimal angiographic results following balloon angioplasty. Furthermore, in the new device and stent era, a case can be made to redefine and standardize the meaning of suboptimal angiographic results. Finally, the

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restenosis-sparing benefits of stenting have only been demonstrated in select clinical and angiographic set- tings, and this may not be true for a more universal ap- plication of this therapy. As the recurrence of resteno- sis following treatment of diffuse in-stent lesions seems to be unacceptable, particularly when stents are used to treat diffuse disease in small vessels, and de- spite the plethora of stents available, a more evidence- based practice of stenting should be adopted.

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Jorge Saucedo, M.D. Assistant Professor of Internal Medicine

Director, Cardiac Catheterization Laboratories University of Arkansas for Medical Sciences

J. David Talley, M.D. Professor of Internal Medicine

Director, Division of Cardiology University of Arkansas for Medical Sciences

References

Fishman D. Leon M. Baim D, et al. A randomized comparison of coronary-stent placement and balloon angioplasty in the treatment of coronary artery disease. N Engl J Med 1994; 331:496-501. Serruys P. De Jaegere P, Kiemeneij F. et al. A comparison of balloon-expandable-stent implantation with balloon angio- plasty in patients with coronary artery disease. N Engl J Med 1994.33 I :643446. Simes PA, Golf S, Myreng Y, et al. Stenting in chronic coro- nary occlusion (SICCO). A randomized, controlled trial of adding stent implantation after successful angioplasty. JACC 1996.28 1444-145 I . Erbel R. Haude M, Hopp H et al. Restenosis stent (REST) study; randomized trial comparing stenting and balloon angio- plasty for treatment of restenosis after balloon angioplasty. (abstract) JACC 1996.27:139 A. Savage M. Dough. J. Fischman D et al. Stent placement com- pared with balloon angioplasty for obstructed coronary bypass grafts. N Engl J Med 1997;337:7&747. Saucedo JF, Talley JD. Ho K. et al. Early and late outcome of non flow limiting coronary artery dissections in the cutting bal- loon randomized trial. (abstract) JACC 1998; (Suppl.. B). Saucedo JF, Talley JD. Ho K, et al. Long term clinical impor- tance of coronary artery dissections. (abstract) Circulation 1998 (in press). Saucedo JF, Kennard ED, Talley JD. et al. Long term clinical importance of coronary artery dissections. Insight from the BOAT Trial. (abstract) Circulation 1998 (in press). Narins CR. Holmes DR, Topol W. A call for provisional stent- ing. The balloon is back! Circulation 1998:97:129&1305.

Journal of lnterventional Cardiology Vol. 11, No. 6. 1998