Coronary Stenting for the Treatment of Restenosis After Percutaneous Transluminal Coronary Angioplasty

MICHAEL HAUDE, M.D. and RAIMUND ERBEL, M.D.

From the Cardiology Department, University Essen, Essm, Germany

Introduction

Percutaneous transluminal coronary angioplasty (PTCA) has become a widely accepted standard ther- apy for selected patients with obstructive coronary heart disease. Operator experience and improved cath- eter technology have increased the immediate techni- cal success rate to more than 90%.'12

Nevertheless, symptomatic dissections and abrupt vessel closure during or immediately following the PTCA procedure continue to remain major limitations occumng in 2%- 10% of patients treated3-* and being major determinants of in-hospital morbidity and mor- t a l i t ~ . ~ In approximately 5% of the cases, emergency bypass surgery is necessary when closure is refractory to prolonged balloon inflation, oversized dilatation, or adjunct thrombolytic therapy.'- '

The second limitation of PTCA is the occurrence of restenosis at the dilated site. The incidence of reste- nosis varies between 20% and 57%, depending on the definition used, the kind of coronary lesion treated and the time of angiographic c ~ n t r o l . ' ~ - ' ~ It has been pointed out that acute recoil immediately after balloon deflation and intimal hyperplasia are most likely con- tributing to luminal renarrowing. This process is a time-related phenomenon developing in the first 4 months after PTCA and rarely progressing after 6 r n o n t h ~ . ' ~ , ' ~ , ' ~ - ~ ~ In the case of restenosis, repeat- PTCA can be performed in most patients suitable. Pri- mary success rate, complications, and long-term out- come with respect to the occurrence of restenosis are

Address for reprints: Michael Haude, M.D.. Cardiology Department, University Essen. Hufenlandstr. 55, 45 122 Essen, Germany. Fax: 49-201 -723595 1.

reported to be similar compared to the primary angio- plasty p r~cedure .*~-~ '

Intracoronary Stents

Intracoronary stents were developed to address these major shortcomings of PTCA. Available stents primarily differ in design, material (stainless steel, tan- talum) and in the mode of implantation (self-expanda- ble versus balloon-expandable).30-36 For these stents under clinical use, the rate of successful stent deploy- ment is about 90% or higher with no difference in bail- out or elective ~ t e n t i n g . ~ ' - ~ ~ At present, stenting is the only catheter based technique that provides a scaffold for the instrumented vessel. It prevents vessel collapse and tacks back intimal and medial tears, sealing the thrombogenic subintimal space.

Several studies documented the benefit of bail-out stenting for the treatment of symptomatic dissections or abrupt vessel closure during PTCA."-"

Intracoronary Stents to Prevent Restenosis

Since it was pointed out that elastic recoil, inducing an immediate loss in luminal dimensions and neointi- ma1 hyperplasia are the major contributors to long- term luminal renarrowing, intracoronary stenting might influence both. It has been documented that in- tracoronary stenting prevents almost completely the immediate luminal loss related to elastic recoil. "," -'' Thereby, stenting provides larger immediate relative luminal gain (related to vessel size) as compared to

Vol. 7, No. 4, 1994 Journal of Interventional Cardiology 34 I

HAUDE. ET AL

Table 1.

Mean Mean Mean Patient\ Before After At Acute Late Net

Inter\ ention n PTC A After PTCA Stenting Follow-Up Gain Loss Gain

P1'CA"'

PTCA'I PTCAi2 Palmaz-Schatz" Palinaz-ScharL"' Pslmaz-Schatz" Palmaz-Schatz" Palniaz-Schatz" Palmoz-Schntz" WaII\tent" w i b t or

'6 I 309

50 60

I00 60 ') X 8' 95 SO

1.353

0.90 i 0.35 1.77 i 0.34 0.9X i 0.35 1.77 i- 0.34 1.03 t 0.36 1.78 2 0.36 1 00 & 0.57 2.02 i 0.47 0.08 2 0.43 2.06 2 0.36 1.13 2 0.37 2.03 i 0.36 i.on t 0.24 - 0.73 i 0.48 - 0.66 i 0.32 - I 21 i 0.56 1.88 t 0.43 1.0'9 i 0.26 1.80 i 0.32

3.26 2 0.31 2.98 2 0.26 3.03 2 0.18 2.41 t 0.46

2.85 _t 0.43 2.48 2 0.51 2.45 2 0.35

3.40 2 0.63

1.46 i- 0.59

1.50 i- 0.57 2.39 i- 1.15 2.39 i- 0.58

1.75 i- 0.77 2.18 i 0.92

1.76 1.68 2 1.20 1.59 + 1.79

1.48 1+ 0.54

2.24 2 0.62

0.78 0.3 I 0.47 0.79 0.29 0.50 0.7s 0.28 0.47 2.26 0.78 1.48 2.00 0.59 1.41 I .90 0.79 1 . 1 1 1.41 0.66 0.80 2.67 I .22 1.45 2.19 I .09 1.10 I .27 0.80 0.47 I .36 0.86 0.509

Data iin MLD before and after PTCA or strnting and at follow-up are prezenr as mean 2 standard deviation. Additionally. mean acute gain tMLD after \tenting ininur MLD before .;tenting). mean late loss (MLD after \tenting minus MLD at follow-up), and mean net gain (MLD st follo\\-up minu\ MLD before \tenting) bere calculated.

balloon angioplasty (Table I ) . On the other hand, as a matter of increased vessel wall injury after stenting compared to balloon angioplasty, neointimal prolifera- tion was found to be enhanced. This could be docu- mented by quantitative coronary angiography as a larger relative luminal loss (related to vessel size) at follow-up (Table 1 ). Nevertheless, the overall relative luminal gain (related to vessel sire) was found to be larger after stenting compared to balloon angioplasty (Table I ) . Similar results were found for the subset of patients with long-term restenosis after PTCA" who underwent intracoronary stenting (Fig. 1 ).

Complications Related to Intracoronary Stenting

In-hospital mortality after intracoronary stenting was reported to range between 0% and 4.7% of pa- tients. "'-7' The incidence of acute myocardial infarc- tion was 0% to 8 .99 and emergency coronary artery bypass surgery was performed in up to 5.8% of pa- tients.'"-36 Acute and subacute thrombotic stent occlu- sion several days after stenting were the major limita- tions of this new technique occumng in up to 20% of patients despite aggressive anticoagulation and antiag- gregation On the other hand, bleeding complications were reported in up to 38% of patients, primarily related to the site of arterial puncture in the groin,3LJ-3h.Jh

The REST-Trial

PTCA Versus PTCA with Additional Intracoro- nary Stent Implantation in Patients with Restenosis After an Initially Successful Coronary Balloon An- gioplasty. The primal?; objective of this study is to compare minimal luminal diameter and the extent of late luminal renarrowing 6 months after treatment with repeat-PTCA or repeat-PTCA plus adjunct single Pal- maz-Schatz stent (Johnson & Johnson Interventional Systems, Warren, NJ, USA) implantation in patients with chronic restenosis after PTCA by means of quan- titative coronary angiography. Secondcq objectives include the estimation of the technical success rate and the detection of complications in both treatment arms:

-death -acute myocardial infarction -emergency CABG -thrombotic complications

acute (< 24 hours) subacute (> 24 hours)

-bleeding complications.

Table 2 summarizes inclusion and exclusion criteria of the trial. Since both procedures, PTCA or PTCA plus adjunct stenting, are performed electively in pa- tients with restenosis after PTCA, lesion length was limited to 10 mm so that it could be covered by a single Palmaz-Schatz stent. Since multiple stent implantation per lesion is associated with a significantly higher re-

34' Journal of Interventional Cardiology Vol. 7, No. 4, 1994

CORONARY STENTING FOR THE TREATMENT OF RESTENOSIS AFTER PTCA

n 100

0 0 1 2 3 4

MLD [mrn] before stenting 1.07k0.40 mm mean acute gain: 1.91 mm

L L A after stenting 2.98k0.18 mm mean late loss: 0.76 mm H at 6 months FU 2.2220.65 mm mean net gain: 1.15 mm

Figure 1. Cumulative distribution curves of minimal luminal diameter (MLD) for a subgroup of 53 patients with chronic restenosis after coronary balloon anpioplasty treated with implantation of a single Palmaz- Schatz stent.'5 Results are presented before and after stenting and at 6 months follow-up (FU). Additionally. mean acute gain (minimal luniinal diameter after stenting minus minimal luminal diameter before stenting). mean late loss (minimal luminal diameter after stenting minus minimal luminal diameter at follow-up). and mean net gain (minimal luniinal diameter at follow-up minus minimal luminal diameter before stenting) were calculated.

Table 2. Inclusion and Exclusion Criteria of the REST-Trial

REST-trial

Inclusion Criteria Exclusion Criteria ~

Significant restenosi\ (> 50% diameter reduction or > 50% loss of initial succcss) after a previously successful coronary balloon dilatatioii

Lesion length < 10 rnm Evidence of hemodynamic relevance of this lesion by angina

pectoris, a pathologic stress ECG or thalliuin-?Ol scintigraphy

CABG as an alternative Informed consent

Contraindication for anticoagulation with cournadin Tortuous vessel segment that will not allow balloon catheter i icce~\ Unprotected left main stem stenosis Stenosis location that will he associated with a stem protrusion into the

Unstable angina with respect to the decision of the examining physician Acute myocardial infarction within the last 3 weehs Angiographic evidence of thrombus :it the site of restennsis Bifurcation stenosis Diffuse cot-onary vessel sclerosis distal to the stenosib Patients who are more likely to benefit from CABG Patients not suitable for CABG Women capable of bearing children No informed consent

left main stem or the aorta

CABG = coronary artery bypass grafting; ECG : electrocardiogram.

Journal of lnterventional Cardiology Vol. 7. No. 4. 1994 343

HAUDE. ET A L

stenosis rate compared to single stent implantation or to PTCA," this should be excluded in an elective situ- ation.

Study Design

This is a prospective randomized trial. Patients suit- able for inclusion in the trial are randomized via tele- phone call to the study evaluation center at Essen. Ger- many.

Statistics

Assuming a mean difference in minimal luminal di- ameter (MLD) of 0.5 mm between both groups at 6 months follow-up, a reangiography rate of 8092, a test power of 90% and a 95'70 confidence level, 180 pa- tients have to be enrolled in each treatment arm of the study.

The Stent

In the case of randomization for stenting. single Pal- maz-Schatz stent implantation should be performed using the stent delivery System (SDS, Johnson & Johnson lnterventional Systems). which provides bal- loon diameters of 3.0, 3.5. and 3.0 mm. As an alterna- tive. single Palmaz-Schatz stents can be crimped on

other balloon catheters and will be implanted as de- scribed previously."'

Medication

All patients should be pretreated with aspirin 100 mg/day. Otherwise a loading dose of 500 mg should be administered intravenously (Table 3). During the intervention. high dose heparin is administered in both treatment arms (Table 3) and will be continued in the stent group afterwards by intravenous inlusion to pro- long the afTT to 70-90 seconds. Overlapping oral anticoagulation by phenprocoumon should be initiated immediately, or on the day after stent placement. When stable oral anticoagulation is maintained with an INR > 3 . heparin can be terminated. Phenprocoumon should be administered for 3 months. Additionally. patients with stent implantation will receive aspirin 300 mg/day indefinitely in contrast to patients with PTCA who will receive 100 mg/day (Table 3).

If available, monitoring of prothrombin and pro- thrombin fragment 1 + 2 should be included since it has been shown that monitoring of these parameters resulted in a significantly reduced rate of hubacute thrombotic complications.48

Quantitative Coronary Angiography

Each set of films per patient (acute and 6 months follow-up) is sent to the quantitative coronary angiog-

Table 3. Recommendation5 tor Anticoagulation and Antiaggregation Therapy in the REST-Trial

PTCA-Croup Stent-Group

Medication Before Intervention Aspirin 100 mg/day or in the cabe of no pretreatment Aspirin 500 rng IV a3 a loading dow

During Intervention 15,OOO IU heparin ah a bolub I\'. 1A 1.500 1Uhour heparin IV 3,OOC 1U heparin IC after interbention 0.2 mg NTG IC before each \et of angiograms

After Intervention hepann 1.500 IChour tor 24 hour, aspinn 100 nig/day indetinitelb

Medication Before Intervention Aspirin 100 @day or in the w e of no pretreatment Aspirin 500 rng IV

1S.ooO IU hepann as a bolus IV. IA 1.500 IUhour heparin IV 3.OOO IU heparin IC af-ter intervention 0.2 mg NTG IC before each set of angiograms

After Intervention continuous intravenouh heparin infusion to prolong aPT7' to iiiore than 70s until overlapping oral anticoagulation with phenprocoumon induces an INR ';. 3 then IV hepann withdrawal and continuation of phenprocoumon administation for 3 month> a\pinn 300 mg/day

a loading dose Dunng Intervention

3 4 4 Journal of lnterventional Cardiology Vol . 7. N o 4, lY94

CORONARY STENTING FOR THE TREATMENT OF RESTENOSIS AFTER PTCA

Table 4. Participating Centers of the REST-Trial Who Have Enrolled Patients

REST-Trial

University Essen University Mainz University Cologne Medical School Hannover Thoraxcenter Rotterdam University Berlin University Vienna University Kiel University Erlangen

Prof. Dr. Erbel, Dr. Haude Prof. Dr. Meyer, PD Dr. Rupprecht Prof. Dr. Hoepp, Dr. Franzen Prof. Dr. Heublein, Dr. Nolte Prof. Dr. Sermys, Dr. deJaegere Prof. Dr. Rutsch Prof. Dr. Probst Prof. Dr. Simon, PD Dr. Henmann Prof. Dr. Kunkel

raphy (QCA) core laboratory at the University of Essen, Germany. Quantitative evaluation will be per- formed by the Cardiovascular Measurement System (CMS; MEDIS, Leiden, The Netherlands) using a standard protocol and the guiding catheter for calibra- ti0n.4~ Minimal luminal diameters in absolute and rela- tive terms before and after PTCA, after stenting and at 6 months follow-up are the target parameters.

Participating Centers and Actual Enrollment Status

A total of nine centers have gained approval of the local ethical committee and started patient enrollment since August 1, 1991. A list of these centers is pre- sented in Table 4. As of February 1, 1994 a total of 130 patients were randomized.

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