- Email: [email protected]
Usefulness of the Wiktor Stent for treatment of threatened or acute closure complicating coronary angioplasty
Usefulness of the Wiktor Sent for Treatment of Threatened or Acute Closure Complicating Coronary Angioplasty Matty Vrolix, MD, and Jan Piessens, MD, for the European Wiktor Stent Study Group*
The purpose of this study was to determine the results of the first Wiktor stent implantations in bailout conditions. From December 1999 to July 1991, in a total of 10 centers, 69 patients presenting with threatened or total closure after balloon angmplasty each received the Wiktor stemt in 1 coronary artery. In these 69 coronary arteries, a total of 72 stent deliveries were attempted and 69 were successful (delivery sue cess rate 95%). Delivery failure was treated conservatively in 2 patients and surgically in 1 patient. Emergency surgery was also performed in 2 patients, who after successful stent delivery showed progressive distal extension of the dissection. In addition, 5 patients underwent elective surgery to avoid the possibllity of stent thrombosis because the myocardial area at risk was considered too large. Postprocedural blood transfusion was pehrmed in 6% of the patient& whereas stent thrombosis occurred in 10 of 59 patients (17%), resulting in 2 deaths. Finally, 65% of the patients had a successful stent implantation without major periprccedural complications. At &month followup, only 9% of the patients experienced recurrent angina, whereas a ~59% arterial diameter narrowing was observed in 27% of the patients. Thus, the radlopaque Wlktor stent can be accurately and conveniently implanted in dissected coronary arterial segments. However, as for similar bailout devices, the number of thrombotic and bleeding events remains high. (Am J Cardiol1994;73:737-741)
From the European Wiktor Stent Study Centers (see Appendix). Manuscript received July 6, 1993; revised manuscript received September 17, 1993, and accepted September 21. Address for reprints: Jan Piessens, MD, Department of Cardiology, University Hospital Gasthuisberg, Herestraat 49, B 3000 Leuven, Belgium. *See Appendix
for list of participants
in the Wiktor
Stent Study.
I
ntracoronary stents have recently been developed to reduce the problems of acute reocclusion complicating coronary angioplasty. For this purpose, 2 types of stents, either self-expandable or balloon-expandable, have been tested in several clinical trials.lA A large body of experimental and clinical evidence indicates the efficacy of these devices but, at the present time, the technique remains limited by poor fluoroscopic visibility and by the thrombogenic potential of the devices. Recently, a new radiopaque tantalum stent, the WiktorB stent, became available in Europe for clinical use.5-8 This study presents the first multicenter experience using this stent to manage acute or threatened vessel closure. METHODS Balloouexpsndable intracoronary stent: The balloon-expandable stent used in the present study (W&or, Medtronic, Inc., Minneapolis, Minnesota) is constructed of a single tantalum wire (diameter 0.127 mm), which is formed into a sinusoidal wave and wrapped into a helical coil structure. The prosthesis, 15 f 2 mm long, is premounted on a polyethylene balloon of a standard angioplasty catheter (Figure 1). The device was used under the Food and Drug Administration investigational device exemption status as part of a multicenter study, and the study was approved by the ethical committee of each participating institution. Patients: From December 1990 through July 1991, intracoronary stenting was attempted in 69 consecutive patients (11 women and 58 men), all presenting with acute or threatened vessel closure accompanied by anginal pain or ischemic electrocardiographic changes, or both, during or after balloon angioplasty. The study protocol allowed stenting in all 3 major coronary arteries; venous grafts as well as chronic occlusions were excluded. All patients gave written informed consent for stent implantation and 6-month control angiography. Procedure: Stent implantations were performed as previously described.8 Because implantations were performed under bailout conditions, premeditation consisted of only 500 mg of oral or intravenous aspirin and an intravenous bolus of 10,000 IU of heparin in addition to the routine dose used during coronary angioplasty in each individual center. An infusion of dextran 40 (1,000 ml) at a rate of 100 ml/hour was begun just before stent implantation, while the routine heparin infusion at 1,000 IU/hour was continued. Implantation of 1 single stent was recommended for long dissections, but the exact location of the stent and the administration of thrombolytic therapy were left to the discretion of the operator. The intraarterial sheath was removed 4 to 8 hours after im-
WIKTOR STENTAS BAILOUT DEVICE 737
plantation at a time when, after interruption of the heparin infusion, the activated partial thromboplastin time was ~80 seconds; the heparin infusion was restarted 4 hours later and monitored in order to maintain the partial thromboplastin time between 80 and 120 seconds. The heparin infusion was withheld as soon as warfarin treatment had resulted in a prothrombin time between 15 and 20% of normal. At that time, patients were discharged from the hospital. Follow-up: At discharge, all patients received 2320 mg of aspirin daily as well as warfarin, but calcium antagonists and dipyridamole were not routinely continued. Therapy with oral anticoagulation was continued for 23 months. Patients were seen by their referring cardiologists at 1 and 3 months for clinical and stress electrocardiographic follow-up. All patients were readmitted for control angiography at 6 months. Angiographic analysis: All angiograms of the stent implantation procedure as well as 6-month control angiograms were reviewed by 2 independent operators at the Department of Cardiology, University Hospital Gasthuisberg, Leuven, Belgium. They were obtained in identical x-ray settings after intracoronary administration of nitroglycerin 200 pg. Because automated quantitative analysis of severely dissected arterial segments is quite problematic, the caliper method was selected to quantify coronary stenoses and dissection length, whereas the guiding catheter was used for calibration. The type of dissection was defined according to Dorros et a1.9Type A to C dissections were defined as suboptima1 results, and type D to F dissections as acute or threatened closure (Figure 2). Angiographic restenosis at 6-
FlGURE structure
1. The Wiktor and mounted
stent is a single on a conventional
tantalum wire over-thewire
TABLE
I Patient
and Lesion
Characteristics
(n = 69)
Male/female ratio Age (years) Arteries stented (no.) Left anterior descending Right coronary artery Left circumflex Left main stem Reference diameter (mm) Sent diameter (mm) Total occlusions (N) Dissection length (mm) TIMI flow before stenting
5.3 57 (29-84) 30 30 8 1 2.92 (2.2-4.5) 3.25 (3.0-4.0) 19 14.4 (2- 53.5) 1.9 (O-3)
Means (range) are given.
TIMI = Thrombolysls I” Myocardial Infarction trial.
month follow-up was defined as a visually estimated reduction in arterial diameter of >50%. Data collection and statistical analysis: Indications for stenting and procedural data were prospectively recorded by the operator in collaboration with a research coordinator. Clinical and laboratory data were also prospectively collected throughout hospitalization and the follow-up period and entered into a specific data form for each patient. Results are expressed as mean (range) or mean f 1 SD where appropriate. RESULTS Patients and lesion characteristics:
The relevant patient and lesion characteristics are given in Table I. Stents were implanted in 39 vessels <3 mm and in 30 vessels 23 mm in diameter. The ratio of the mean stent diameter to the mean reference diameter was 1.11
formed into a sinusoidal balloon catheter.
wave,
wrapped
into
a helical
coil
FIGURE 2. Distribution of the diierent types of dissections. A to C q suboptimal resultq D to F = acute or threatened closure.
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(3.2Y2.92). The mean length of the dissection was 14 mm, reflecting the fact that 45% of the dissections were actually longer than the implanted stent (Figure 3). Dissections were occlusive (Thrombolysis in Myocardial Infarction trial 0 flow) in 30% of the patients and 28% of the patients were treated with a stent for a suboptimal result. In only 20% of the patients, an autoperfusion balloon catheter was used before stenting, and only 12 of 69 patients (17%) received periprocedural intracoronary thrombolytic therapy. Finally, in 3 patients, 2 consecutive stents were implanted for long spiral dissections in the right coronary artery. Immediate results and complications Stent delivery was uneventful in 64 of the 69 patients including the 3 patients who had 2 consecutive stents implanted. In 5 patients it was impossible to cross the lesion with the stem/balloon catheter. Four of these 5 failures were observed in the left circumflex artery representing a 50% failure rate in this vessel. Stent retrieval was successful in 3 of these 5 patients; in 1 of these 3 patients a second stent was successfully implanted, whereas the 2 others were managed conservatively. In 2 patients, however, the device was lost in the femoral artery. In 1 of them the stent embolized into a small superficial side branch of the femoral artery, but subsequently a second stent was successfully implanted; the patient was managed conservatively and a patent side branch was seen at 6-month control angiography. In the other patient, the first stent embolized into the femoral artery; the second attempt, after improving guiding support, was also unsuccessful with stent loss in the proximal coronary artery. This patient was sent for emergency coronary artery surgery combined with stent removal from the femoral artery; both procedures were successful without complications. Thus, stent delivery in the dissected arterial segment was successful in 66 of the 69 patients, and a total of 69 stents were successfully implanted. However, another 2 patients were sent for emergency surgery because of progressive obstructive dissection with impaired runoff distal to the implanted stent. Therefore, 64 of the 69 patients (93%) left the catheterization room with a patent coronary artery
and without signs of ongoing ischemia. The myocardial area at risk was considered too large in another 5 patients, where it was decided to perform elective bypass surgery on the same day or the day after implantation. The mean hospital stay was 5.8 f 2.8 days for the remaining 59 patients. Significant bleeding problems necessitating transfusion occurred in 4 patients (6%): at the groin in 3 and gastrointestinal bleeding in 1, but cerebrovascular hemorrhage was not observed. (Sub)acute stent occlusion was documented in 10 patients (17%); in 3 it occurred after discharge from the hospital. Of these 10 patients with (sub)occlusions, 8 had vessels ~3 mm in diameter and 2 had occlusions in larger vessels. These thrombotic events were related to an activated thromboplastin time cl.5 the normal value in only 3 patients (2 also having bleeding complications) and to protocol violation in 1 patient (stent implanted in a patient treated for a chronic occlusion). Reocclusion was treated with repeat percutaneous transluminal coronary angioplasty (n = 3), emergency bypass surgery (n = 2) or in a conservative manner (n = 3); 2 patients died (3%). These 2 patients had the stent implanted in the proximal left anterior descending artery. Finally, 45 of the 69 patients (65%) had a successful stent implantation without major periprocedural complication (death, bypass surgery, stent thrombosis, bleeding requiring transfusion or Q-wave myocardial infarction). Short-term follow-up: Of the 57 patients eligible for follow-up (all patients except those who died or underwent coronary bypass surgery), 56 underwent control angiography at 6-month follow-up. Although only 5 patients (9%) experienced recurrent angina, a diameter narrowing within the stent of >50% was estimated in 15 of 56 patients. In vessels ~3 and 23 mm in diameter the restenosis rate was similar (27 and 26%, respectively). In the remaining 41 patients, where no angiographic restenosis was found, the range of intrastent diameter narrowing varied from -10 to +50% (mean 23), reflecting some degree of tissue proliferation in most of the stented segments. In 12 patients, restenosis was suc-
FlOURE 3. A, a single Wiktor stent is implanted in a large dissection of the proximal artery. Arrow points to an intimal flap protruding into the lumen distal to the stent. month follow-up showing the healing of the intimal flap.
left anterior descending 6, control anaogram at &
WIKTOR STENT AS BAILOUT DEVICE 739
cessfully treated with repeat angioplasty, but 3 patients with multivessel disease were referred for elective surgery. DISCUSSION The present study reports the initial multicenter experience with the new radiopaque balloon-expandable Wiktor stent during bailout situations in patients with dissections after coronary balloon angioplasty. The study group consisted of 69 patients with either suboptimal result (28%) or threatened (42%) or total (30%) vessel closure after coronary angioplasty. Although 45% of the treated dissections exceeded the length of the stent, multiple stenting was performed in only 3 patients, indicating that in the majority of the long dissections, 1 judiciously located stent will restore adequate blood flow. Implantation successrate (95%) was comparable to other stent devices.2*3*10However, bailout stenting for dissections of the left circumtlex artery was initially a problem: Failure to cross the lesion with the stent delivery system was indeed observed in 4 of 8 patients (50%), while stent embolism, 1 in the coronary artery and 2 in the femoral artery, was also observed during stenting attempts of the left circumflex artery. However, the investigators soon judged that this problem was largely eliminated when using an Amplatz-type guiding catheter for this vessel. Radiopacity of the device was considered a major advantage by most of the investigators, especially during a stressful emergency procedure. However, radiopacity hampered the exact visual interpretation of the poststent angiogram. In most cases a hazy appearance of the stent lumen was seen, which made it more difficult to distinguish residual protruding flaps or intraluminal thrombus. The rate of thrombosis (17%) and significant bleeding (6%) was comparable to the rates observed with similar bailout devices and is therefore still unacceptably high.2A However, this high rethrombosis rate was clearly influenced by the inclusion of a substantial number of vessels <3 mm, a subgroup traditionally considered inappropriate for stenting. A more rigid anticoagulation scheme and more specific monitoring (prothrombin fragments?) combined with the use of heparin-coated stents are expected to reduce these complication rates. An increasing body of evidence suggests that stenting has the potential to reduce the restenosis rate. Our clinical restenosis rate was only 9%, whereas after coronary angioplasty an incidence of roughly 25% has been reported. Although our 6-month angiographic data are hampered by the lack of quantification, a >50% narrowing at the implantation site was estimated in only 27% of the patients, which compares favorably with the 38% when the same criterion is used after dissections have been sealed with balloon inflations alone.” Kuntz et all2 previously demonstrated that the lower restenosis rate after stenting is due not to a decrease in intimal hyperplasia but to a larger post-treatment lumen diameter: In the present study the implanted stents were oversized by 11%. Consequently, our follow-up data further support the concept that stenting may reduce the restenosis rate.
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THE AMERICAN JOURNAL OF CARDIOLOGY VOLUME 73
Clinical implications: Bailout stenting with the new radiopaque Wiktor stent for the treatment of (sub)ocelusive dissections in native coronary arteries is feasible. Although the radiopacity of the stent was an advantageous feature in bailout situations, thrombosis and bleeding events were observed at rates comparable to those reported for earlier bailout devices and continue to limit their safety and efficacy rates. Therefore, a strategy of elective bypass surgery could be considered after stenting arteries that supply large myocardial areas. Further refinements in the anticoagulation protocols and newer stent devices intended to reduce these complication rates (heparin- or hirudin-coated, and biodegradable) are mandatory before general application of this bailout technique can be recommended. Acknowledgment: We are indebted to Joke Tack for expert manuscript preparation, and to Toon van der Krieken, Research Coordinator, Bakken Research Center, Maastricht, the Netherlands.
APPENDIX The following institutions and investigators participated in the European Wiktor Stent Study. The number of patients treated at each center is given in parentheses. The University Hospital Gasthuisberg, Leuven, Belgium (n = 36): J. Piessens, MD, M. Vrolix, MD, and I. De Scheerder, MD; The Free University of Berlin Rudolf Virchow, Berlin, Germany (n = 17): W Rutsch, MD, J. Bott, MD; The University Hospital Frankfurt, Frankfurt, Germany (n = 14): G. Kober, MD, W Burger, MD, H. Sieve& MD, R. Schrader, MD, C. Vallbracht, MD; Catharina Clinic Eindhoven, Eindhoven, the Netherlands (n = 4): M. El Gamal, MD, E Bracke, MD, H. Bonnier, MD; University Hospital Homburg&tar, Homburg/Saar, Germany (n = 4): J. Dijckmans, MD, C. Ozbek, MD; University Hospital Rotterdam, Rotterdam, the Netherlands (n = 4): P.W Serruys, MD, P. de Jaegere, MD, P de Feyter, MD, H. Suryapranata, MD; C.H.U. Rangueil, Toulouse, France (n = 3): J. Puel, MD; Georg August University Giittingen, Giittingen (n = 2): V Wiegand, MD, A. Buchwald, MD; U.C.V. Hospital La Casamance Marseille, Marseille, France (n = 2): P Labrunnie, MD, B. Valeix, MD; Cardiology Hospital C.H.R. Lille, Lille, France (n = 1): M. Bertrand, MD, E Leroy, MD. 1. Sigwart U, Urban P, Golf S, Kaufmann U, Imbert C, Fisher A. Kappenberger L. Emergency stenting for acute occlusion after coronary balloon angioplasty. Circulafion 1988;78:1121-1127. 2. Haude M, Erbel R, Staub U, Dietz U, Schatz R, Meyer J. Results of inbacomrxuy stents for management of coronary dissection after balloon angioplasty. Am J Cardiol 1991:67:6914596. 3. Roubin GS, Cannon AD, Argrawal SK, Macander PJ, Dean LS, Barley WA, B&and J. lntracoronary stenting for acute and threatened closure complicating percutaneous transluminal coronary angioplasty. Circularion 1992$5:911%X27. 4. Reifart N, Langer A, StGrger H, Schwarz F, Preusler W, Hofmann M. Strecker stem as a bail-out device following percutaneous transluminal coronary angioplasty. .I Intervent Cardiol 1992579-83. S. yan der Giessen WJ, Sermys PW, van Beusekom HMM, Van Woerkens LJ, van Loon H. Strauss BH. Coronary stenting with a new, radiopaque, balloon-expandable endopmsthesis in pigs. Circularion 1991;93: 1788-1798. 6. de Jaegere P, Sermys PW, Bertrand M, Wiegand V, Kober G, Marquis JF, Valeix B, Uebis R, Piessens J. Wiktor stem implantation in patients with restenosis following balloon angioplasty of a native coronary artery. Am J Cardiol 1992;69: 598-602.
APRIL 15, 1994
7. Buchwald A, Unterberg C, Werner G, Voth E, Kreuger H, Wiegand V. Initial clinical results with the Wiktor stem: a new balloon-expandable coronary stent. Ch Cardiol 1991;14:374-379. 8. de Jaegere PP, Sermys PW, Bertrand M, Wiegand V, Kober G, Marquis JF, Valeix B, Uebis R, Piessens J. Wiktor stent implantation in patients with restenosis following balloon angioplasty of a native coronary artery. Am J Car&l 1992;69:59&602. S. Dorros G, Cowley MJ, Simpson J, Bentivoglio LG, Block PC, Bourassa M, Detre K, Gosselin AJ, Gmntzig AR, Kelsey SF, Kent KM, Mock MB, Mullin SM. Passamani ER, Stenzer SH, Williams DO. Percutaneous transluminal coronary angioplasty: report of complications from the National Heart, Lung, and Blood
Institute FTCA Registry. Circularion 1983;67:723-730. 10. Talley JD, Weintraub WS, Roubin GS, Douglas JS Jr, Anderson HV, Jones EL, Morris DC, Lebemun HA, Craver JM, Guyton RA, King SB III. Failed elective percutaneous tmnsluminal coronary angioplasty requiring coronary artery bypass surgery: in-hospital and late clinical outcome at 5 years. Circularion 1990$2: 1203-1213. il. Sinclair IN, McCabe CH, Sipperly ME, Bairn DS. Predictors, therapeutic options and long-term outcome of abrupt reclosure. Am J Cardiol 3988;61:61(3-666. 12. Kuntz RE, Safran RD, Levine MS, Reis GJ, Diver DJ, Bairn DS. Novel approach to the analysis of restenosis after the use of three new coronary devices. J Am Cd Cardiol 1992;19: 1493-1499.
WIKTOR STENT AS BAILOUT DEVICE 741
The purpose of this study was to determine the results of the first Wiktor stent implantations in bailout conditions. From December 1999 to July 1991, in a total of 10 centers, 69 patients presenting with threatened or total closure after balloon angmplasty each received the Wiktor stemt in 1 coronary artery. In these 69 coronary arteries, a total of 72 stent deliveries were attempted and 69 were successful (delivery sue cess rate 95%). Delivery failure was treated conservatively in 2 patients and surgically in 1 patient. Emergency surgery was also performed in 2 patients, who after successful stent delivery showed progressive distal extension of the dissection. In addition, 5 patients underwent elective surgery to avoid the possibllity of stent thrombosis because the myocardial area at risk was considered too large. Postprocedural blood transfusion was pehrmed in 6% of the patient& whereas stent thrombosis occurred in 10 of 59 patients (17%), resulting in 2 deaths. Finally, 65% of the patients had a successful stent implantation without major periprccedural complications. At &month followup, only 9% of the patients experienced recurrent angina, whereas a ~59% arterial diameter narrowing was observed in 27% of the patients. Thus, the radlopaque Wlktor stent can be accurately and conveniently implanted in dissected coronary arterial segments. However, as for similar bailout devices, the number of thrombotic and bleeding events remains high. (Am J Cardiol1994;73:737-741)
From the European Wiktor Stent Study Centers (see Appendix). Manuscript received July 6, 1993; revised manuscript received September 17, 1993, and accepted September 21. Address for reprints: Jan Piessens, MD, Department of Cardiology, University Hospital Gasthuisberg, Herestraat 49, B 3000 Leuven, Belgium. *See Appendix
for list of participants
in the Wiktor
Stent Study.
I
ntracoronary stents have recently been developed to reduce the problems of acute reocclusion complicating coronary angioplasty. For this purpose, 2 types of stents, either self-expandable or balloon-expandable, have been tested in several clinical trials.lA A large body of experimental and clinical evidence indicates the efficacy of these devices but, at the present time, the technique remains limited by poor fluoroscopic visibility and by the thrombogenic potential of the devices. Recently, a new radiopaque tantalum stent, the WiktorB stent, became available in Europe for clinical use.5-8 This study presents the first multicenter experience using this stent to manage acute or threatened vessel closure. METHODS Balloouexpsndable intracoronary stent: The balloon-expandable stent used in the present study (W&or, Medtronic, Inc., Minneapolis, Minnesota) is constructed of a single tantalum wire (diameter 0.127 mm), which is formed into a sinusoidal wave and wrapped into a helical coil structure. The prosthesis, 15 f 2 mm long, is premounted on a polyethylene balloon of a standard angioplasty catheter (Figure 1). The device was used under the Food and Drug Administration investigational device exemption status as part of a multicenter study, and the study was approved by the ethical committee of each participating institution. Patients: From December 1990 through July 1991, intracoronary stenting was attempted in 69 consecutive patients (11 women and 58 men), all presenting with acute or threatened vessel closure accompanied by anginal pain or ischemic electrocardiographic changes, or both, during or after balloon angioplasty. The study protocol allowed stenting in all 3 major coronary arteries; venous grafts as well as chronic occlusions were excluded. All patients gave written informed consent for stent implantation and 6-month control angiography. Procedure: Stent implantations were performed as previously described.8 Because implantations were performed under bailout conditions, premeditation consisted of only 500 mg of oral or intravenous aspirin and an intravenous bolus of 10,000 IU of heparin in addition to the routine dose used during coronary angioplasty in each individual center. An infusion of dextran 40 (1,000 ml) at a rate of 100 ml/hour was begun just before stent implantation, while the routine heparin infusion at 1,000 IU/hour was continued. Implantation of 1 single stent was recommended for long dissections, but the exact location of the stent and the administration of thrombolytic therapy were left to the discretion of the operator. The intraarterial sheath was removed 4 to 8 hours after im-
WIKTOR STENTAS BAILOUT DEVICE 737
plantation at a time when, after interruption of the heparin infusion, the activated partial thromboplastin time was ~80 seconds; the heparin infusion was restarted 4 hours later and monitored in order to maintain the partial thromboplastin time between 80 and 120 seconds. The heparin infusion was withheld as soon as warfarin treatment had resulted in a prothrombin time between 15 and 20% of normal. At that time, patients were discharged from the hospital. Follow-up: At discharge, all patients received 2320 mg of aspirin daily as well as warfarin, but calcium antagonists and dipyridamole were not routinely continued. Therapy with oral anticoagulation was continued for 23 months. Patients were seen by their referring cardiologists at 1 and 3 months for clinical and stress electrocardiographic follow-up. All patients were readmitted for control angiography at 6 months. Angiographic analysis: All angiograms of the stent implantation procedure as well as 6-month control angiograms were reviewed by 2 independent operators at the Department of Cardiology, University Hospital Gasthuisberg, Leuven, Belgium. They were obtained in identical x-ray settings after intracoronary administration of nitroglycerin 200 pg. Because automated quantitative analysis of severely dissected arterial segments is quite problematic, the caliper method was selected to quantify coronary stenoses and dissection length, whereas the guiding catheter was used for calibration. The type of dissection was defined according to Dorros et a1.9Type A to C dissections were defined as suboptima1 results, and type D to F dissections as acute or threatened closure (Figure 2). Angiographic restenosis at 6-
FlGURE structure
1. The Wiktor and mounted
stent is a single on a conventional
tantalum wire over-thewire
TABLE
I Patient
and Lesion
Characteristics
(n = 69)
Male/female ratio Age (years) Arteries stented (no.) Left anterior descending Right coronary artery Left circumflex Left main stem Reference diameter (mm) Sent diameter (mm) Total occlusions (N) Dissection length (mm) TIMI flow before stenting
5.3 57 (29-84) 30 30 8 1 2.92 (2.2-4.5) 3.25 (3.0-4.0) 19 14.4 (2- 53.5) 1.9 (O-3)
Means (range) are given.
TIMI = Thrombolysls I” Myocardial Infarction trial.
month follow-up was defined as a visually estimated reduction in arterial diameter of >50%. Data collection and statistical analysis: Indications for stenting and procedural data were prospectively recorded by the operator in collaboration with a research coordinator. Clinical and laboratory data were also prospectively collected throughout hospitalization and the follow-up period and entered into a specific data form for each patient. Results are expressed as mean (range) or mean f 1 SD where appropriate. RESULTS Patients and lesion characteristics:
The relevant patient and lesion characteristics are given in Table I. Stents were implanted in 39 vessels <3 mm and in 30 vessels 23 mm in diameter. The ratio of the mean stent diameter to the mean reference diameter was 1.11
formed into a sinusoidal balloon catheter.
wave,
wrapped
into
a helical
coil
FIGURE 2. Distribution of the diierent types of dissections. A to C q suboptimal resultq D to F = acute or threatened closure.
738
THE AMERICAN
JOURNAL
OF CARDIOLOGY
VOLUME
73
APRIL 15,1994
(3.2Y2.92). The mean length of the dissection was 14 mm, reflecting the fact that 45% of the dissections were actually longer than the implanted stent (Figure 3). Dissections were occlusive (Thrombolysis in Myocardial Infarction trial 0 flow) in 30% of the patients and 28% of the patients were treated with a stent for a suboptimal result. In only 20% of the patients, an autoperfusion balloon catheter was used before stenting, and only 12 of 69 patients (17%) received periprocedural intracoronary thrombolytic therapy. Finally, in 3 patients, 2 consecutive stents were implanted for long spiral dissections in the right coronary artery. Immediate results and complications Stent delivery was uneventful in 64 of the 69 patients including the 3 patients who had 2 consecutive stents implanted. In 5 patients it was impossible to cross the lesion with the stem/balloon catheter. Four of these 5 failures were observed in the left circumflex artery representing a 50% failure rate in this vessel. Stent retrieval was successful in 3 of these 5 patients; in 1 of these 3 patients a second stent was successfully implanted, whereas the 2 others were managed conservatively. In 2 patients, however, the device was lost in the femoral artery. In 1 of them the stent embolized into a small superficial side branch of the femoral artery, but subsequently a second stent was successfully implanted; the patient was managed conservatively and a patent side branch was seen at 6-month control angiography. In the other patient, the first stent embolized into the femoral artery; the second attempt, after improving guiding support, was also unsuccessful with stent loss in the proximal coronary artery. This patient was sent for emergency coronary artery surgery combined with stent removal from the femoral artery; both procedures were successful without complications. Thus, stent delivery in the dissected arterial segment was successful in 66 of the 69 patients, and a total of 69 stents were successfully implanted. However, another 2 patients were sent for emergency surgery because of progressive obstructive dissection with impaired runoff distal to the implanted stent. Therefore, 64 of the 69 patients (93%) left the catheterization room with a patent coronary artery
and without signs of ongoing ischemia. The myocardial area at risk was considered too large in another 5 patients, where it was decided to perform elective bypass surgery on the same day or the day after implantation. The mean hospital stay was 5.8 f 2.8 days for the remaining 59 patients. Significant bleeding problems necessitating transfusion occurred in 4 patients (6%): at the groin in 3 and gastrointestinal bleeding in 1, but cerebrovascular hemorrhage was not observed. (Sub)acute stent occlusion was documented in 10 patients (17%); in 3 it occurred after discharge from the hospital. Of these 10 patients with (sub)occlusions, 8 had vessels ~3 mm in diameter and 2 had occlusions in larger vessels. These thrombotic events were related to an activated thromboplastin time cl.5 the normal value in only 3 patients (2 also having bleeding complications) and to protocol violation in 1 patient (stent implanted in a patient treated for a chronic occlusion). Reocclusion was treated with repeat percutaneous transluminal coronary angioplasty (n = 3), emergency bypass surgery (n = 2) or in a conservative manner (n = 3); 2 patients died (3%). These 2 patients had the stent implanted in the proximal left anterior descending artery. Finally, 45 of the 69 patients (65%) had a successful stent implantation without major periprocedural complication (death, bypass surgery, stent thrombosis, bleeding requiring transfusion or Q-wave myocardial infarction). Short-term follow-up: Of the 57 patients eligible for follow-up (all patients except those who died or underwent coronary bypass surgery), 56 underwent control angiography at 6-month follow-up. Although only 5 patients (9%) experienced recurrent angina, a diameter narrowing within the stent of >50% was estimated in 15 of 56 patients. In vessels ~3 and 23 mm in diameter the restenosis rate was similar (27 and 26%, respectively). In the remaining 41 patients, where no angiographic restenosis was found, the range of intrastent diameter narrowing varied from -10 to +50% (mean 23), reflecting some degree of tissue proliferation in most of the stented segments. In 12 patients, restenosis was suc-
FlOURE 3. A, a single Wiktor stent is implanted in a large dissection of the proximal artery. Arrow points to an intimal flap protruding into the lumen distal to the stent. month follow-up showing the healing of the intimal flap.
left anterior descending 6, control anaogram at &
WIKTOR STENT AS BAILOUT DEVICE 739
cessfully treated with repeat angioplasty, but 3 patients with multivessel disease were referred for elective surgery. DISCUSSION The present study reports the initial multicenter experience with the new radiopaque balloon-expandable Wiktor stent during bailout situations in patients with dissections after coronary balloon angioplasty. The study group consisted of 69 patients with either suboptimal result (28%) or threatened (42%) or total (30%) vessel closure after coronary angioplasty. Although 45% of the treated dissections exceeded the length of the stent, multiple stenting was performed in only 3 patients, indicating that in the majority of the long dissections, 1 judiciously located stent will restore adequate blood flow. Implantation successrate (95%) was comparable to other stent devices.2*3*10However, bailout stenting for dissections of the left circumtlex artery was initially a problem: Failure to cross the lesion with the stent delivery system was indeed observed in 4 of 8 patients (50%), while stent embolism, 1 in the coronary artery and 2 in the femoral artery, was also observed during stenting attempts of the left circumflex artery. However, the investigators soon judged that this problem was largely eliminated when using an Amplatz-type guiding catheter for this vessel. Radiopacity of the device was considered a major advantage by most of the investigators, especially during a stressful emergency procedure. However, radiopacity hampered the exact visual interpretation of the poststent angiogram. In most cases a hazy appearance of the stent lumen was seen, which made it more difficult to distinguish residual protruding flaps or intraluminal thrombus. The rate of thrombosis (17%) and significant bleeding (6%) was comparable to the rates observed with similar bailout devices and is therefore still unacceptably high.2A However, this high rethrombosis rate was clearly influenced by the inclusion of a substantial number of vessels <3 mm, a subgroup traditionally considered inappropriate for stenting. A more rigid anticoagulation scheme and more specific monitoring (prothrombin fragments?) combined with the use of heparin-coated stents are expected to reduce these complication rates. An increasing body of evidence suggests that stenting has the potential to reduce the restenosis rate. Our clinical restenosis rate was only 9%, whereas after coronary angioplasty an incidence of roughly 25% has been reported. Although our 6-month angiographic data are hampered by the lack of quantification, a >50% narrowing at the implantation site was estimated in only 27% of the patients, which compares favorably with the 38% when the same criterion is used after dissections have been sealed with balloon inflations alone.” Kuntz et all2 previously demonstrated that the lower restenosis rate after stenting is due not to a decrease in intimal hyperplasia but to a larger post-treatment lumen diameter: In the present study the implanted stents were oversized by 11%. Consequently, our follow-up data further support the concept that stenting may reduce the restenosis rate.
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Clinical implications: Bailout stenting with the new radiopaque Wiktor stent for the treatment of (sub)ocelusive dissections in native coronary arteries is feasible. Although the radiopacity of the stent was an advantageous feature in bailout situations, thrombosis and bleeding events were observed at rates comparable to those reported for earlier bailout devices and continue to limit their safety and efficacy rates. Therefore, a strategy of elective bypass surgery could be considered after stenting arteries that supply large myocardial areas. Further refinements in the anticoagulation protocols and newer stent devices intended to reduce these complication rates (heparin- or hirudin-coated, and biodegradable) are mandatory before general application of this bailout technique can be recommended. Acknowledgment: We are indebted to Joke Tack for expert manuscript preparation, and to Toon van der Krieken, Research Coordinator, Bakken Research Center, Maastricht, the Netherlands.
APPENDIX The following institutions and investigators participated in the European Wiktor Stent Study. The number of patients treated at each center is given in parentheses. The University Hospital Gasthuisberg, Leuven, Belgium (n = 36): J. Piessens, MD, M. Vrolix, MD, and I. De Scheerder, MD; The Free University of Berlin Rudolf Virchow, Berlin, Germany (n = 17): W Rutsch, MD, J. Bott, MD; The University Hospital Frankfurt, Frankfurt, Germany (n = 14): G. Kober, MD, W Burger, MD, H. Sieve& MD, R. Schrader, MD, C. Vallbracht, MD; Catharina Clinic Eindhoven, Eindhoven, the Netherlands (n = 4): M. El Gamal, MD, E Bracke, MD, H. Bonnier, MD; University Hospital Homburg&tar, Homburg/Saar, Germany (n = 4): J. Dijckmans, MD, C. Ozbek, MD; University Hospital Rotterdam, Rotterdam, the Netherlands (n = 4): P.W Serruys, MD, P. de Jaegere, MD, P de Feyter, MD, H. Suryapranata, MD; C.H.U. Rangueil, Toulouse, France (n = 3): J. Puel, MD; Georg August University Giittingen, Giittingen (n = 2): V Wiegand, MD, A. Buchwald, MD; U.C.V. Hospital La Casamance Marseille, Marseille, France (n = 2): P Labrunnie, MD, B. Valeix, MD; Cardiology Hospital C.H.R. Lille, Lille, France (n = 1): M. Bertrand, MD, E Leroy, MD. 1. Sigwart U, Urban P, Golf S, Kaufmann U, Imbert C, Fisher A. Kappenberger L. Emergency stenting for acute occlusion after coronary balloon angioplasty. Circulafion 1988;78:1121-1127. 2. Haude M, Erbel R, Staub U, Dietz U, Schatz R, Meyer J. Results of inbacomrxuy stents for management of coronary dissection after balloon angioplasty. Am J Cardiol 1991:67:6914596. 3. Roubin GS, Cannon AD, Argrawal SK, Macander PJ, Dean LS, Barley WA, B&and J. lntracoronary stenting for acute and threatened closure complicating percutaneous transluminal coronary angioplasty. Circularion 1992$5:911%X27. 4. Reifart N, Langer A, StGrger H, Schwarz F, Preusler W, Hofmann M. Strecker stem as a bail-out device following percutaneous transluminal coronary angioplasty. .I Intervent Cardiol 1992579-83. S. yan der Giessen WJ, Sermys PW, van Beusekom HMM, Van Woerkens LJ, van Loon H. Strauss BH. Coronary stenting with a new, radiopaque, balloon-expandable endopmsthesis in pigs. Circularion 1991;93: 1788-1798. 6. de Jaegere P, Sermys PW, Bertrand M, Wiegand V, Kober G, Marquis JF, Valeix B, Uebis R, Piessens J. Wiktor stem implantation in patients with restenosis following balloon angioplasty of a native coronary artery. Am J Cardiol 1992;69: 598-602.
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7. Buchwald A, Unterberg C, Werner G, Voth E, Kreuger H, Wiegand V. Initial clinical results with the Wiktor stem: a new balloon-expandable coronary stent. Ch Cardiol 1991;14:374-379. 8. de Jaegere PP, Sermys PW, Bertrand M, Wiegand V, Kober G, Marquis JF, Valeix B, Uebis R, Piessens J. Wiktor stent implantation in patients with restenosis following balloon angioplasty of a native coronary artery. Am J Car&l 1992;69:59&602. S. Dorros G, Cowley MJ, Simpson J, Bentivoglio LG, Block PC, Bourassa M, Detre K, Gosselin AJ, Gmntzig AR, Kelsey SF, Kent KM, Mock MB, Mullin SM. Passamani ER, Stenzer SH, Williams DO. Percutaneous transluminal coronary angioplasty: report of complications from the National Heart, Lung, and Blood
Institute FTCA Registry. Circularion 1983;67:723-730. 10. Talley JD, Weintraub WS, Roubin GS, Douglas JS Jr, Anderson HV, Jones EL, Morris DC, Lebemun HA, Craver JM, Guyton RA, King SB III. Failed elective percutaneous tmnsluminal coronary angioplasty requiring coronary artery bypass surgery: in-hospital and late clinical outcome at 5 years. Circularion 1990$2: 1203-1213. il. Sinclair IN, McCabe CH, Sipperly ME, Bairn DS. Predictors, therapeutic options and long-term outcome of abrupt reclosure. Am J Cardiol 3988;61:61(3-666. 12. Kuntz RE, Safran RD, Levine MS, Reis GJ, Diver DJ, Bairn DS. Novel approach to the analysis of restenosis after the use of three new coronary devices. J Am Cd Cardiol 1992;19: 1493-1499.
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