Coronary stenting reduces restenosis significantly compared with balloon angioplasty (1 – 3). As stent use has increased remarkably, in-stent restenosis is now an important clinical problem which may occur in 15% to 30% of cases. Recently, it was reported that coronary stent implantation can be performed safely without previous dilatation (4 – 13). This approach can shorten procedural duration and fluoroscopy time (4, 5). Furthermore, there is a decreased utilisation of contrast agent, balloons and wires (13). The recent experimental evidence indicates that the extent of vessel wall injury as the result of multiple balloon dilatations could negatively affect restenosis (14). This single-center, prospective, observational study describes the immediate and long-term angiographic and clinical results of direct coronary stenting.

From January 1998 until July 2000, one thousand three hundred and five patients were treated by PTCA at our institution and 881 stents were implanted. Out of these 1305 consecutive patients, one hundred and ninety-four patients (15%) were treated with direct stent implantation, without previous dilatation.

There were 126 men and 68 women, mean age 58 ± 9 years, in this study. The indications for coronary intervention were stable angina (114 patients; 59%), unstable angina (71 patients; 36%) and acute myocardial infarction (nine patients; 5%).

The decision regarding whether to attempt direct coronary stenting was made immediately after taking a coronary angiogram. Inclusion criteria were clinical diagnosis of an acute or chronic form of coronary artery disease, de novo coronary lesion with stenosis of more than 50% of luminal diameter according to quantitative coronary analysis (DCI-S, Automated Coronary Analysis, Philips), coronary lesions being in proximal or middle segments, absence of heavily calcified treated coronary arteries (assessed by fluoroscopy), TIMI flow 2 or 3, and absence of excessive tortuosity of proximal segment of the treated artery. The reference luminal diameter and the length of lesion had to be > 3 mm and < 25 mm, respectively. Lesions of type C or multi-vessel coronary disease were not contraindications for direct stenting. The final decision to treat the lesion by direct coronary stenting was made by two experienced operators (J.V. and D.T.).

Informed consent to participate in this study was obtained from each patient.

Quantitative variables are expressed as the mean value ± SD and were compared by Student t test. Significance was set at a value of p < 0.05.

The procedure and fluoroscopy times were measured during interventions alone; time of diagnostic procedure was not included.

The anticoagulant and antithrombotic protocol comprised administration of 200 – 500 mg of aspirin before the procedure and was continued indefinitely. Intra-arterial administration of heparin bolus at the beginning of the procedure (100 IU/kg body weight) maintained an activation clotting time of 300 – 350 seconds. Ticlopidine treatment was started on the day of the procedure (500 mg twice a day for 2 days) and maintained for one month (at a dose of 250 mg twice a day). Glycoprotein IIb/IIIa inhibitors were not used in this study. The arterial sheath was removed 6 hours after the procedure. Hemostasis was achieved by manual compression. ECG was recorded immediately after the procedure and on the next day. Creatine kinase and myocardial iso-enzyme levels were obtained in case of clinical symptomatology or ECG changes. Troponin levels were not followed. Patients treated for stable angina were discharged on the following day.

One hundred and twelve successfully treated patients (59%) who refused repeated coronary angiography examination (Group B) were contacted by telephone, questionnaire or office visit more than 9 months after the procedure. The occurrence of major late clinical events (death, acute myocardial infarction, target lesion revascularization, coronary revascularization, stroke) was recorded. Events were subsequently source-documented.

Early results

Coronary stenting was performed in 194 patients and 195 lesions in proximal or mid segments of coronary arteries. A total of 199 stents were implanted. A single stent was used in 189 patients; two stents were electively used in one patient. In four patients (2%) another stent implantation was performed due to major intimal dissection.

Stenting without predilatation was successful in 189 patients (97%). In five patients (3%) attempts at direct stenting were unsuccessful (in four cases lesion of type B2, in one case lesion of type C). In all these cases it was impossible to advance stents to the target lesions. Probably, calcifications of the target lesions (three cases) and decreased backup of chosen guiding catheters (Judkins left catheter in these two cases) were the reasons of failed attempts. Stents which could not be implanted directly were all retrieved without complications and were successfully implanted after balloon angioplasty. An additional post-dilatation was performed in nine patients (5%) for residual stenosis of greater than 20%.

Mean reference luminal diameter measured before intervention was 3.4 ± 0.3 mm, minimal luminal diameter 0.8 ± 0.3 mm, stenosis diameter 78 ± 10% and length of lesion 12.9 ± 5.8 mm. The mean procedure time was 13.1 ± 8.5 min and the fluoroscopic time was 3.8 ± 2.5 min. Coronary stenting was performed by Jomed Delivery System in 154 cases. Other stents used were Coroflex in 13 lesions, AVE GFX in 12 lesions, MultiLink in 12 lesions, CrossFlex in four lesions, Paragon in three lesions, and NIR in one lesion. Mean length of stent was 16.8 ± 4.4 mm. Mean diameter of balloon catheter at nominal inflation pressure was 3.4 ± 0.3 mm. Mean residual stenosis after intervention was 5 ± 9%. There were no significant differences between procedural characteristics of the total group of patients and group A and B.

There were no distal embolizations related to the treatment of lesions containing intraluminal thrombus. All stents remained premounted till the moment of implantation. Complications, such as no-reflow phenomenon, abrupt closure of the treated artery, severe arrhythmia, major bleeding, stent thrombosis or cerebrovascular accident did not occur. No patient underwent a subsequent urgent revascularization. Acute occlusion of the first septal perforator resulted in acute Q-wave myocardial infarction in one case. No patient died.

Clinical events

All angiographic data are summarized in Table 4.

Angina pectoris at follow-up was graded according to the Canadian Cardiovascular Society (CCS) classification and revealed from class 2.7 ± 1.2 to 0.8 ± 0.8 (p < 0.001).

Most authors do not consider the severity of the stenosis being a reliable predictor of failure of stent implantation. Although most lesions treated by stenting without predilatation had lower luminal diameters than diameters of premounted low-profile stents, preservation of elasticity of a vessel wall at the site of intervention might play an important role in the placement of a stent into a tight stenosis. Poor elasticity could be a reason for unsatisfactory results being obtained when one is treating calcified lesions using this technique. Another fact is that some lesions contain a soft intraluminal thromboses that are simple to cross (6, 7, 12). The presence of intracoronary thrombosis is typical of acute coronary syndromes. Similarly, restenotic lesions and mainly saphenous vein grafts are in the clinical practice often stented without predilatation, because they are smooth and free of calcified and hard atheroma. Although 38% of patients presented in our study with acute coronary syndromes there were no occurrences of distal embolization or no-reflow phenomenon during and after direct stent implantation. In the study by Hamon et al. (6), there was also a low (2.5%) incidence of no-reflow phenomenon observed in the population of patients stented directly for acute coronary syndrome. On the other hand, Piana et al. (15) reported even a 12% incidence of no-reflow phenomenon in patients undergoing coronary interventions for acute coronary syndromes. The recent study by Vallejo et al. (16) examined the incidence of no-reflow in the population of elective interventions and direct angioplasties. The overall incidence of no-reflow for the two modalities was 5.2% (16.1% for direct angioplasty and 1.9% for elective angioplasty). These studies show that the no-reflow phenomenon is not uncommon after angioplasty. We assume that the administration of a glycoprotein IIb/IIIa receptor inhibitor and direct coronary stenting might be a promising way in the prevention and treatment of the no-reflow phenomenon.

Most authors have suggested using low-profile tubular stents, extra-support guidewires and/or extra-back-up guiding catheters for direct stenting. We can support these recommendations. However, Oemrawsingh et al. (9) did not use extra-back-up catheters and wires and they performed direct stenting with a success rate of 90%. Thus, it seems to be probable that an experienced interventional cardiologist can select a suitable lesion and instruments for direct stenting with a high probability of successful procedure.

Relatively high values of radiation exposure have been considered a necessary consequence of cardiac angiographic procedures. Recently, Cusma et al. (17) showed that patient and staff radiation exposures during cardiac catheterization procedures have increased as a result of the increased complexity of the angiographic procedures performed in current clinical practice. Some procedural variables such as the fluoroscopy time are very difficult to be compared among different institutions. However, Cusma et al. demonstrated that a mean fluoroscopy time in a consecutive series of 972 patients was even 24.6 min for the coronary intervention (17). Briguori et al. performed a comparison between the group that underwent direct stenting and the group that underwent standard single-vessel stent implantation (4). They found a significant reduction of radiation exposure time (12 ± 9 vs 16 ± 10 min; p < 0.05). In our study, we revealed an ultra-short radiation exposure time (3.8 ± 2.5 min) associated with direct coronary stenting. These results cannot be directly compared but they suggested that direct stenting might be an attractive way to short interventional procedures in the future.

This study was based on quantitative coronary analysis and clinical follow-up. A better understanding of the concept of direct stenting would have been gained if intravascular ultrasound had been used in all cases. On the other hand, the intravascular ultrasound study by Legutko et al. (22) revealed that there is no difference in expansion and aposition of stents between direct stenting and stenting after predilatation. Similarly, de la Torre Hernandez et al. (23) showed that direct stenting in selected lesions provides angiographic and ultrasonographic results that could be comparable to those expected with conventional stenting. It should be kept in mind that performance of direct stenting does not preclude evaluation of the final result by intravascular ultrasound and post-dilatation, if necessary (4).

Selection of appropriate lesions for direct stenting is of crucial importance. The reason for the good early and late results of this study might be the selection of lesions convenient for this approach.

We cannot recommend direct stenting of heavily calcified lesions, long lesions and total occlusions without a distal coronary flow. For complex lesions we should use guidewires and guiding catheters with higher support and backup. We should take in account that in case of intervention of a tight lesion the ability of exact stent positioning is decreased because the coronary flow is considerably compromised by the stent. It might be very important if correct stent positioning is crucial, such as when a side branch must be avoided.

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17. Cusma JT, Bell MR, Wondrow MA, et al. Real-time measurement of radiation exposure to patients during diagnostic coronary angiography and percutaneous interventional procedures. J Am Coll Cardiol 1999;33:427–435.

18. de Feyter PJ, Kay P, Disco C, et al. Reference chart derived from post-stent-implantation intravascular ultrasound predictors of 6-month expected restenosis on quantitative coronary angiography. Circulation 1999;100:1777–1783.

19. Serruys PW, Kay IP, Disco C, et al. Periprocedural quantitative angiography after Palmaz-Schatz stent implantation predicts the restenosis rate at six months: results of meta-analysis of the BElgian Netherlands Stent study (BENESTENT) I, BENESTENT II Pilot, BENESTENT II and MUSIC trials. J Am Coll Cardiol 1999;34:1067–1074.

20. Kornowski R, Mehran R, Satler LF, et al. Procedural results and late clinical outcomes following multivessel coronary stenting. J Am Coll Cardiol 1999;33:420–426.

21. Khalifé K, Citron B, Mourali S, et al. Is direct stenting a safe and effective therapy for a coronary artery stenting? Results of the randomized BET study. Eur Heart J 2000;21(Suppl.):264.

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