Asian Cardiovasc Thorac Ann 2004;12:291-295
© 2004 Asia Publishing EXchange Ltd
Excimer Laser Coronary Angioplasty in Acute Myocardial Infarction
Erdogan Ilkay, MD,
Ilgin Karaca, MD,
Mehmet Akbulut, MD,
A Erhan Kiliço
lu, MD,
Mustafa Yavuzkir, MD,
Nadi Arslan, MD
Department of Cardiology, Firat Medical School, Elaz, Turkey
For reprint information contact: Erdogan Ilkay, MD Tel: 90 424 238 8080 Fax: 90 424 238 8019 Email: ilkayerdogan{at}superonline.com Department of Cardiology, Firat Medical School, Zübeyde Hanim Cad. 116/6, Elazi, Turkey.
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ABSTRACT
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We evaluated the short-term results of percutaneous excimer laser angioplasty in acute myocardial infarction. Of the 18 patients studied, 2 were female and 16 male with a mean age of 56.6 ± 12.1 years. Thrombolysis in myocardial infarction grades 0, 1, and 2 flow was observed in 10, 5, and 3 cases, respectively, prior to the procedure. The degree of stenosis was 97.9% ± 5.1%. The lesion was crossed with a laser catheter in all cases, using a mean number of 808 ± 384 laser pulses. Type C dissection developed in only 1 case (6%). Except for this case, distal flow was grade 3 in all the patients. Following the procedure, ST segment resolution exceeding 70% was achieved in 14 cases (78%) within the first 90 minutes. The success rate of laser ablation was 94% (17 patients). Stent implantation was performed in all the cases. In conclusion, laser angioplasty is an effective and reliable treatment for acute myocardial infarction.
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INTRODUCTION
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Although primary coronary angioplasty for treating acute myocardial infarction (MI) has low mortality, recurrent MI and stroke, early recurrent ischemia, and late restenosis are important limitations.1 In 20% of cases, it is not possible to achieve thrombolysis in myocardial infarction (TIMI) grade 3 flow with primary angioplasty.2 In the rest, in which TIMI 3 flow can be established, sufficient myocardial perfusion cannot always be obtained. The main reason for this is thrombus dislocation and distal embolization during balloon angioplasty.
The application of excimer laser coronary angioplasty (ELCA) in acute MI is very new.3,4 It is believed that laser increases the effectiveness of angioplasty due to its lytic effect on the thrombus, in addition to its debulking effect on the atherosclerotic plaque beneath the thrombus. We report here the short-term results of percutaneous ELCA in acute MI.
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PATIENTS AND METHODS
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This study included 18 patients who underwent ELCA for acute MI. The 2 female and 16 male patients had a mean age of 56.6 ± 12.1 years. Written consent was obtained from the patients, and the study was conducted in accordance with the Helsinki Declaration.
Acute MI was diagnosed in the presence of persistent angina pectoris lasting longer than 20 minutes and ST segment elevation of 
1 mm in at least 2 standard leads or 2 mm in at least 2 continuous precordial leads. Diagnosis was confirmed by cardiac enzyme elevation to over twice the normal upper value.
The exclusion criteria for this study were onset of symptoms at least 12 hours earlier; left main coronary lesion; contraindication to the use of heparin, aspirin, ticlopidine, and clopidogrel; restenotic nature of the lesion causing the infarction; the need for rescue percutaneous transluminal coronary angioplasty (PTCA); the presence of dissection of type C or above on the angiogram; the presence of TIMI 3 flow in the infarct-related artery prior to the procedure; and previous coronary artery bypass surgery or previous MI.
All patients received aspirin and ticlopidine before ELCA, as well as a heparin bolus or infusion to increase the activated clotting time to 300 seconds. Intracoronary nitroglycerin was administered whenever required during the procedure. The minimum lumen diameter (MLD) was determined by quantitative angiographic analysis before and after ELCA and after stenting.
Thrombosis was defined as the presence of a discrete intraluminal clot with defined borders with or without associated contrast staining. Coronary flow in the infarct vessel was graded using the classification of the Thrombolysis in Myocardial Infarction study.5 Total coronary occlusion was defined as having an MLD of 0 mm and 100% stenosis. Coronary dissection from angioplasty was graded according to the classification of Huber and colleagues,6 with type A or B for minor dissection and C or above for major dissection.
A pulsed xenon chloride excimer laser with a wavelength of 308 nm (Spectranetics CVX-300; Spectranetics, Colorado Springs, CO, USA) was used with a pulse duration of 135 nsec and energy output of 200 mJ/pulse. Energy was delivered via rapid exchange catheters containing flexible optic fibers. Two catheters with diameters of 1.4 and 1.7 mm and a concentric tip configuration were used (Vitesse C; Spectranetics, Colorado Springs, CO, USA). Lasing energy was set at a fluence of 45 mJ·mm–2 and a repetition rate of 25 Hz. The diameter of the laser catheter to be used was decided by the operator according to the target lesion morphology and the degree of stenosis. Safe lasing techniques were used, which required an assistant injecting saline at 2 to 3 mL·sec–1 during laser activation while the operator advanced the laser catheter at a speed of 0.5 mm·sec–1 through the lesion, as well as retrieval of the laser catheter from the irradiated lesion into a guiding catheter after every 2 laser trains.7,8
The success of laser ablation was defined as the ability to cross the lesion by the laser catheter, the absence of major dissection and perforation, a 20% reduction in stenosis after laser, and achieving distal TIMI 3 flow. The success of the procedure was defined as having residual stenosis of 
= 20% after the procedure, the absence of perforation and major dissection, patient survival, the absence of reinfarction (Q or non-Q wave MI), and no requirement for revascularization (coronary bypass surgery, PTCA) while in the hospital.
Data are expressed as mean ± standard deviation. Mean values were analyzed by the paired t test, while pre- and post-ELCA MLD measurements were compared with repeated analysis of variance. The limit for meaningfulness was determined as 0.033 for post-hoc comparisons. Statistical significance is defined as p < 0.05.
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RESULTS
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Table 1
shows the main characteristics of the patients. Q wave MI occurred in 17 patients (94%), while non-Q wave MI occurred in 1 patient. All but 2 patients had echocardiography before the procedure, and mean left ventricular ejection fraction was 52.4% ± 9.6%. The interval between onset of symptoms and laser application was 234 ± 29 minutes, and the interval between arrival at the hospital and laser application was 23 ± 11 minutes. Ventricular fibrillation developed in 1 patient just before the procedure, which resumed after defibrillation. After ELCA, no recurrent arrhythmia was observed and this patient was discharged on day 6.
Before undergoing the procedure, all the patients had thrombosis, with 67% of the lesions being diagnosed as total occlusion (Table 2). TIMI 0 flow was observed in 10 cases, TIMI 1 in 5 cases, and TIMI 2 in 3 cases. The degree of stenosis was 97.9% ± 5.1%.
A 1.4 mm diameter laser catheter was used in 3 cases, a 1.7 mm in 13 cases, and a 1.7 mm following the use of a 1.4 mm catheter in 2 cases. The lesion was crossed with the laser catheter in all the cases. The mean number of laser pulses delivered was 808 ± 384. There was no perforation. Type C dissection developed in only 1 case (6%). Except for this case, distal flow after laser was TIMI 3 in all the cases. The success of laser ablation was thus 94%. Following laser, there was no distal embolization or the need for adjuvant PTCA in any of the cases. Figure 1 shows successful ablation of the blockage in one of the patients.
Stent implantation was performed in all the cases. In a patient who had TIMI 3 flow previously, TIMI 2 flow developed after stenting; TIMI 3 flow was restored with 24 µg intracoronary adenosine. After the ELCA procedure, ST segment resolution of more than 70% was achieved in 14 cases (78%) within the first 90 minutes, and TIMI 3 flow increased from in 0% to in 94% of cases (Table 2
). Mean MLD increased significantly from 0.11 ± 0.23 mm to 1.64 ± 0.28 mm after ELCA and to 3.35 ± 0.41 mm after stent placement. Apart from the single case of type C dissection, there was no perforation, Q or non-Q wave MI, cerebrovascular accident, or death. Glycoprotein IIb/IIIa inhibitor was not used, nor was emergency bypass surgery or PTCA needed. The success of the procedure was thus 94%. The patients were discharged between the 5th and the 7th day after ELCA.
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DISCUSSION
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In the treatment of acute MI, balloon angioplasty is superior to thrombolytic therapy in providing a high rate of TIMI 3 flow in the infarct vessel, in defining the coronary anatomy, and in having a low rate of stroke. However, the presence of thrombus in the lesion increases the rate of complications during and after balloon angioplasty.9 Thrombus dislocation during angioplasty may cause distal embolization and thrombosis.10
Moreover, although TIMI 3 flow was restored by interventional treatment in acute MI, it was found that myocardial metabolism and perfusion were impaired.11,12 Stone and associates13 reported that among the patients in whom TIMI 3 flow was restored by interventional treatment of acute MI, only 29% had grade 3 myocardial perfusion and that 1-year mortality was higher in those who did not have full myocardial perfusion. They found that the strongest predictor of mortality after treatment was the absence of distal flow (TIMI 0/1) and that, in those whose flow was restored to TIMI 3, myocardial blush grade was a better determinant of mortality than TIMI 3 flow. Van’t Hof and co-workers,14,15 using myocardial perfusion grade and ST segment resolution grade to evaluate tissue perfusion, demonstrated a strong correlation between ST segment resolution grade and left ventricular function, enzyme elevation, and mortality. ST segment resolution exceeding 70% was obtained in only 51% of the cases in which TIMI 3 flow was established after PTCA for acute MI.14 Achieving 70% ST segment resolution was taken as an indication of sufficient myocardial perfusion in our study, and this level was reached in 78% of our cases. This high rate might be due to reduced distal embolization and thrombosis induced by ELCA, besides the small number of cases and the shorter interval between onset of symptoms and laser application. We have previously demonstrated that ELCA is more effective than PTCA in ST segment resolution in acute MI.16,17
The presence of thrombus in the lesion has been reported to increase the success of angioplasty treatment using holmium laser,18 while an earlier study using excimer laser found that it increased distal embolization and non-Q wave MI related to the procedure.19 Topaz and associates,4 applying ELCA in 50 patients with acute MI, obtained a success rate of laser ablation of 98% and of the procedure of 100%. There was an 80% reduction in the thrombosed area. There was no death or emergency revascularization. In another study, they reported a success rate of laser ablation of 86% in acute MI and 87% in unstable angina and a success rate of the procedure of 100% in acute MI and 97% in unstable angina.3 There was a 96% reduction in the thrombosed area. Distal embolization or major complications related to the procedure were not observed. Our rates of success and complications are similar to those reported by Topaz’s group.
The discrepancy between the findings of earlier and more recent studies might be related to the introduction of newer laser techniques7,8 and newer catheter designs. Delivery of the laser catheter is very slow (at an average speed of 0.5 mm·sec–1) with the new techniques, which allows maximum laser interaction with the thrombus and more ultraviolet light absorption by the thrombus. In contrast, catheter delivery was faster with older techniques.20 Over-rapid advancement and insufficient laser energy can lead to significantly less thrombus vaporization and to mechanical disruption of the thrombus by the laser catheter. The result may well be thrombus disintegration and distal embolization.
In conclusion, laser coronary thrombolysis allows rapid thrombus removal without inducing systemic lysis and distal embolization, besides debulking the atherosclerotic plaque. These benefits have to be confirmed by randomized studies with larger numbers of cases.
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ABSTRACT
INTRODUCTION
