The state of the excimer laser for coronary intervention in the drug-eluting stent era




Abstract


Objectives


This study aims to determine how excimer laser coronary atherectomy (ELCA) performs in the drug-eluting stent (DES) era.


Background


For more than 20 years, ELCA has been used for coronary intervention. With developments in the coronary intervention field, the role of ELCA is in question.


Methods


The study includes 119 patients with 124 lesions who underwent percutaneous coronary intervention (PCI) with ELCA in our institution from January 2004 to May 2011.


Results


The main indications for ELCA use were saphenous vein graft (SVG) (45 lesions), acute myocardial infarction (AMI) (7 lesions), chronic total occlusion (CTO) (32 lesions), in-stent restenosis (ISR) (15 lesions), and calcified de-novo lesions (25 lesions). High success rates were recorded for the SVG, AMI, CTO, ISR, and calcified lesion indications (91.1%, 85.7%, 93.8%, 86.7%, and 80%; respectively). ELCA related complications were reported in 10 patients (8%); four dissections, three no-reflow phenomena, two perforations, and one thrombus formation.


Conclusion


ELCA is an alternative solution with acceptable performance in the treatment of complex coronary lesions not ideally suitable for balloon angioplasty.



Introduction


Excimer laser coronary atherectomy (ELCA) was introduced two decades ago for the treatment of complex coronary artery interventions. The US Food and Drug Administration (FDA) approved ELCA for marketing for the following indications: Debulking of saphenous vein grafts (SVG); ostial lesions; eccentric lesions; long lesions (> 20 mm); total occlusions crossable by a guide wire; moderately calcified lesions; balloon refractory lesions; and in-stent restenosis (ISR).


When tested against balloon angioplasty, stenting, and other atherectomy devices, however, ELCA failed to show superiority for efficacy and safety . Subsequently, especially after the introduction of drug-eluting stents (DESs), the use of ELCA was limited to a few centers and to select patient and lesion cohorts. Since its introduction, several modifications in ELCA technology have been made to further improve procedure outcomes and safety. Namely, a xenon–chlorine (excimer) pulsed laser catheter (X80; Spectranetics, Colorado Springs, CO) capable of delivering higher energy density with lower heat production (smaller area of ablation), has improved results beyond those encountered with first-generation devices . Further, saline infusion for blood and dye clearance prevents vapor bubble formation and its accompanying acousto-mechanical trauma to the vessel wall, leading to a decrease in coronary dissection rate . This report details the experience and outcomes after ELCA for various coronary indications in the DES era.





Methods



Study population and data collection


The study includes all patients who underwent percutaneous coronary intervention (PCI) with ELCA at our institution from January 2004 to May 2011. Clinical and demographic data, as well as clinical events during hospitalization, were collected from hospital charts, reviewed by qualified personnel, and entered prospectively into a general PCI database. The analysis was conducted in accordance with our local Institutional Review Board regulations.



Study protocol


PCI was performed based on the standard clinical guidelines. ELCA catheter size and pharmacological therapy decisions were made by the operator. All patients received aspirin 325 mg before the procedure and a clopidogrel loading dose of 300–600 mg during or just after the procedure. Anticoagulation during the PCI included bivalirudin (0.75 mg/kg bolus followed by a 1.75 mg/kg/h infusion) or non fractionated heparin (40 U/kg bolus with an additional dose to achieve an active clotting time of 250–300 s). At discharge, patients were recommended to take dual antiplatelet therapy (DAPT) for 12 months and aspirin indefinitely.



ELCA procedure


Operators utilized the Spectranetics CVX-300 (Spectranetics, Colorado Springs, CO) ELCA system composed of an excimer laser generator [CVX 300] ( Fig. 1 ) and pulsed xenon–chlorine laser catheters capable of delivering excimer energy (wave length: 308 nm, pulse length: 185 ns) from 30 to 80 mJ/mm 2 (fluencies) at pulse repetition rates from 25 to 80 Hz. ( Fig. 2 ) To date, 0.9-, 1.4-, 1.7- and 2-mm catheters are available. The catheter is prepared by flushing the central guide wire lumen and connecting the proximal end to the laser console. Catheter calibration is performed and the desired energy level is set. The catheter is then passed over the guide wire just proximal to the lesion. The flush-and-bathe technique for blood and dye clearance by saline infusion reduces the extent of collateral damage during angioplasty, which is why it’s mandatory before each lasing train . Each lasing cycle characterized by 10 s of active firing and 5 s of silence, with a slow advancement rate of 0.2 mm/s, yields maximal plaque ablation. If the advancement through the lesion cannot be maintained at a steady pace, increasing the fluency or repetition should be tried. Forceful pushing should be avoided due to an increased risk of vessel perforation . The procedure is then finalized by withdrawing the catheter according to standard practice.




Fig. 1


Spectranetics CVX-300 excimer laser generator.



Fig. 2


Spectranetics CVX-300 catheter overview.



Definitions


ELCA technical success was defined as the laser catheter crossing the entire length of the stenotic lesion determined by angiographic evidence of the catheter tip in the artery distal to the stenosis. Angiographic success was defined as < 50% residual stenosis after ELCA and adjunctive therapy. Clinical success was defined as procedural success with absence of major clinical events at hospital discharge. Clinical events analyzed included death, Q-wave myocardial infarction (QWMI) and non-Q-wave myocardial infarction (NQWMI); QWMI and NQWMI were defined as an increment of CK-MB twice the maximum normal values, associated in the first case to the development of a new Q wave, deeper than ≥ 1 mm, in ≥ 2 contiguous leads. Antegrade flow was assessed by the Thrombolysis In Myocardial Infarction (TIMI) scale . Lesion morphology was characterized by the modified American College of Cardiology/American Heart Association (ACC/AHA) score .


ELCA complications included dissection type C or worse according to the National Heart, Lung and Blood Institute classification , coronary spasm, thrombus formation, no reflow, embolization, perforation, loss of the major side branch (> 2 mm in diameter), and acute closure. Spasm was defined as transient reduction in blood flow with vessel caliber narrowing relieved either spontaneously or by nitroglycerine. Thrombus formation was defined as the new appearance of an intraluminal filling defect or haziness refractory to intracoronary nitroglycerine. The no-reflow phenomenon is defined as inadequate myocardial perfusion through a given segment of the coronary circulation without angiographic evidence of mechanical vessel obstruction . Perforation was defined as the demonstration of a persistent extravascular collection of contrast medium beyond the vessel wall. Finally, acute closure was defined as sustained TIMI 0 to 1 flow grade caused by obstruction of the target lesion.



Statistical analysis


Data analyses were performed using SAS 9.1 (SAS Institute, Cary, NC). Continuous variables are presented as mean ± SD and categorical variables as proportion and percentage. Among the five study groups, differences in continuous variables were compared by analysis of variance. Categorical variables were compared using the chi-square test or Fisher’s exact test as indicated. Paired tests were analyzed by paired Student’s t test. Significance was set at a p value < 0.05.





Methods



Study population and data collection


The study includes all patients who underwent percutaneous coronary intervention (PCI) with ELCA at our institution from January 2004 to May 2011. Clinical and demographic data, as well as clinical events during hospitalization, were collected from hospital charts, reviewed by qualified personnel, and entered prospectively into a general PCI database. The analysis was conducted in accordance with our local Institutional Review Board regulations.



Study protocol


PCI was performed based on the standard clinical guidelines. ELCA catheter size and pharmacological therapy decisions were made by the operator. All patients received aspirin 325 mg before the procedure and a clopidogrel loading dose of 300–600 mg during or just after the procedure. Anticoagulation during the PCI included bivalirudin (0.75 mg/kg bolus followed by a 1.75 mg/kg/h infusion) or non fractionated heparin (40 U/kg bolus with an additional dose to achieve an active clotting time of 250–300 s). At discharge, patients were recommended to take dual antiplatelet therapy (DAPT) for 12 months and aspirin indefinitely.



ELCA procedure


Operators utilized the Spectranetics CVX-300 (Spectranetics, Colorado Springs, CO) ELCA system composed of an excimer laser generator [CVX 300] ( Fig. 1 ) and pulsed xenon–chlorine laser catheters capable of delivering excimer energy (wave length: 308 nm, pulse length: 185 ns) from 30 to 80 mJ/mm 2 (fluencies) at pulse repetition rates from 25 to 80 Hz. ( Fig. 2 ) To date, 0.9-, 1.4-, 1.7- and 2-mm catheters are available. The catheter is prepared by flushing the central guide wire lumen and connecting the proximal end to the laser console. Catheter calibration is performed and the desired energy level is set. The catheter is then passed over the guide wire just proximal to the lesion. The flush-and-bathe technique for blood and dye clearance by saline infusion reduces the extent of collateral damage during angioplasty, which is why it’s mandatory before each lasing train . Each lasing cycle characterized by 10 s of active firing and 5 s of silence, with a slow advancement rate of 0.2 mm/s, yields maximal plaque ablation. If the advancement through the lesion cannot be maintained at a steady pace, increasing the fluency or repetition should be tried. Forceful pushing should be avoided due to an increased risk of vessel perforation . The procedure is then finalized by withdrawing the catheter according to standard practice.




Fig. 1


Spectranetics CVX-300 excimer laser generator.



Fig. 2


Spectranetics CVX-300 catheter overview.



Definitions


ELCA technical success was defined as the laser catheter crossing the entire length of the stenotic lesion determined by angiographic evidence of the catheter tip in the artery distal to the stenosis. Angiographic success was defined as < 50% residual stenosis after ELCA and adjunctive therapy. Clinical success was defined as procedural success with absence of major clinical events at hospital discharge. Clinical events analyzed included death, Q-wave myocardial infarction (QWMI) and non-Q-wave myocardial infarction (NQWMI); QWMI and NQWMI were defined as an increment of CK-MB twice the maximum normal values, associated in the first case to the development of a new Q wave, deeper than ≥ 1 mm, in ≥ 2 contiguous leads. Antegrade flow was assessed by the Thrombolysis In Myocardial Infarction (TIMI) scale . Lesion morphology was characterized by the modified American College of Cardiology/American Heart Association (ACC/AHA) score .


ELCA complications included dissection type C or worse according to the National Heart, Lung and Blood Institute classification , coronary spasm, thrombus formation, no reflow, embolization, perforation, loss of the major side branch (> 2 mm in diameter), and acute closure. Spasm was defined as transient reduction in blood flow with vessel caliber narrowing relieved either spontaneously or by nitroglycerine. Thrombus formation was defined as the new appearance of an intraluminal filling defect or haziness refractory to intracoronary nitroglycerine. The no-reflow phenomenon is defined as inadequate myocardial perfusion through a given segment of the coronary circulation without angiographic evidence of mechanical vessel obstruction . Perforation was defined as the demonstration of a persistent extravascular collection of contrast medium beyond the vessel wall. Finally, acute closure was defined as sustained TIMI 0 to 1 flow grade caused by obstruction of the target lesion.



Statistical analysis


Data analyses were performed using SAS 9.1 (SAS Institute, Cary, NC). Continuous variables are presented as mean ± SD and categorical variables as proportion and percentage. Among the five study groups, differences in continuous variables were compared by analysis of variance. Categorical variables were compared using the chi-square test or Fisher’s exact test as indicated. Paired tests were analyzed by paired Student’s t test. Significance was set at a p value < 0.05.





Results


We report on a series of 119 patients with 124 lesions treated by ELCA. Of these, 40 patients (33.6%) underwent intervention to the SVG; 7 patients (5.9%) were treated for AMI; 32 patients (26.9%) for CTO; 15 patients (12.6%) for ISR; and 25 patients (21%) for severe calcification as the primary indication ( Fig. 3 ).




Fig. 3


Different uses for laser in the drug-eluting stent era.


The cohort’s baseline characteristics are displayed in Table 1 . Table 2 shows procedural data. There was no difference regarding procedure length. Smaller laser catheters of 0.9 and 1.4 mm in diameter were used more frequently than those with diameters of 1.7 and 2.0 mm. Seventy-six percent of lesions in the calcification group were type C lesions according to ACC/AHA classification. The balloon non-crossable lesions were observed more frequently in the CTO- (71.9%) and calcification groups (56%).



Table 1

Baseline characteristics.























































































Saphenous vein graft Acute myocardial infarction Chronic total occlusion In-stent restenosis Calcified lesion
(n = 45) (n = 7) (n = 32) (n = 15) (n = 25)
Age 72.3 ± 10.2 65.6 ± 15.6 62.0 ± 11.6 62.5 ± 10 70.2 ± 13.7
Men 31 (77.5%) 6 (85.7%) 23 (71.9%) 10 (66.7%) 15 (60%)
Hypertension 39 (97.5%) 4.0 (66.7%) 29 (90.6%) 14 (93.3%) 22 (88%)
Diabetes 21 (53.8%) 2.0 (33.3%) 15 (46.9%) 9.0 (60%) 9.0 (36%)
Hyperlipidemia 38 (95%) 6.0 (100%) 31 (96.9%) 15 (100%) 24 (96%)
Peripheral vascular disease 17 (43.6%) 0 9.0 (28.1%) 4.0 (30.8%) 2.0 (8.0%)
Renal failure 2.0 (5.0%) 0 2.0 (6.3%) 1.0 (6.7%) 3.0 (12%)
Prior percutaneous coronary intervention 17 (47.2%) 3.0 (42.9%) 9.0 (31%) 11 (100%) 11 (47.8%)
Prior coronary artery bypass graft 40 (100%) 2.0 (28.6%) 5.0 (15.6%) 6.0 (40%) 7 (29.2%)
Ejection fraction 43% ± 15% 42% ± 8.0% 45% ± 17% 42% ± 15% 53% ± 11%

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Nov 14, 2017 | Posted by in CARDIOLOGY | Comments Off on The state of the excimer laser for coronary intervention in the drug-eluting stent era

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