Morphological predictors of acute complications after percutaneous excimer laser coronary angioplasty. Results of a comprehensive angiographic analysis: importance of the eccentricity index

A novel approach to saline/contrast delivery in excimer laser coronary atherectomy (ELCA) to enhance efficacy: MAXCon ELCA technique

The advent of excimer laser coronary atherectomy (ELCA) nearly four decades ago heralded a novel way to treat complex lesions, both coronary and peripheral, which were previously untraversable and thus untreatable. These complex lesions include heavily calcified lesions, ostial lesions, bifurcation lesions, chronic total occlusions, in-stent restenosis (including stent underexpansion), and degenerative saphenous vein grafts. We discuss the technology of ELCA, its indications, applications, and complications, and suggest the "MAXCon ELCA" technique for better outcomes without increased risk. Lastly, we present a case of MAXCon ELCA effectively treating a complex lesion.

A feasibility study on removing lipid deposition in atherosclerotic plaques with ultrasound-assisted laser ablation

Objective. Atherosclerosis is the buildup of fats, cholesterol, and other substances on the inner walls of arteries. It can affect arteries of heart, brain, arms, legs, pelvis and kidney, resulting in ischemic heart disease, carotid artery disease, peripheral artery disease and chronic kidney disease. Laser-based treatment techniques like laser atherectomy can be used to treat many common atherosclerostic diseases. However, the use of laser-based treatment remains limited due to the high risk of complications and low efficiency in removing atherosclerostic plaques as compared with other treatment methods. In this study, we developed a technology that used high intensity focused ultrasound to assist laser treatment in the removal of the lipid core of atherosclerotic plaques.Approach. The fundamental mechanism to disrupt atherosclerostic plaque was to enhance the mechanical effect of cavitation during laser/ultrasound therapy. To promote cavitation, spatiotemporally synchronized ultrasound bursts of 2% duty cycle at 0.5 MHz and nanosecond laser pulses at 532 nm wavelength were used. Experiments were first performed on pig belly fat samples to titrate ultrasound and laser parameters. Then, experiments were conducted on human plaque samples, where the lipid depositions of the plaques were targeted.Main results. Our results showed that fat tissue could be removed with an ultrasound peak negative pressure (PNP) of 2.45 MPa and a laser radiant exposure as low as 3.2 mJ mm^-2. The lipid depositions on the atherosclerostic plaques were removed with laser radiant exposure of 16 mJ mm^-2in synchronizing with an ultrasound PNP of 5.4 MPa. During all the experiments, laser-only and ultrasound-only control treatments at the same energy levels were not effective in removing the lipid.Significance. The results demonstrated that the addition of ultrasound could effectively reduce the needed laser power for atherosclerotic plaque removal, which will potentially improve treatment safety and efficiency of current laser therapies.

Excimer Laser Coronary Angioplasty: Clinical Applications and Procedural Outcome, in a Large-Volume Tertiary Centre

Excimer-laser coronary angioplasty can be used to modify undilatable and uncrossable lesions in native arteries and in-stent restenosis which are increasingly encountered with the ageing population undergoing coronary intervention. We present our laser experience over a 10-year period in a large cardiac tertiary centre.

METHOD

Retrospective analysis of prospectively collected data on all procedures where laser was used from August 2008 to December 2019. Clinical presentation, demographics, and procedural details were all recorded. Successful procedures were defined as <30% stenosis at the end. Periprocedural and in-hospital complications were recorded and verified. Results are presented as numbers and percentages.

RESULTS

A total of 331 patients were identified with 473 lesions treated with laser and an overall total of 637 lesions. Of the 473 lesions treated, 46 (9.9%) were in-stent restenosis, 146 (30.9%) were chronic total occlusions, and the rest were uncrossable or undilatable lesions. The vast majority of procedures (97.0%) were performed with the 0.9-mm laser catheter. The overall success rate was 81.6% (58-87%) from low- to high-volume user. Complications included dissection 3 (0.6%), no-reflow 3 (0.6%), coronary perforation 13 (2.7%), and tamponade in 1 (0.2%). Only 3 (0.6%) of the perforations were seen after the laser catheter passage, the rest were seen later following balloon preparation or stent insertion.

CONCLUSION

Laser is a valuable tool for treating complex and resistant coronary lesions. Its efficacy and safety are well established and when applied appropriately, it helps to achieve optimal outcomes for our patients.

Atherectomy Devices for the Treatment of Calcified Coronary Lesions

The presence of moderate and severe coronary artery calcification (CAC) is associated with higher rates of angiographic complications during percutaneous coronary intervention (PCI), as well as higher major adverse cardiac events compared with noncalcified lesions. Diabetes mellitus, a risk factor for CAC, is increasing in the United States. Vessel preparation before PCI with atherectomy can facilitate successful stent delivery and expansion that may otherwise not be possible. We review here CAC prevalence, risk factors, and impact on PCI, as well as the currently available coronary atherectomy devices including rotational atherectomy, orbital atherectomy, and laser atherectomy.

New approaches to long lesions

Long coronary lesions, comprising up to 20% of the interventional practice, pose a significant challenge to the interventionalist. Several approaches have been described to treat long coronary lesions with long-term suboptimal outcomes. Atherectomy and laser treatments with or without adjunctive balloon angioplasty have not been shown to be superior to conventional balloon angioplasty alone. Preliminary data with the use of drug-eluting stents in the treatment of long coronary lesions appears to be promising even in small vessels and may eventually become the mainstay treatment of long lesions.

Laser coronary angioplasty: history, present and future

The efficacy of percutaneous transluminal coronary angioplasty (PTCA) is limited by remaining plaque tissue and the development of restenosis. It has been demonstrated that the restenosis rate is low if a large lumen diameter is achieved after coronary intervention. Debulking of coronary stenoses is a concept to increase the luminal diameter after intervention. Laser angioplasty debulks coronary stenoses by ablation of atherosclerotic plaque. Since the first intravascular laser intervention, the technique has been significantly improved by the use of optimized wavelength, the development of flexible optimally spaced multifiber catheters and an additional saline flush technique. These technical advancements allowed a reduction in the incidence of adverse events, such as the number of dissections and perforations, associated with the use of the laser technique. Coronary laser angioplasty is commonly combined with adjunctive balloon angioplasty to optimize the outcome. Laser coronary angioplasty was not followed by a lower restenosis rate compared with plain balloon angioplasty in lesions without stents, however, a randomized comparison of the techniques including the use of the saline flush technique is not available yet. The value of excimer (acronym for excited dimer) laser coronary angioplasty for treatment of in-stent restenosis is still under investigation. So far, nonrandomized single center studies have not suggested a relevant benefit for this technique used for in-stent restenosis. In nonstented lesions there remain niche indications for laser angioplasty such as the treatment of ostial lesions, diffuse lesions or lesions traversable with a guidewire but not with an angioplasty balloon. Laser coronary angioplasty may also be useful after a failed balloon angioplasty and in patients with chronic total occlusions. The potential advantages of combining laser coronary angioplasty with vaporization of thrombus in patients with acute coronary syndromes are currently under evaluation.

Excimer laser facilitated percutaneous coronary intervention of a nondilatable coronary stent

A patient is described in which excimer laser percutaneous coronary intervention is performed inside a suboptimally expanded stent due to nondilatable calcified plaque. The use of excimer laser facilitated full expansion of the stent with a balloon.

Excimer laser spectroscopy: influence of tissue ablation on vessel wall fluorescence

Limited steerability and injury to the normal vessel wall are major drawbacks of laser coronary angioplasty. To overcome these limitations a new generation of laser systems has been developed which allows not only to eliminate the atherosclerotic plaque but to guide the laser beam by analyzing the laser induced tissue fluorescence (= spectroscopy) for the treatment of the atherosclerotic vessel. An excimer laser (MAX 10 LP, 308 nm, Technolas, Munich, Germany) was used with an emitting (phi 1070 microns) and a detecting (phi 130 microns) optical fiber to induce tissue fluorescence which was analyzed quantitatively by a computerized system. Specimens from the descending (thoracic) aorta were obtained from 24 patients (mean age 68.1 years, range 44-92). Tissue fluorescence was induced with ablating (26-30 mJ/mm2) and nonablating (3 mJ/cm2) laser activations. The emitted fluorescence (range 380-575 nm) was normalized to a wavelength of 380 nm; as a measure of tissue fluorescence the intensity ratio at 500 nm divided by 400 nm was calculated in normal (n = 78), mildly atherosclerotic (n = 40), and severely atherosclerotic (n = 48) tissue samples. Repeated laser activations were carried out and tissue fluorescence was checked until the fluorescence spectrum was normalized. All tissue samples were analyzed histologically by a semiquantitative score. Normal tissue samples showed the highest intensity ratios (5.9 +/- 3.4), whereas mildly (2.9 +/- 1.3) and severely atherosclerotic (2.1 +/- 1.0) samples elicited a significantly reduced fluorescence. Repeated tissue ablations were associated with a normalization of fluorescence intensity ratios in the mildly (7.0) as well as in the severely diseased (4.9) vessels. A curvilinear relationship between intensity ratio and the semiquantitative score was observed (r = 0.66) as well as between intensity ratio and intimal wall thickness (r = 0.62). No gender related differences were found but there was an inverse relationship between fluorescence intensity ratio and age (r = 0.56) as well as between intimal thickness and age (r = 0.41). Excimer laser spectroscopy allows reliable detection of atherosclerotic vessel alterations. Fluorescence intensity ratio is inversely proportional to the intimal wall thickness and the severity of the histologic alterations. There is an age dependency of fluorescence intensity ratio which can be explained by an increase in intimal wall thickness. Successful tissue ablation can be obtained by laser angioplasty and allows determination of the optimal point where complete tissue ablation is achieved by laser activation. Thus, excimer laser spectroscopy is an effective method for selective tissue ablation by laser angioplasty.

Treatment of in-stent coronary restenosis by excimer laser angioplasty

We evaluated the efficacy and safety of excimer laser angioplasty (ELCA) with adjunctive balloon angioplasty in patients with restenotic or occluded coronary stents. ELCA was performed in 70 patients (60 +/- 9 years), who had previously been treated with Micro Stents (n = 65), Palmaz-Schatz (n = 38), Wiktor, NIR, Freedom, and Multi-Link stents (n = 1 each). Restenosis (> or =50% diameter stenosis) was documented in 90 stents, another 17 stents were occluded. Laser energy was delivered to the lesions with catheters 1.4, 1.7 (eccentric), and 2.0 mm in diameter. Procedural success was controlled by intravascular ultrasound in a subgroup. Laser catheters crossed all restenotic or occluded stents and decreased diameter stenosis from 80 +/- 13% to 44 +/- 11% (p <0.001). Adjunctive balloon angioplasty further reduced diameter stenosis to 13 +/- 13% (p <0.001). In 13 patients with 21 stents, serial intravascular ultrasound imaging revealed a reduction of plaque area within the stent by 34 +/- 22% (from 4.2 +/- 1.8 mm2 to 2.7 +/- 1.1 mm2) after ELCA and a reduction by 65 +/- 16% (to 1.5 +/- 0.7 mm2) after balloon angioplasty (p <0.01). There were 4 patients with an increase of creatine kinase levels, 8 patients with major dissections (in 7 patients they were related to adjunctive balloon angioplasty), 1 patient with distal embolization, 2 with minor perforations, and 1 patient with stent dislocation. Reintervention during hospitalization was necessary in 3 patients. ELCA is an efficient and safe technique to debulk tissue in restenotic lesions and total occlusions within stents. The incidence of procedure related complications was low.

[Laser angioplasty and recanalization]

Percutaneous transluminal coronary balloon angioplasty (PTCA) still is the most frequently applied interventional technique for treatment of coronary artery disease. Plastic deformation of the obstructive plaque with creation of splits, intimal tears and dissections is the main mechanism of PTCA for lumen widening. As a result, acute complications due to flow limiting dissections and acute vessel closure can unpredictably occur resulting in myocardial infarction, urgent bypass surgery and death. Furthermore, long-term success of PTCA is limited by restenosis. In order to overcome these limitations of PTCA, alternative interventional techniques were developed, which instead of deforming the obstructive plaque ablate this tissue. These techniques include high and low speed rotational angioplasty, directional atherectomy, the transluminal extraction catheter, ultrasound angioplasty and laser (Light Amplification by Stimulated Emission of Radiation) angioplasty. 308 nm XeCl excimer laser angioplasty today is the laser technique of choice for clinical application. This pulsed laser requires direct contact to the obstructive plaque. It creates fast (< 200 microseconds) expanding gas bubbles which induce plaque ablation. Main indications for 308 nm XeCl excimer laser angioplasty are diffuse and long coronary lesions and total coronary occlusions. Despite promising initial results this technique showed no better acute and long-term results in comparison to PTCA for the treatment of these types of lesions ("Amsterdam-Rotterdam" Study, "Excimer Rotational Balloon Angioplasty Comparison" Study). As a result, this interventional technique was rarely applied for patient treatment. More recently, the concept of plaque ablation by 308 nm XeCl excimer laser angioplasty was renewed for the treatment of in-stent restenosis. This indication is being investigated in the "Laser Angioplasty of Restenosed Stents" trial. First results document the practicability and safety of this approach. Long-term results are awaited. With ongoing miniaturization, laser guidewires were developed for the recanalization of chronic total occlusions. The randomized multicenter "Total Occlusion Trial with Angioplasty assisted by Laser guidewire "Study documented a success rate of laser wire recanalization in up to 66% in contrast to 47.5% for mechanical wires only. Long-term results are still awaited. Technical and procedural progress including saline flush during laser application, homogeneous light distribution and the concept of smooth laser ablation is pushed foreward to make excimer laser angioplasty safer, more predictable and more effective.

Frequency and predictors of major in-hospital ischemic complications after planned and unplanned new-device angioplasty from the New Approaches to Coronary Intervention (NACI) registry

The purpose of this study was to determine the frequency and predictors of major in-hospital ischemic complications after planned and unplanned procedures with new angioplasty devices from the New Approaches to Coronary Intervention (NACI) registry. The NACI registry is a multicenter, voluntary reporting of consecutive patients undergoing new-device angioplasty procedures using atherectomy catheters, stents, or lasers. This registry affords the opportunity to evaluate the performance of new angioplasty devices during elective and urgent circumstances. The study population consisted of 3,340 patients with 3,733 lesions (2,921 in native coronary arteries and 812 in saphenous vein grafts [SVGs], who were treated with new devices over a 3.5-year period and had their angiograms analyzed independently at a central angiographic core laboratory. Their in-hospital course and multivariate predictors of the complications in planned and unplanned procedures, further divided into native and SVG lesions, were evaluated. In 82.2% of native coronary artery lesions and 96.9% of SVG lesions, the procedure with a device had been planned due to unfavorable lesion characteristics for PTCA. In the remaining lesions, device use was unplanned, and was performed mainly to treat a suboptimal result (59-80.4%) after percutaneous transluminal coronary angioplasty (PTCA), and less frequently after important complications of PTCA including abrupt closure and PTCA failure. In native artery cohort, major in-hospital ischemic complications (death, Q-wave myocardial infarction [MI], or emergency coronary artery bypass surgery) occurred in 2.7% of the planned and 9.9% of the unplanned procedures (p < 0.001), whereas in SVG such complications occurred in 3.6% of the planned and 8.7% of unplanned procedures (p = 0.21). Multivariate analysis revealed several predictors of major ischemic complications from planned native coronary artery device use: post-MI angina (odds ratio = 2.83); severe concomitant noncardiac disease (odds ratio = 2.5); multivessel disease (odds ratio = 1.75); and de novo lesions (odds ratio = 2.3). Multivariate predictors of major complications in unplanned native coronary artery procedures included high surgical risk (odds ratio = 3.08), and tortuous lesion (odds ratio = 2.41). In SVG lesions, the independent predictors of major complications for planned procedures included age (odds ratio = 1.09), high surgical risk (odds ratio = 4.34), and thrombus (odds ratio = 2.62). In native and SVG lesions, rates of major complications of planned procedures was acceptable (2.7-3.67%), but unplanned use of a new device was associated with a significantly higher rate of in-hospital complications (approximately 9%). Multivariate predictors for major ischemic complications included both clinical and lesion characteristics, and differed for native versus SVG lesions, as well as for planned versus unplanned procedures.

Myocardial infarction as a complication of new interventional devices

Percutaneous transluminal coronary balloon angioplasty has been associated with acute myocardial infarction (MI) as a complication of the procedure. Abrupt closure, distal coronary embolization, intimal dissection, coronary spasm, and acute thrombosis are the principal etiologies. New interventional devices (stent, laser, and atherectomy catheters) have been introduced as alternatives or adjuncts to balloon angioplasty. With use of the New Approaches to Coronary Intervention Registry, the incidence, predictors, and outcome of MI as a complication of using these devices as the primary mode of intervention were studied. There were 3,265 patients from 39 participating centers in the cohort treated with new devices. MI was reported as an in-hospital complication of using new devices in 154 patients (4.7%), including Q-wave MI in 36 patients (1.1%), and non-Q-wave MI in 119 patients (3.6%). MI rates were not significantly different among all patients with devices in the cohort treated with atherectomy (directional, extractional, rotational), laser (AIS, Spectranetics) or the Palmaz-Schatz stent. Multivariate logistic regression showed that post-procedure MI was associated with multivessel disease, high surgical risk, postinfarction angina, and presence of a thrombus prior to the procedure. Prior percutaneous transluminal coronary angioplasty was inversely related to the incidence of MI. When a specific cause of MI could be detected, the main etiologies were: coronary embolus 16.9%, and abrupt closure 27.3%. Other major in-hospital complications were higher in the MI group than the non-MI group: death 7.8% versus 0.8% (p <0.001), and bypass surgery 13.6% versus 1.7% (p <0.001). At 1 year, mortality rates remain higher at 12.9% in the MI group versus 4.9% in the non-MI group (p <0.01). Despite different indications for the use of new devices, they were not predictors for MI with the exception of the rotablator. The incidence of MI (1.1% Q-wave, 3.6% non-Q-wave) was comparable to previously reported rates for balloon angioplasty. The occurrence of MI is associated with an increase in other in-hospital complications and a doubling of 1-year mortality.

Limitations of angiography in the assessment of plaque distribution in coronary artery disease: a systematic study of target lesion eccentricity in 1446 lesions

BACKGROUND

Plaque distribution (eccentricity) may be a determinant of the success of transcatheter therapy, and certain devices may be better suited to treating severely eccentric lesions than others. However, no study has compared methods for assessing plaque distribution or systematically studied the validity of the angiographic assessment of plaque distribution.

METHODS AND RESULTS

We studied 1446 native vessel target lesions in 1349 patients by intravascular ultrasound and coronary angiography. Angiographic and intravascular ultrasound criteria for lesion eccentricity were compared. Angiography showed that 795 of 1446 (55.0%) of target lesions were eccentric. When intravascular ultrasound was used, only 219 lesions (15.1%) had an arc of normal arterial wall within the lesion (equivalent to the pathological definition of lesion eccentricity). When an eccentricity index of >/= 3.0 was used, intravascular ultrasound classified 659 lesions (45.6%) as eccentric. The concordance rates of classification were only 47.7% (versus lesions containing an arc of normal arterial wall) and 53.8% (versus lesions with an ultrasound eccentricity index of >/= 3.0). More eccentric lesions had larger lumen cross-sectional areas, smaller plaque plus media and external elastic membrane cross-sectional areas, and smaller arcs of calcium, suggesting that they may represent less advanced atherosclerotic disease.

CONCLUSIONS

There was significant discordance between angiography and ultrasound in assessing plaque distribution. Angiography appeared to detect lesion eccentricity more often than intravascular ultrasound. Furthermore, markedly eccentric lesions, in which there is an arc of normal vessel wall, were uncommon.

The changing profile of patient selection, procedural techniques, and outcomes in excimer laser coronary angioplasty. Participating Investigators of the Percutaneous Excimer Laser Coronary Angioplasty Registry

During the course of development of excimer laser angioplasty, several changes in patient selection and technique have occurred. It is uncertain, however, whether these changes have been associated with improved procedural outcome. In this study, multivariable regression methods were used to identify the factors responsible for clinical success, major complications, and vessel perforation in 2,041 consecutive patients treated with excimer laser coronary angioplasty. The overall rates of clinical success were 89%, major complications 7.5%, and vessel perforation 2.1%. Clinical success was 86% in patients treated with prototype catheters, 89% with flexible catheters, 92% with extremely flexible catheters, and 95% in patients treated with directional eccentric catheters (P < 0.001). By multivariable analysis, clinical success increased with each subsequent catheter design (odds ratio [OR] = 1.4 per iteration [95% confidence interval 1.2, 1.6]), and with improved lesion selection. Major complications were reduced when operators had performed more than 25 cases (rate = 6.5%, OR = 0.7 [0.5, 0.9]), and the incidence of vessel perforation was decreased when the size of the target vessel was > 1.0 mm larger than the diameter of the laser catheter (rate = 1.1%, OR = 0.3 [0.2, 0.5]). In conclusion, during the course of clinical investigation with excimer laser angioplasty, procedural outcome has improved. These results emphasize the importance of careful patient selection and procedural technique to enhance the success of excimer laser angioplasty.

Usefulness of a prototype directional catheter for excimer laser coronary angioplasty in narrowings unfavorable for conventional excimer or balloon angioplasty

We report clinical and angiographic results in 53 patients with 57 significant coronary or saphenous vein graft narrowings treated with directional excimer laser angioplasty. The target vessels were the left main (1%), anterior descending (32%), circumflex (19%), right coronary artery (39%), and vein grafts (9%). Lesions were morphologic class B1 (18%), B2 (79%), or C (3%), with 40 de novo and 17 restenotic lesions. Adjunctive balloon angioplasty was used in 53 lesions (93%). Mean pre- and postprocedural minimal lumen diameters were 0.6 +/- 0.3 and 1.9 +/- 0.7 mm (p < 0.001), corresponding to a mean diameter stenosis of 72 +/- 20% and 27 +/- 16%. Procedural success rate was 91%. Cumulative risk of death, Q-wave myocardial infarction, or emergency bypass operation was 9% (5 patients). Of patients who had a successful laser procedure, 28 (60%) with 30 lesions underwent angiographic follow-up at 6 +/- 3 months after the procedure. Restenosis rates (> 50% diameter restenosis or acute gain loss) were 37% and 23%, respectively. Four patients underwent bypass, 3 angioplasty, and 1 patient died from cancer. This study demonstrates the feasibility of directional application of laser energy to selected unfavorable narrowings for conventional excimer laser or balloon angioplasty. Further evaluation of this device using the now standard saline infusion technique is necessary to establish its ultimate role as a primary interventional device.

Predictors of restenosis after excimer laser coronary angioplasty

One hundred twenty-five lesions successfully treated with excimer laser coronary angioplasty at 3 centers were analyzed in a central core laboratory using detailed quantitative angiographic analysis. Sixty-seven narrowings had restenosis (> or = 50% diameter stenosis at restudy). Correlates of restenosis were as follows: baseline diameter stenosis was 79% in the restenosis group versus 71% in the group without restenosis (p = 0.0002), baseline minimal diameter stenosis was 0.55 mm in the restenosis group versus 0.72 mm in the group without restenosis (p = 0.006), final diameter stenosis was 40% in the restenosis group versus 32% in the group without restenosis (p = 0.002), lesion length > or = 7 mm was present in 43% of the restenosis group versus 21% in the group without restenosis (p = 0.009), and Thrombolysis in Myocardial Infarction trial flow 0 to 2 was 33% in the restenosis group versus 15% in the group without restenosis (p = 0.025). The strongest multivariate correlate of restenosis was the baseline diameter stenosis (p = 0.003). Whereas most predictors were not controllable, achieving a low residual diameter stenosis that is operator-dependent can favorably influence the restenosis rate.

Coronary perforation after excimer laser coronary angioplasty: the Excimer Laser Coronary Angioplasty Registry experience

OBJECTIVES

This study assessed the frequency of perforation with excimer coronary angioplasty.

BACKGROUND

Coronary artery perforation after conventional percutaneous transluminal coronary angioplasty is extremely rare. Because laser coronary angioplasty involves actual tissue ablation, it has an increased potential for perforation.

METHODS

All patients in the Excimer Laser Coronary Angioplasty Registry were included in this prospective study. Those who had a perforation related to the procedure were compared with those who did not have this complication.

RESULTS

Of 2,759 consecutive patients in the Excimer Laser Coronary Angioplasty Registry, 36 (1.3%) had perforation. In these patients, the left anterior descending coronary artery was the most frequently treated vessel (53%). There were no differences in fiber sizes between patients with and those without perforation. Among the patients with perforation, 36.1% required coronary artery bypass surgery, 16.7% experienced an infarction and 5.6% had a fatal outcome. Among the patients without perforation, the rates were 3.1%, 3.8% and 0.6%, respectively. However, 41.7% of the patients with documented coronary artery perforation did not need coronary artery bypass surgery or experience myocardial infarction or death. No angiographic characteristics distinguished lesions with from those without perforation. The frequency of coronary artery perforation declined over time with increasing operator experience, from 1.6% in the first 1,888 patients to only 0.4% in the last 1,000 patients (p = 0.002).

CONCLUSIONS

With increasing operator experience, the rate of perforation with excimer laser coronary angioplasty has decreased. When perforation occurs, subsequent event rates increase.

Cardiovascular applications of laser technology

Laser technology has been evaluated for the treatment of coronary artery disease, ventricular and supraventricular arrythmias, hypertrophic cardiomyopathy, and congenital heart disease. Developments in laser angioplasty, laser thrombolysis, transmyocardial laser revascularization, photochemotherapy, laser treatment of arrhythmias and/or laser diagnostics are directed at improving upon conventional non-laser approaches, and providing new therapeutic and diagnostic options. This review will summarize the current status of the multiple applications of laser technology for cardiovascular diagnosis and therapy.

Coronary laser angioplasty

With the widespread growth of percutaneous transluminal coronary angioplasty (PTCA), the realization of limitations of balloon angioplasty stimulated the development of alternative revascularization approaches such as laser angioplasty. PTCA is best suited for the treatment of discrete atherosclerotic stenoses, with lower success rates and more difficult application in patients with diffuse atherosclerotic disease or total occlusions [1-3]. Moreover, despite an initially high primary success rate, coronary angioplasty is still plagued by a restenosis rate as high as 57% [4]. The potential advantages of laser angioplasty address the limitations of PTCA. In contrast to balloon angioplasty where the plaque material is compressed or displaced, laser angioplasty ablates the plaque material [5]. This bulk removal of plaque material could improve acute procedural success rates, decrease complication rates, treat "untreatable" lesions, and decrease restenosis rates. Because laser energy can vaporize atherosclerotic plaque, there may be no requirement for a preexisting channel, and therefore laser angioplasty may have a high success rate for the treatment of coronary occlusions. In its best embodiment, laser angioplasty offers the potential for passing a fiberoptic catheter through the entire length of the coronary circulation to vaporize all atherosclerotic plaque along the arterial wall. This applicability for the treatment of diffuse atherosclerotic disease would offer treatment opportunities currently unavailable with conventional bypass surgery or angioplasty.