Diffuse embolization following percutaneous transluminal coronary angioplasty of occluded vein grafts: the blush phenomenon

Excimer laser thrombus elimination for prevention of distal embolization and no-reflow in patients with acute ST elevation myocardial infarction

BACKGROUND

Results for standard revascularization therapies in acute myocardial infarction (AMI) have been limited in part by distal embolization, a process which might be reduced by the application of ultraviolet laser light. The aim was to assess feasibility and safety of excimer laser coronary angioplasty (ELCA) in a randomized study in AMI.

METHODS

Twenty-seven consecutive patients with ST-segment elevation AMI (aged 57.8+/-9.2 years) were randomized either to balloon angioplasty and stent implantation alone (n=13) or adjunct ELCA (n=14). Quantitative coronary angiography was analyzed by an independent core laboratory.

RESULTS

ELCA was feasible and safe in all cases. No procedure-associated complications were observed. Similar results were found for main parameters in laser (L) and control (C) patients: diameter stenosis decreased from 94.3+/-9.6 to 20.7+/-10.3% (L) and from 82.7+/-16.8 to 18.9+/-5.5% (C) (p=ns; L vs. C). TIMI flow increased from 0.7+/-1.2 to 2.8+/-0.4 and from 1.7+/-1.5 to 3.0+/-0 (p=ns; L vs. C), respectively. The post-procedural myocardial blush score did not differ between the groups (2.1+/-1.3 and 2.7+/-1.0; p=ns; L vs. C) and the final corrected TIMI frame count (cTFC) was also similar in both groups (23+/-7 and 22+/-4; p=ns; L vs. C), but the cTFC gain was higher in the laser group (53+/-14% and 35+/-20%; p<0.05; L vs. C).

CONCLUSIONS

Laser angioplasty is feasible and safe for the treatment of patients with ST elevation AMI. Procedural results were at least on par with conventional treatment. Further randomized controlled trials are needed to assess the benefit of laser angioplasty in AMI.

Outcome of acute myocardial infarction in patients with prior coronary artery bypass grafting treated with combination reduced fibrinolytic therapy and abciximab

ST-segment elevation acute myocardial infarction (AMI) in patients who have undergone previous coronary artery bypass grafting (CABG) is associated with low reperfusion rates and poor outcome after fibrinolytic therapy. The efficacy of a combination strategy (reduced fibrinolytic plus platelet glycoprotein IIb/IIIa agent) in this setting is unknown. In the Global Use of Streptokinase and TPA for Occluded coronary arteries V (GUSTO V) trial, 553 patients with a history of CABG were treated with standard-dose reteplase (n = 273), or half-dose reteplase and full-dose abciximab (n = 280) in the first 6 hours of evolving ST-segment elevation MI. Mortality at 30 days was significantly higher in patients who underwent prior CABG compared with patients with no prior CABG (odds ratio [OR] 1.64, 95% confidence interval [CI] 1.21 to 2.24, p = 0.001). In patients who underwent prior CABG, mortality at 7 days was reduced 15% with combination therapy compared with reteplase alone, which was not statistically significant (OR 0.85, 95% CI 0.40 to 1.81, p = 0.66). Patients who underwent prior CABG treated with the combination therapy had fewer episodes of recurrent ischemia (OR 0.60, 95% CI 0.37 to 0.96, p = 0.02), high degree atrioventricular block (OR 0.17, 95% CI 0.02 to 0.82, p = 0.01), and ventricular tachycardia (OR 0.29, 95% CI 0.07 to 0.96, p = 0.04). There was a trend toward reduced urgent revascularization (OR 0.61, 95% CI 0.36 to 1.03, p = 0.06) but no significant difference in reinfarction (OR 0.61, 95% CI 0.31 to 1.52, p = 0.40). In the GUSTO V trial, patients who underwent prior CABG had significantly higher event rates compared with patients without CABG. As in the overall trial, combination therapy in patients who underwent prior CABG led to a consistent reduction in key secondary complications of AMI, including recurrent ischemia and a trend toward reduced urgent revascularization.

Procedural results and intermediate clinical outcomes after multiple saphenous vein graft stenting

OBJECTIVES

We evaluated the early and mid-term (18-month) clinical events in a consecutive series of patients undergoing a nonstaged multiple saphenous vein grafting (SVG) intervention with stents as compared with a single SVG stent procedure.

BACKGROUND

Saphenous vein graft angioplasty has been limited by high rates of distal embolization, myocardial infarction, restenosis and late mortality. It is unknown whether stenting of multiple, different SVGs at the same setting is associated with higher risk.

METHODS

We evaluated in-hospital and mid-term clinical outcomes (death, Q wave myocardial infarction [MI] and repeat revascularization rates up to 18 months) in 70 consecutive patients treated with coronary stents in 2 (93% of patients) or 3 SVGs, as compared with 649 patients undergoing stenting of a single SVG between January 1, 1994 and December 31, 1997.

RESULTS

Overall procedural success was obtained in 97% of patients with 2 or 3 SVGs and 97% of patients with a single SVG (p = 0.94). Procedural complications were also similar (2.8% for multiple SVGs vs. 2.7% for a single SVG, p = 0.94). There was a higher prevalence of periprocedural non-Q wave MI (28% vs. 16%, p = 0.009) in the multiple SVG group. During follow-up (18 months), target lesion revascularization was 11% in multiple SVG and 15% in single SVG interventions (p = 0.19), and repeat revascularization (calculated per treated patient) was also similar for both groups (19% vs. 18%, p = 0.94). There was no difference in death (5.6% vs. 5.3%, p = 0.92) and Q wave MI rate (4.3% vs. 2.9%, p = 0.55) after the multiple SVG intervention. Overall cardiac event-free survival was similar for both groups (62% vs. 60%, p = 0.75). The study was powered to detect a clinically meaningful difference of 10% in mortality; smaller differences could not be evaluated on the basis of this sample size.

CONCLUSIONS

Simultaneous stenting of multiple SVGs in carefully selected patients has similar in-hospital procedural success and major complications rates, as well as mid-term (18-month) clinical outcomes, as compared with single SVG stenting. Thus, multiple SVG interventions using stents may be a viable revascularization strategy for carefully selected patients and suitable lesions in multiple SVG disease.

Sustained local delivery of heparin to the rabbit arterial wall with an electroporation catheter

Current methods of local drug delivery frequently fail to achieve a prolonged therapeutically effective tissue drug level without producing vascular trauma. A novel double-balloon catheter system, incorporating electroporation technology, has been designed and tested to deliver heparin into rabbit carotid arteries in an overstretch balloon injury model in vivo. Following arterial injury, fluoresceinated heparin was delivered into the volume between the two inflated balloons, and the artery was subjected to an electrical pulse. Catheter deployment and endovascular electrical pulsing were well-tolerated in all animals (N = 21) without adverse hemodynamic and histological changes. Periodic arterial blood samples revealed no abnormalities in the clotting profile or any gross morphological changes in the blood cells up to 8 hr after treatment. Much stronger heparin fluorescence was detected throughout the vessel layers for at least 12 hr in the pulsed samples compared to the control. Histochemical staining of the tissue showed intracellular localization of heparin. Endovascular electroporation may provide better retention and higher therapeutic efficacy than can be achieved by conventional systemic delivery of heparin at clinically safe concentrations.

Treatment of thrombotic saphenous vein bypass grafts using local urokinase infusion therapy with the Dispatch catheter

Percutaneous treatment of thrombotic stenoses or total occlusions in aged saphenous vein bypass grafts is associated with a significant incidence of complications primarily related to distal embolization. The purpose of this study was to assess the efficacy of local urokinase delivery with the Dispatch catheter prior to balloon angioplasty and/or intragraft stent placement as a new technique of vein graft revascularization. Local urokinase delivery with the Dispatch catheter was performed in 15 saphenous vein grafts (mean age = 11.7 +/- 2.5 yr) in 13 patients with unstable or postinfarction angina. The target lesion was a total occlusion in 5 of the procedures and a severe vein graft stenosis in the remaining 10. In all cases, urokinase was administered directly to the site of the stenosis/occlusion via the Dispatch catheter at 0.5 cc/min and at a concentration of 30,000 units/cc. The mean urokinase infusion time for the 15 procedures was 33 +/- 10 min (range = 10-60 min) and the mean urokinase dose was 495,000 +/- 158,000 units (range = 150,000-900,000 units). Following Dispatch therapy, mean minimal lumen diameter increased from 0.34 +/- 0.32 to 1.81 +/- 0.78 mm (P < 0.01), mean TIMI flow increased from 1.9 +/- 1.4 to 2.8 +/- 0.8 (P < 0.06), and mean thrombus score was reduced from 2.3 +/- 0.6 to 0.3 +/- 0.8 (P < 0.01). Mild no reflow was noted in two cases, although no patient demonstrated angiographic evidence of gross distal embolization. One of the patients with no reflow also demonstrated a small increase in cardiac enzymes. Subsequent balloon angioplasty/stent placement was successful in 14 of the 15 procedures (93% success rate). This preliminary report suggests that pretreatment of thrombotic saphenous vein graft stenoses with local urokinase delivery via the Dispatch catheter may decrease intragraft thrombus and possibly decrease the incidence of vascular complications associated with percutaneous intervention. This technique may allow for recanalization of totally occluded vein grafts with large clot burdens by using significantly less urokinase and shorter drug administration times than conventional infusion protocols.

Recanalization of totally occluded saphenous vein grafts using local urokinase delivery with the Dispatch catheter

Current techniques for the percutaneous revascularization of totally occluded vein grafts are limited by a low initial success rate, a significant incidence of distal embolization, and a high rate of early graft reclosure. This case report describes two patients in whom graft recanalization was attempted with the combined use of balloon angioplasty/intra-graft stent placement and local urokinase delivery using a new angiotherapy catheter. Successful recanalization was achieved in both patients without major complications, in spite of a large thrombus burden as demonstrated by angiography.

Percutaneous revascularization of chronic coronary occlusions: an overview

Patients with a chronic coronary occlusion often undergo coronary angiography after weeks to months of occlusion. The published reports underestimate the extent of this problem because such patients are often arbitrarily assigned to receive medical therapy or undergo bypass surgery as a result of poor success with percutaneous revascularization and substantial restenosis. Thus, there is controversy about the role of angioplasty in this patient cohort. The goal of this overview was to evaluate the available information about angioplasty in chronic coronary occlusions. The primary indication for attempted recanalization of a chronic coronary occlusion has been symptomatic angina pectoris. Anginal status often improves after successful procedures (70% vs. 31% with a failed procedure); left ventricular function may improve; and subsequent referral for coronary artery bypass graft surgery is uncommon (3% vs. 28% in unsuccessful cases). Successful recanalization is achieved in approximately 65% of attempted procedures. Inability to cross the stenosis with a guide wire is the most common cause of procedural failure. Statistically significant predictors of procedural success include older occlusions (75% < 3 months old vs. 37% > or = 3 months old), absence of any anterograde flow through the occlusion (76% with vs. 58% without), angiographically abrupt-appearing occlusions (50% vs. 77% with tapered occlusions), presence of bridging collateral vessels (23% with vs. 71% without) and lesions > 15 mm. Procedural complications occur at a slightly lower incidence than in angioplasty of high grade subtotal stenoses. Long-term success is limited, and restenosis can be expected in > 50% of the patients. The experience with chronic total occlusions of saphenous vein bypass grafts is small, but there appear to be limited procedural success and significant procedural complications, particularly associated with distal emboli. The role of new pharmacologic agents has yet to be defined and that of new devices has been disappointing so far, but further technologic advances are on the horizon.

Antithrombotic and thrombolytic therapy in patients undergoing coronary artery interventions: a review

The controlled arterial injury that occurs with balloon angioplasty and other coronary interventions is characterized by evanescent endothelial denudation and vascular disruption. As a consequence, platelet activation occurs at the treated site, and there is a risk of thrombotic occlusion. This risk is heightened by several factors including unstable clinical presentation, lesion complexity, deep injury, and dissection. Aspirin has been shown to unquestionably reduce, although not eliminate, acute complications and is now part of the routine periprocedural regimen. Heparinization with more intense anticoagulation than is conventionally used is also standard treatment and is initiated before vessel instrumentation. Adjunctive thrombolysis is rarely necessary unless refractory thrombus precedes or complicates the procedure. However, thrombolysis may have a role in the treatment of saphenous vein graft obstructive lesions in which guide wire- or catheter-induced distal thromboembolization may cause infarction in spite of successful graft recanalization. In contrast to their success in the periprocedural phase of coronary interventions, anticoagulants and a wide variety of platelet active agents have been ineffective in reducing the 30% to 40% incidence of restenosis. Only 7E3, which targets the final common pathway of platelet aggregation by irreversibly blocking the IIb/IIIa receptor, has been shown to decrease the 6-month clinical event rate after balloon angioplasty, possibly by a surface pacification mechanism. This suggests that newer more potent antiplatelet and anticoagulant agents may also find a role in the long-term management of these patients.

Clinical significance of distal embolization after transluminal extraction atherectomy in diffusely diseased saphenous vein grafts

Standard balloon angioplasty of degenerated saphenous vein graft lesions may be complicated by distal embolization, particularly in the presence of intragraft thrombus. Transluminal extraction atherectomy may be useful in this setting because of its ability to remove particulate debris. This study was designed to identify the incidence and prognostic significance of distal embolization after transluminal extraction atherectomy in high-risk saphenous vein graft lesions. To address these issues the clinical course of 65 consecutive patients (86 high-risk saphenous vein graft lesions) was reviewed after extraction atherectomy. Distal embolization occurred in 11 (12.8%) of 86 high-risk lesions. The majority (63.6%) of these episodes occurred after adjunct balloon dilatation following uncomplicated use of the extraction atherectomy catheter. Correlates of distal embolization included patient age and the presence of intragraft thrombus. Major in-hospital complications developed more often in patients with distal embolization (46% vs 2% in those without distal embolization, p < 0.001), resulting in a reduced procedural success rate in this group (55% vs 91%, p = 0.01). We conclude that the risk of distal embolization after saphenous vein graft angioplasty, although potentially reduced, is not eliminated with transluminal extraction atherectomy, particularly in lesions with superimposed thrombus.

Initial and long-term outcome of 83 patients after balloon angioplasty of totally occluded bypass grafts

OBJECTIVES

This study was designed to evaluate the safety and short- and long-term results of coronary angioplasty of totally occluded bypass grafts in patients with clinical conditions other than acute myocardial infarction.

BACKGROUND

Total occlusion of bypass grafts after coronary artery surgery often causes recurrent ischemia. The safety and results of percutaneous transluminal coronary angioplasty in occluded bypass grafts are controversial.

METHODS

All patients with dilation of a totally occluded bypass graft attempted between 1981 and 1991 were retrospectively identified from a data base. Patients treated in the setting of an acute myocardial infarction were excluded. Eighty-three patients met these criteria and constitute the study group. Hospital records, office charts and procedural reports were reviewed in all patients to supplement details available in the data base.

RESULTS

The time from bypass surgery to attempted coronary angioplasty ranged from 1 to 226 months (mean time 88 months). The mean (+/- SD) duration of graft occlusion was 31 +/- 46 days (range 1 to 180). In 27 attempts the bypass graft was the only site dilated, and in 56 attempts (68%) one to six other sites (n = 101) were dilated. Angiographic success (< or = 40% residual lumen stenosis) was achieved in 61 grafts (73%) and 98 of the additional sites (97%) (p < 0.001). Major complications included one procedural death and two Q wave infarctions. Follow-up for a mean of 32 months demonstrated a 1- and 3-year actuarial survival rate of 94% and 80%, respectively. At 3 years, only 34% of patients were free of repeat angioplasty or surgery.

CONCLUSIONS

Angioplasty of totally occluded bypass grafts can be successful in the majority of selected patients, although major complications can occur. Strategies for sustained patency are needed to improve the long-term results.

Acute results and long-term outcome of transluminal extraction catheter atherectomy for saphenous vein graft stenoses

Distal embolization of atheroma and thrombus is a major concern when performing balloon angioplasty in coronary saphenous vein grafts (SVGs). The transluminal extraction catheter (TEC) is designed to remove this material and may improve the safety of percutaneous treatment of SVG disease. We assessed the acute results and long-term outcome of 67 patients (mean age 65.6 +/- 8.1 years; range 47-83 years) who underwent 73 separate TEC atherectomy procedures. Eighty-eight SVG lesions were treated (mean age 8.7 +/- 3.8 years from bypass surgery). Procedural success (< 50% final diameter stenosis and absence of major complications) was obtained in 63 patients (86%). Adjunctive balloon angioplasty and/or directional coronary atherectomy was required in 69 of the procedures (95%). Major complications, occurring in 8 patients (11%), were acute closure in 4 (5%), resulting in Q-wave myocardial infarction in 3 and urgent bypass surgery in 1, and distal embolization in 4 (5%; 1 associated with Q-wave myocardial infarction). Angiographic follow-up was available for 50 patients and restenosis was present in 26 (52%). These data suggest TEC atherectomy can be performed in SVGs with an acceptable procedural risk, but restenosis remains a significant limitation which will require other strategies to overcome.

Acute occlusion of a remote coronary artery complicating directional coronary atherectomy

Two cases of acute occlusion in a remote coronary artery complicating directional coronary atherectomy are reported. In neither case was there definite angiographic evidence of spasm, dissection, or embolization. Since this complication is seldom seen with coronary angioplasty, it may represent a relatively specific risk of directional atherectomy.

Acute myocardial infarction complicating urokinase infusion for total saphenous vein graft occlusion

Saphenous vein graft occlusions have been successfully treated with extended urokinase infusions. We report a case of myocardial infarction complicating this treatment. A review of reported cases suggests that this complication may not be uncommon. The optional drug, dose, and infusion technique for intra-graft lytic therapy has not been determined. The costs, risks, and difficulty of this technique may limit its application.

Results of coronary angioplasty using the transluminal extraction catheter

To assess the procedural results after coronary angioplasty using the transluminal extraction catheter (TEC) in patients with complex lesion anatomy, experience with 51 patients undergoing this procedure was reviewed. One or more adverse lesion morphologic features were present in 45 patients (88%) and > or = 2 adverse features were present in 38 (74%). Procedural success (< 50% final diameter stenosis and the absence of major complications) was obtained in 42 patients (82%); major complications occurred in 7 patients (death, 3; Q-wave myocardial infarction, 4; emergency bypass operation, 2). Distal embolization was noted in 5 patients with thrombus-containing saphenous vein graft stenoses. Only lesion thrombus correlated with an unsuccessful outcome. After TEC use, diameter stenosis was reduced from 76 +/- 13 to 50 +/- 22% (p < 0.001). Adjunct balloon angioplasty was used in 44 procedures (86%), further reducing the diameter stenosis to 32 +/- 22% (p < 0.001 compared with post-TEC). High-frequency intracoronary ultrasound was performed in 11 patients after TEC use. Plaque fissuring was present in all lesions and intraluminal dissection was noted in 4 (36%). Residual plaque after TEC use was found in virtually all lesions. During the 5.2 +/- 2.8-month follow-up period, 17 patients (40%) developed recurrent symptoms. Coronary bypass surgery was performed in 4 patients and repeat coronary angioplasty was required in 3. In addition, 3 patients died from cardiac causes. It is concluded that coronary angioplasty using the TEC may be a useful alternative to balloon angioplasty in patients with complex coronary anatomy, although distal embolization may still occur in thrombus-containing saphenous vein graft lesions.