Michael Azrin

The VIVA Trial

Background—Recombinant human vascular endothelial growth factor protein (rhVEGF) stimulates angiogenesis in animal models and was well tolerated in Phase I clinical trials. VIVA (Vascular endothelial growth factor in Ischemia for Vascular Angiogenesis) is a double-blind, placebo-controlled trial designed to evaluate the safety and efficacy of intracoronary and intravenous infusions of rhVEGF. Methods and Results—A total of 178 patients with stable exertional angina, unsuitable for standard revascularization, were randomized to receive placebo, low-dose rhVEGF (17 ng · kg−1 · min−1), or high-dose rhVEGF (50 ng · kg−1 · min−1) by intracoronary infusion on day 0, followed by intravenous infusions on days 3, 6, and 9. Exercise treadmill tests, angina class, and quality of life assessments were performed at baseline, day 60, and day 120. Myocardial perfusion imaging was performed at baseline and day 60. At day 60, the change in exercise treadmill test (ETT) time from baseline was not different between groups (placebo, +48 seconds; low dose, +30 seconds; high dose, +30 seconds). Angina class and quality of life were significantly improved within each group, with no difference between groups. By day 120, placebo-treated patients demonstrated reduced benefit in all three measures, with no significant difference compared with low-dose rhVEGF. In contrast, high-dose rhVEGF resulted in significant improvement in angina class (P =0.05) and nonsignificant trends in ETT time (P =0.15) and angina frequency (P =0.09) as compared with placebo. Conclusions—rhVEGF seems to be safe and well tolerated. rhVEGF offered no improvement beyond placebo in all measurements by day 60. By day 120, high-dose rhVEGF resulted in significant improvement in angina and favorable trends in ETT time and angina frequency.

Effect of lovastatin on intimal hyperplasia after balloon angioplasty : a study in an atherosclerotic hypercholesterolemic rabbit

Restenosis, the major limitation of balloon angioplasty, is the result of intimal hyperplasia after the procedure. Lovastatin, a 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) inhibitor, may influence intimal hyperplasia by lowering serum cholesterol and by blocking deoxyribonucleic acid (DNA) synthesis. To determine whether lovastatin reduces intimal hyperplasia, a prospective, randomized blinded study was performed in 60 atherosclerotic New Zealand White male rabbits. Atherosclerosis was produced by air desiccation injury followed by a 28 day diet of 2% cholesterol and 6% peanut oil that was terminated before balloon angioplasty was performed. Angioplasty could not be performed in 14 rabbits with bilateral femoral artery occlusion, and in one rabbit the procedure was a technical failure. Forty-five rabbits underwent balloon angioplasty performed with use of a 2.5-mm balloon inflated to 10 atm for three 1 min dilations at 1 min intervals. Seven rabbits died during the procedure. Thirty-eight rabbits were randomized to either a lovastatin group (6 mg/kg body weight per day) or a control group. Angioplasty was performed on all patent vessels (n = 54); the procedure was bilateral in 16 rabbits and unilateral in 22. Fifteen lovastatin-treated and 15 control rabbits survived 39 days after angioplasty and were then killed. Angiograms, obtained before and 10 min and 39 days after balloon angioplasty, were read with use of electronic calipers by two observers who had no knowledge of treatment data. After the rabbits were killed, vessels were pressure perfused using a standardized protocol to maintain in vivo dimensions for blinded quantitative histologic analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Decreased platelet deposition and smooth muscle cell proliferation after intramural heparin delivery with hydrogel-coated balloons.

In vitro and in vivo studies have demonstrated both anticoagulant and antiproliferative effects of heparin. The purpose of this study was to assess the effect of local intramural delivery of heparin, using heparin-coated hydrogel balloons, on platelet deposition and early smooth muscle cell proliferation after in vivo balloon angioplasty. Methods and ResultsThe effects of local heparin delivery were assessed during balloon angioplasty of porcine peripheral arteries. All balloon dilatations were performed with oversized hydrogel balloons coated with a known quantity of heparin. Balloon dilatations in contralateral vessels with uncoated hydrogel balloons served as study controls. The pharmacokinetics of heparin delivery were assessed using 3H-heparin to quantitate heparin wash-off from the balloon surface, heparin delivery to the arterial wall, and intramural persistence of drug. Platelet deposition at 1 hour after balloon injury was quantified using 111In-labeled platelets. Smooth muscle cell proliferation was assessed 6 to 7 days after angioplasty with immunohistochemical staining for proliferating cell nuclear antigen. 3H-heparin wash-off from the hydrogel balloon surface occurred rapidly, with approximately 95% of the heparin coating disappearing within 10 seconds in the intact circulation. Approximately 2% of heparin on the balloon surface was delivered intramurally at the time of angioplasty. Intramural heparin dissipated rapidly, although small amounts of intramural heparin could still be detected for at least 48 hours. In comparison to control vessels, there was less 111In-platelet deposition (P = .002) and less medial smooth muscle cell proliferation (P = .03) in heparin-treated vessels. ConclusionsLocal intraluminal delivery of heparin at the time of balloon angioplasty with heparin-coated hydrogel balloons results in intramural deposition of drug that persists for at least 48 hours. This in vivo technique significantly decreases platelet deposition and early smooth muscle cell proliferation after angioplasty injury.

Antithrombotic Potential of Polymer-Coated Stents Eluting Platelet Glycoprotein IIb/IIIa Receptor Antibody

BACKGROUND Monoclonal anti-rabbit platelet glycoprotein (GP) IIb/IIIa antibody (AZ1) was adsorbed onto cellulose polymer-coated intracoronary stents to enhance their thromboresistance. We evaluated the antithrombotic efficacy of AZ1 antibody-eluting stents. METHODS AND RESULTS Twenty-three polymer-coated stents with AZ1 antibody bound by passive adsorption (AZ1-eluting) were compared with 23 control polymer-coated stents adsorbed with either no antibody (base-polymer, n = 12) or isotype-matched irrelevant antibody (anti-CMV-eluting, n = 11) by implantation into balloon-damaged, flow-reduced iliac arteries of New Zealand White rabbits. In 13 animals (acute group), flow measurements were made with transit-time flow probes and platelet adhesion was ascertained by use of 111In-labeled autologous platelets. In the other 10 animals (chronic group), stent occlusion was assessed macroscopically after they were killed 28 days after stenting. Arteries with AZ1-eluting stents had significantly less platelet deposition (15.8 +/- 4.5 x 10(7)) than either base-polymer (32.1 +/- 4.3 x 10(7)) or anti-CMV-eluting (35.2 +/- 8.8 x 10(7)) controls (ANOVA, P < .0001). Compared with base-polymer or anti-CMV-eluting controls, arteries with AZ1-eluting stents showed a marked reduction in cyclic blood flow variation (P < .0001) and a significantly greater mean blood flow 2 hours after stent deployment (P < .0001). There was a significant improvement in the patency rate of AZ1-eluting stents compared with controls at both 2 hours (92% versus 46%, P = .034) and 28 days (100% versus 40%, P = .015). CONCLUSIONS Platelet GP IIb/IIIa antibody eluting from polymer-coated stents reduces platelet deposition, improves blood flow, virtually abolishes cyclic flow variation, and improves patency rates after stent implantation in a rabbit iliac artery model. Its potential for reducing stent-related thrombosis in humans warrants further evaluation.

Abciximab and bleeding during coronary surgery: results from the EPILOG and EPISTENT trials ∗

BACKGROUND Abciximab during percutaneous coronary revascularization reduces ischemic complications, but concern exists regarding increased bleeding risk should emergency coronary surgical procedures be required. METHODS Outcomes were assessed among 85 patients who required coronary artery bypass grafting operations after coronary intervention in two randomized placebo-controlled trials of abciximab. Comparisons were made between patients in the pooled placebo and abciximab groups. RESULTS The incidence of coronary surgical procedures was 2.17% and 1.28% among patients randomized to placebo and abciximab, respectively (p = 0.021). Platelet transfusions were administered to 32% and 52% of patients in the placebo and abciximab groups, respectively (p = 0.059). Rates of major blood loss were 79% and 88% in the placebo and abciximab groups, respectively (p = 0.27); transfusions of packed red blood cells or whole blood were administered in 74% and 80% of patients, respectively (p = 0.53). Surgical reexploration for bleeding was required in 3% and 12% of patients, respectively. Death and myocardial infarction tended to occur less frequently among patients who had received abciximab. CONCLUSIONS Urgent coronary artery bypass grafting operations can be performed without an incremental increase in major hemorrhagic risk among patients on abciximab therapy.

Localized intramural drug delivery during balloon angioplasty using hydrogel-coated balloons and pressure-augmented diffusion

OBJECTIVES This study was designed to assess the feasibility of using hydrogel-coated balloons to deliver biologically active agents to the blood vessel wall. BACKGROUND The local intramural delivery of therapeutic agents during balloon angioplasty has been proposed as an adjunctive technique for preventing early intracoronary thrombosis and late restenosis. METHODS To assess the efficacy of delivery and depth of penetration in vitro, local delivery of horseradish peroxidase was performed in 40 porcine peripheral arteries, and delivery of fluoresceinated heparin was performed in 20 porcine peripheral arteries and 7 human atheromatous arteries. To determine the persistence of these agents in the vessel wall in vivo, horseradish peroxidase was delivered to 18 porcine peripheral arteries that were harvested at intervals of 45 min to 48 h. Fluoresceinated heparin was delivered to 22 porcine peripheral arteries, 14 with the use of a protective sleeve, harvested at intervals of 30 s to 24 h. RESULTS In vitro agent delivery was successful in all specimens. The depth of penetration of horseradish peroxidase was directly related to both balloon pressure (p < 0.04) and duration of inflation (p < 0.01). In vivo peroxidase staining was evident at 45 and 90 min but not thereafter. With the use of a protective sleeve, heparin was present in all arteries harvested at 30 s, with marked dissipation at 1 and 24 h. Without a sleeve, no fluorescein staining was detected in any artery. With both agents, delivery occurred consistently over broad regions of the vessel wall that were free of architectural disruption. CONCLUSIONS Hydrogel-coated balloons can deliver biologically active agents to the vessel wall without gross tissue disruption and may provide an atraumatic method for the local delivery of therapeutic agents during balloon angioplasty.

INHIBITION OF PLATELET DEPOSITION AND LYSIS OF INTRACORONARY THROMBUS DURING BALLOON ANGIOPLASTY USING UROKINASE-COATED HYDROGEL BALLOONS

BACKGROUND Conventional balloon angioplasty of intracoronary thrombus is associated with a high incidence of abrupt closure, distal embolization, and no-reflow phenomenon. The purpose of this study was to assess a new technique for treating intracoronary thrombus consisting of the local delivery of urokinase directly to the angioplasty site with urokinase-coated hydrogel balloons. METHODS AND RESULTS We assessed local urokinase delivery using hydrogel balloons in four protocols. First, we evaluated the pharmacokinetics of urokinase delivery in vitro using 125I-labeled urokinase to measure drug loading onto hydrogel balloons, drug retention by the hydrogel polymer during blood exposure, and drug transfer from the balloon surface to the arterial wall during balloon dilatation. Second, we measured 125I-urokinase washoff from the hydrogel balloon in the intact circulation and intramural drug delivery during in vivo balloon angioplasty in 10 anesthetized New Zealand rabbits. Third, we assessed the effect of local urokinase delivery on 111In-labeled platelet deposition after balloon angioplasty in vivo in 13 porcine carotid or iliac arteries dilated with urokinase-coated balloons and compared them with contralateral control arteries dilated with saline-coated balloons. Finally, we determined the clinical efficacy of urokinase-coated balloons in 15 patients with intracoronary thrombus, including 7 who demonstrated abrupt thrombotic closure after conventional angioplasty. Between 241 and 1509 U urokinase could be loaded onto hydrogel balloons ranging in size from 2 to 8 mm. In vitro and in vivo studies demonstrated that hydrogel balloons absorbed significantly more urokinase and demonstrated less drug wash-off than nonhydrogel balloons (P < .01). Similarly, both in vitro and in vivo studies demonstrated urokinase transfer from the hydrogel to the arterial wall during balloon angioplasty, with greater intramural drug deposition with larger balloons (P < .01). Local urokinase delivery after in vivo porcine angioplasty decreased 111In-labeled platelet deposition by 47% compared with contralateral control vessels (P = .03). Use of urokinase-coated balloons in patients with intracoronary thrombus resulted in thrombus dissolution and reversal of abrupt closure in all cases, without evidence of distal embolization. CONCLUSIONS With the use of hydrogel-coated balloons, urokinase can be delivered locally to an angioplasty site. This technique decreases platelet deposition after in vivo balloon angioplasty and is efficacious in treating intracoronary thrombus in patients, including those with abrupt thrombotic closure.

Beneficial effect of glycoprotein IIb/IIIa inhibitor (AZ-1) on endothelium in Escherichia coli endotoxin-induced shock.

Objective To investigate the effects of AZ-1, a murine monoclonal antiglycoprotein-IIb/IIIa antibody, on endothelium and on hemostasis in a rabbit endotoxic shock model. Design Prospective laboratory study. Setting University laboratory. Subjects Thirty-five male New-Zealand rabbits. Interventions In vitro vascular reactivity, endothelium CD31-PECAM1 immunohistochemistry, plasma coagulation factors, and monocyte tissue factor determination were performed 1 day and/or 5 days after onset of endotoxic shock (0.5 mg/kg, intravenous bolus, Escherichia coli lipopolysaccharide) with or without treatment by AZ-1 (0.5 mg/kg intravenously) given 1 hr after lipopolysaccharide injection. Measurements and Main Results Metabolic acidosis and coagulation activation confirmed the presence of shock. AZ-1 treatment improved endothelial-dependent relaxation at 1 day (maximal effect = 87.2 ± 4.0% vs. 60.9 ± 5.2% in the nontreated group, p < .05) and at 5 days (maximal effect = 84.5 ± 3.5% vs. 56.6 ± 8.2% in the nontreated group, p < .05). Endotoxin-induced endothelial injury was decreased significantly by AZ-1 at 1 day (6.4 ± 1.9% vs. 10.3 ± 0.8% in the nontreated group, p < .05) and at 5 days (6.3 ± 2.0% vs. 20.2 ± 1.2% in the nontreated group, p < .05). Monocyte tissue factor expression was significantly reduced at 5 days. Conclusions These data indicate that potent inhibition of platelet function via antiglycoprotein-IIb/IIIa receptor blockade can inhibit coagulation activation and protect against endothelial dysfunction and histologic injury in endotoxin-induced shock.

Preparation, characterization, and evaluation of a monoclonal antibody against the rabbit platelet glycoprotein IIb/IIIa in an experimental angioplasty model.

The deposition of platelets at the site of balloon angioplasty is thought to play a major role in the pathogenesis of restenosis. The antibody AZ-1, which binds to the rabbit platelet glycoprotein IIb/IIIa receptor and inhibits platelet function both in vitro and in vivo, was produced and tested in an experimental model of angioplasty. Atherosclerosis was induced by desiccation injury of the femoral artery, followed by a 28-day diet with 2% cholesterol and 6% peanut oil. Rabbits were randomized to receive an infusion of saline, a single infusion of 0.5 mg/kg of AZ-1, or an infusion of 0.6 mg/kg AZ-1 before angioplasty. The latter group received a second infusion of 0.6 mg/kg 72 hours later. Functional platelet inhibition was demonstrated by prolongation of the bleeding time in all treated animals. Angiography was performed at baseline, immediately after a standardized angioplasty, and again 28 days after angioplasty on a total of 42 vessels. There were no significant differences between the antibody-treated group and the control group in the mean angiographic minimum luminal diameter at any of the time points. There was also no difference in the initial improvement after angioplasty (acute gain), in the decrease in luminal diameter from immediately after angioplasty to 28 days after angioplasty (late loss), or in the overall improvement from before angioplasty to 28 days after angioplasty. Quantitative histological analysis confirmed the lack of a beneficial effect of AZ-1. There were no significant differences in the area of the intima, the media, or the combined intima and media between the antibody-treated groups and the control group. Thus, potent platelet inhibition for up to 6 days after balloon angioplasty using a monoclonal antibody that inhibits platelet aggregation did not reduce the response to vascular injury after balloon angioplasty in this rabbit model of experimental atherosclerosis.

Serum Caspase-3 p17 Fragment Is Elevated in Patients With ST-Segment Elevation Myocardial Infarction: A Novel Observation

To the Editor: Infarct size is a major determinant of mortality after acute myocardial infarction (AMI) ([1][1]). Although timely reperfusion of the ischemic myocardium in patients with ST-segment elevation myocardial infarction (STEMI) is the most effective way to limit infarct size, reperfusion