New devices used to reduce arterial occlusions, provide cardiac support

Oct 12 2008

Research results highlighting three new devices used to reduce blockages in peripheral and coronary arteries and to provide cardiac support will be presented at the 20th annual Transcatheter Cardiovascular Therapeutics (TCT) scientific symposium, sponsored by the Cardiovascular Research Foundation (CRF).

The featured devices include one designed to optimize stenting of complex arterial lesions, a left ventricular assist device for patients undergoing high risk percutaneous coronary intervention and another for treating high risk diabetic and dialysis patients with peripheral artery disease.

Device used to optimize stenting of complex lesions Ehud Grenadier, M.D., abstract author, CRF faculty member, and a faculty member at Rambam Hospital affiliated with the Technion – Israel Institute of Technology will present the "Optimizing Plaque Modification in Complex Lesions Utilizing the AngioSculpt Device: Acute and Long-Term Results from a Large Two-Center Registry."

The AngioSculpt (ASC) device is designed to optimize stenting of difficult-to-treat lesions and to avoid slippage or "geographic miss." It incorporates a flexible nitinol scoring element consisting of 3 rectangular spiral struts which encircle an angioplasty balloon thereby allowing more effective plaque modification particularly of fibro-calcific lesions.

In this study, 521 patients with complex blockages in their coronary arteries were treated with percutaneous coronary intervention (PCI). Using intravascular ultrasound (IVUS) guidance in most of these patients, the ASC was used for pre-dilation and plaque-modification to optimize stent implantation (predominantly drug-eluting stents). It resulted in a high procedural success rate and excellent long-term outcomes (up to 3 years). Results included a very low rate of heart-related complications, dangerous blood clots called stent thrombosis that can form in the stent, and repeat procedures due to lesion revascularization in patients with complex disease (such as significant calcification, diffuse disease or at a bifurcation) and a high rate of diabetes.

Dr. Grenadier said that, "ASC slippage was very rare (1.2%), thereby avoiding 'geographic miss,' and the rate of significant dissections post-ASC was rare (1.5%) and much lower than the historic rate with conventional balloons (POBA) for pre-dilation. There were no perforations despite the highly complex lesions treated.

Left ventricular assist device compared to intra-aortic balloon pump
William O'Neill, M.D., of the University of Miami will present "PROTECT II: A Prospective Multicenter Randomized Controlled Trial Investigating the Use of the Impella® 2.5 versus Intraaortic Balloon Pump in Patients Undergoing Nonemergent High-Risk PCI."

This left ventricular assist device is a leading edge, novel device that helps the left ventricle, the heart's main pumping chamber work better. PROTECT II is the largest multicenter, prospective, controlled trial in patients needing high-risk percutaneous coronary intervention (PCI). Its aim is to demonstrate the superiority of Impella® 2.5 over the Intra-Aortic Balloon Pump (IABP).

The safety of the device in a high risk population was first demonstrated in the PROTECT I study. The U.S. Food and Drug Administration approved the PROTECT II study to provide a better understanding of the potential benefits of elective intra-procedural hemodynamic support for the high-risk PCI patient population. The study will enroll 654 patients at up to 150 sites. Patients will be randomized in a 1:1 ratio to the Impella or IABP arm.

In describing the aim of the study, Dr. O'Neill said, "This superiority trial is designed to show at least a 33% reduction in intra-peri-procedural major events such as death, myocardial infarction, stroke, repeat revascularization or renal dysfunction occurring up to 30 days following implantation with the Impella arm as compared to the IABP arm." Preliminary clinical progress will be presented at the meeting.

SAVE A LEG Registry
R. Stefan Kiesz, M.D., of the San Antonio Endovascular and Heart Institute and the University of Texas Health Science Center, will present "Long-Term Results of Plaque Excision Combined with Aggressive Pharmacotherapy in High-Risk Population (SAVE A LEG Registry)."

In the United States alone there are more than 12 million people with peripheral artery disease (PAD). Even more patients have untreated diabetes, hypertension, dyslipidemia, renal dysfunction as well as coronary and neurovascular disease. PAD is an underlying condition that can result in critical limb ischemia (CLI) which carries an annual amputation rate of 30% and a death rate of 25%. Initial treatment is usually peripheral bypass surgery and when it fails, amputation.

The use of the SilverHawkTM device, which is used to cut away as much plaque as possible, in high-risk diabetic and dialysis patients with PAD is aimed at reducing the rates of death or amputation caused by CLI. This is the first study to combine aggressive medical management involving plaque excision with extensive plaque pharmacotherapy involving a plaque reversal dose of statins, treatment of diabetes with the goal of strict glycemic control, and chronic therapy with antiplatelet agents. In this study, which began in November 2003, investigators treated 225 consecutive patients (138 male, mean age 66.3, range 29-93) with SilverHawk plaque excision for critical limb ischemia or disabling claudication (cramp-like leg pain). The study population was very high risk: 150 patients (68.9%) were diabetic and 74 (32.9%) had end-stage renal disease and were on dialysis. Complete occlusion was present in 104 (12.6%) lesions. One hundred and ninety four (86.2%) patients presented with critical limb ischemia.

A total of 367 excision procedures were performed treating 823 lesions. All patients were also treated with cholesterol-lowering statins, blood thinning agents (clopidogrel and aspirin) and aggressive blood sugar control.

The average time of observation was 2.2 years. The procedural success rate was 99.4% with less than 30% residual stenosis occurring in 808 (98.2%) lesions. The SilverHawkTM device was used alone in 86% lesions; just 13.4% required adjunctive therapy. No acute limb loss or major artery perforation occurred. Long term mortality was 15.6%. Fifty nine (26.2%) patients had repeat procedures for artery re-narrowing. Major amputations and mortality were drastically reduced to about 2% and 7% per year respectively.

Researchers concluded that plaque excision using the SilverHawkTM device combined with aggressive drug therapy is associated with promising long term outcomes in diabetic patients at risk of limb loss or death from CLI and compares favorably with accepted standards.

Dr. Kiesz summed up the results, stating that, "This novel, combined approach of early detection and treatment of the underlying diseases will result in a dramatic decrease in the number of amputations and mortality from PAD, as well as a substantial savings to the health care system. We learned that occlusive lesions have to be approached early with percutaneous techniques including plaque excision, angioplasty, and stenting when appropriate. Future research should focus on the combination of aggressive pharmacotherapy with extensive percutaneous interventions instead of pitting them against each other."