InTouch Magazine - Fall/Winter 2000

The Interventional Cardiology Research Program at the Minneapolis Heart Institute Foundation: Revolutionary New Devices to Treat Coronary Artery Disease

Treatment options for patients with coronary artery disease have expanded dramatically in the past decade, significantly decreasing the need for coronary bypass surgery for many patients. The new treatment options fall under the category of interventional cardiology, which involves inserting a catheter percutaneously (through the skin) to treat coronary blockages.

Originally, interventional cardiology was comprised solely of coronary balloon angioplasty, which was invented in 1977 primarily to treat single vessel disease. The field of interventional cardiology, with its new technologies and devices, has expanded so extensively that this year nearly 800,000 coronary interventional procedures will be performed in the United States.

In this issue, InTouch looks at the Interventional Cardiology Research Program at the Minneapolis Heart Institute Foundation and Abbott Northwestern Hospital and reviews a variety of interventional devices and treatments currently available.

The Interventional Cardiology Research Program at the Minneapolis Heart Institute Foundation (MHIF) and Abbott Northwestern Hospital was started 13 years ago when the Interventional Cardiology database was initiated for the purposes of tracking procedural outcomes and conducting prospective research studies. Since then, nearly 20,000 patients have been entered into the database.

The Interventional Cardiology Research Program team includes research coordinators and the data analysis experts who maintain the database, screen and enroll patients in research studies, and educate patients and families before and after their procedures. The team also contacts each patient by telephone for a six-month follow-up evaluation.

This expansive research effort has resulted in a tremendous growth in interventional cardiology research endeavors at the Minneapolis Heart Institute Foundation and has fostered extensive journal publications and presentations at national cardiology scientific sessions.

The clinical and research programs are complemented by an established fellowship training program in interventional cardiology that is co-sponsored by the University of Minnesota.

Technological advances during the past decade have revolutionized the percutaneous approach to coronary artery disease. There is a variety of effective devices now available. Which device to use is tailored to each patient's individual case.

Coronary Balloon Angioplasty (PTCA)
Enormous advances have taken place in balloon angioplasty technology since its introduction in 1977. Although PTCA is a safe and effective treatment for coronary disease, there remains a significant incidence of restenosis (renarrowing of the artery blockage) and a higher incidence of complications than with newer treatment options. PTCA continues to be the device of choice for smaller coronary arteries with success rates averaging approximately 90%.

Coronary Stents
Coronary stents represent the single most significant advance in the percutaneous treatment of coronary disease. Coronary stents are metallic tubes that act as a scaffold within a coronary blockage. Stents improve initial results, decrease complications and significantly reduce restenosis. Coronary stenting is the device of choice in more than 80% of interventional procedures. Coronary stents have expanded the treatment options for many patients thereby preventing or delaying the need for bypass surgery.

Atherectomy Devices
Coronary atherectomy devices were introduced to treat coronary blockages in the late 1980s. Directional atherectomy removes the plaque blocking coronary arteries with a cutting chamber device. Although directional atherectomy produces good initial results, the goal of reducing restenosis rates has not been demonstrated. Directional atherectomy may have a role in patients who are not candidates for stenting. Rotational atherectomy uses a device that rotates at high speed to pulverize plaque into tiny particles. Rotational atherectomy is most frequently used for heavily calcified blockages and for some types of in-stent restenosis. Atherectomy devices have a smaller niche than previously held and are used in less than 5% of patients.

Program Highlights Staff of 10 interventional cardiology physicians and 5 research staff. Established fellowship training program in Interventional Cardiology. Participated in more than 60 research studies. Published 4 book chapters, 65 manuscripts and 150 abstracts. Performed the first intracoronary stent and directional atherectomy in Minneapolis. First to investigate the Duett Sealing Device, in-stent radiation and sonotherapy in the Twin Cities.

Intracoronary Ultrasound
Intracoronary ultrasound allows direct visualization of the inside of a coronary artery. Ultrasound images provide information not provided by coronary angiography. Ultrasound is especially helpful in identifying certain complications resulting from intervention, which when identified may then be repaired. Intracoronary ultrasound assessment is now used primarily in research studies at our institution.

Vascular Closure Devices
Significant progress has been made in the last decade to close the puncture site required for percutaneous intervention. For many years manual compression, c-clamps, pressure dressings and prolonged bed rest were required to ensure adequate puncture site healing. Several new vascular closure devices are currently available and extensively utilized to promote puncture site sealing. Although the devices utilize different techniques, they result in increased patient comfort, decreased length of bed rest post-procedure and shortened length of hospital stay.

The optimal medical regimen to improve initial results and long-term effectiveness is a combination of interventional procedures and medication. Preventing platelets from forming clots is vital following interventional procedures. Several intravenous platelet-inhibiting drugs (known as IIb/IIIa inhibitors) are available and used extensively in selected patients undergoing interventional procedures. These drugs can be given before, during and/or after the procedure and have been shown to significantly reduce immediate complications and improve long-term benefit. Platelet inhibitors combined with interventional procedures are used in more than 50% of patients.

Also significant in enhancing results is the optimal post-stent medical regimen. Most patients now receive aspirin and one of the newer oral platelet inhibitors following stent implantation. The use of platelet-inhibiting drugs is currently receiving intense clinical investigation across the country.

Numerous clinical research studies investigating new devices and drugs to treat coronary disease are ongoing within the Interventional Cardiology Research Program. Participating in these studies keeps the program at the forefront of new technology and allows access to state-of-the-art devices not available elsewhere within the Twin Cities.

Interventional physicians explain the procedure to patients before beginning.

Pre and post angiograms of a SAFER case: The Percusurge Guard-Wire and coronary stent placement resulted in a decrease in blockage from 90% to 0% and no dislodgement of vein graft blockage debris.

The Interventional Cardiology Research Program is currently participating in a variety of important research trials. The GAMMA trial is underway to assess the effectiveness of in-stent radiation (known as brachytherapy) for in-stent restenosis. The SILENT and SWING studies evaluate therapeutic ultrasound (known as sonotherapy) to treat renarrowing within stented arteries. The success of a new stent is being studied in the SUPORT trial. Three five-year telephone follow-up studies to evaluate the long-term effectiveness of placed stents are underway. The safety and results of using embolization protection devices (devices which prevent dislodgement of debris) in vein grafts are being evaluated in the SAFER, VESTA and GUARD trials. A registry has been established to follow the use of the Cardioseal device to seal a hole in the wall of the heart chamber in patients who have had a stroke. The DUETT study evaluated a vascular closure device (a device that quickly seals the puncture site). This device, which recently received FDA approval, permits early patient mobility following procedures performed from a groin puncture site. Two platelet-inhibiting drugs are being compared by the TARGET study in patients undergoing interventional procedures.

To meet the clinical, research and educational needs of patients undergoing coronary interventional procedures, Abbott Northwestern Hospital and the Minneapolis Heart Institute Foundation created a specially designed interventional cardiology patient care unit in 1989. This unit allows for a comprehensive approach to the education and care of inter-ventional patients following their procedures and offers the optimal setting for research in the field of interventional cardiology. The unit provides excellent continuity of patient care and has contributed to a decrease in length of hospital stay and an increase in patient and family satisfaction.

Since its inception in 1987, the Interventional Cardiology Research Program has experienced tremendous growth both in research endeavors and clinical volume. The number of patients with coronary disease treated by intervention has more than doubled. Initially, one or two research studies were conducted each year. This has evolved dramatically to approximately 15 studies a year. In fact, MHIF's Interventional Cardiology Research Program has often been the first center in the Twin Cities to investigate a new device which has impacted the treatment of coronary disease.

The Interventional Cardiology Research Program has evolved significantly over the past decade to expand the treatment options for patients, thereby preventing or delaying the need for coronary bypass surgery. This comprehensive program has dedicated expert physicians, an experienced research team, and a level of technology and service unique in the Twin Cities, which is nationally recognized for its accomplishments and commitment to excellence. In the years to come, MHIF's Interventional Cardiology Research Program is committed to making even greater strides in the treatment of coronary disease.

For further information about the Interventional Cardiology Research Program, please call Jodi Mooney, RN, MS, Director, at 612/863-3974.