Cardiac Pressure: To Stent or Not to Stent

Since the FDA first approved the use of stents in 1993, stenting has moved beyond a lifesaving procedure and turned into a highly profitable business. However, amid the stenting ‘boom’ of the last 20 years several studies have been published supporting the idea that stents are being overused. Additional studies have found less costly drug therapies to be just as effective, if not more, at treating patients with stable coronary disease when compared to stenting. This, combined with lawsuits, mounting public discourse over the controversy and insurance carriers pushing for more stringent justifications for stenting have led physicians to be more selective.

In the past the decision to stent or not was a qualitative one based on visual assessment by the physician that utilized traditional fluoroscopic x-ray imaging and more recently the non-radiation based imaging techniques, specifically intra-vascular ultrasound(IVUS). The light-based technology Optical Coherence Tomography (OCT) is the newest edition to the imaging repertoire. Both IVUS and OCT, despite being based on a visual assessment, have moved the decision process closer to a measurement based metric for lesion size, shape and length with the ability to measure two dimensional images. These technologies have made the greatest difference in helping physicians to decide the size of the stent to use, evaluating the degree of deployment and the length of the stent. In some cases they have also helped with the positioning of dual stents in an end-to-end presentation.

The IVUS vendors in this arena have been Boston Scientific (iLab) and Volcano (s5) systems. The OCT technology is currently only available through St. Jude Medical with their Illumien. All three devices require proprietary consumables (catheters) but there are some distinct differences as noted in the chart below:

6.6.13

For example, while IVUS does not provide as high a resolution as OCT, imaging can be done without additional contrast or imaging injection. IVUS also allows for a slower pullback that may be helpful in longer lesions. On the other hand, OCT provides much higher image quality and may eventually provide advantages in assessing not only the physical nature of the lesion, but also the cellular makeup of the lesion. Another key difference is that OCT can only be used for coronary work and is not practical in larger vessels found in peripheral work.

Interest in both technologies has been growing over the years and we’ve seen this reflected in MD Buyline quote activity as well with a 28% market jump since last year. The introduction of St. Jude’s OCT technology has brought additional changes to the market. Three years ago, Volcano’s quote level was 70% of what came in to MDB, Boston Scientific was 30% and St. Jude was negligible. In the 2011/2012 time frame, Volcano still held the lead at 72%, but Boston Scientific lost some ground settling in at 8% and St. Jude’s impact on the market was observed with their 20% claim. We’ve seen this trend hold in the past 12 month as seen in the graph below which is based on quotes sent to MD Buyline for purchase consideration.

6.6.13_3

As significant as IVUS and now OCT has been to the evolution of therapeutic interventional cardiovascular medicine, another technology has even more recently begun to have an even greater impact on the clinical decision process regarding stenting. This is a technology called Fractional Flow Reserve (FFR) and was first introduced in the 1990s by Cardiometrics which after many different acquisitions was eventually acquired by Volcano Therapeutics in 2003. While this technology has been around for many years it has only recently emerged as the real focus for stent-based decisions. It allows direct measurement of the pressure inside the diseased vessel via a small pressure transducer mounted on a wire. By measuring the pressure difference from the near or proximal side of the lesion versus the far or distal side of the lesion the system can calculate an FFR value that provides a real measure of how that lesion is physiologically impacting the blood flow across the blockage. The image below depicts how FFR is calculated.

6.6.13_2

Clinical trials in the FAME and DEFER studies have consistently shown that FFR values less than 0.80 benefit from stenting and those above 0.80 typically do not result in sustained positive outcomes. There continues to be some physician discretion in the range just below or above the 0.80 figure depending on anatomy and other risk factors, but it has provided a more definitive metric to determine when stenting a patient is appropriate.

Currently the only players in the FFR market are Volcano and St. Jude, but Guided Interventions, a Cleveland startup, is in the developmental stages of their FFR wire. Initially FFR was only sold as stand-alone, add-on technology but both vendors have now incorporated the FFR technology into their respective IVUS/OCT solutions providing an integrated solution for the interventional physicians. This integration which provides clinicians with a single, multi-functional system to better handle therapeutic decisions in the cath lab is why both Volcano and St. Jude’s technology have been so successful.

I believe this is becoming, if it is not already, the standard of care for cardiac interventional programs. Advancements will continue to be made and the decision on whether to use IVUS or OCT will be one of the factors. At MD Buyline we are beginning to see some facilities using both.

If you are interested in more in-depth information on vessel imaging devices as well as the coronary artery stent market then please contact member.services@www.mdbuyline.com to get a recording of last week’s webinar ‘Beyond the Debate: The Financial & Clinical Impact of Over-Stenting” where we shared more detailed information

If you are not a member, please take a look at the Coronary Artery Stents Buyers Brief that we created for HFMA that also offers a detailed look.

Tom Watson, BS, RCVT
ABOUT THIS EXPERT
Tom Watson, BS, RCVT, Clinical Analyst — Mr. Watson joined MD Buyline in 1986 and has over 40 years of experience in the field of cardiovascular medicine. At MD Buyline, Mr. Watson's primary responsibility is invasive cardiovascular technology - interventional angiography, electrophysiology imaging and monitoring, cardiology PACS and information systems and a number of other areas. He graduated with a Bachelor of Science degree from Louisiana State University. He received registries in both noninvasive and invasive cardiovascular modalities through the National Society of Cardiopulmonary Technologies, as well as adult echocardiography through the American Registry of Diagnostic Medical Sonographers.