Medical Device Daily Washington Editor
WASHINGTON — The three-day agenda for CRT (Cardiovascular Research Technologies) 2010, sponsored by the Cardiovascular Research Institute (Washington) showed that most of the interest in cardiovascular is still in the "cardio" part of the vascular system, but at least one Sunday session refreshingly dealt with the vascularity of other parts of the body.
However, remarks heard at that session suggested that the theme of exposure to ionizing radiation is never far from the mind of the practicing physician, although the emphasis is not identical to that put forth by FDA. As was the case with TCT 2009, physicians did not voice any fears of a wave of imaging-induced cancers, although they urged caution regarding potential patient overexposure. This time, however, one doctor said he is of the view that the healthcare provider is the entity most in harm's way.
Added to the fact that a lot of physicians feel that intravascular ultrasound (IVUS) offers a better picture of the compromised blood vessel in many anatomical locations, this development bodes very well indeed for manufacturers of imaging equipment that dodges the ionization bullet, a group that includes optical coherence tomography in addition to IVUS and other ultrasound modalities.
Whether payers are as ready to reimburse is another question, and an increasingly important one in this economy and in the fiscally massive future of Medicare, whose beneficiaries make up the majority of patients with both cardiovascular and peripheral vascular disease. According to a document published by Boston Scientific (Natick, Massachusetts), CMS pays substantially for IVUS for peripheral vascular applications on a hospital inpatient basis – as much as $7,900 for patients with major co-morbidities – but the payment tops out at only $115 for the procedure in a physician's office or ambulatory surgical center (ASC). However, the hospital inpatient code is good for the entire fiscal year whereas the physician office code expires March 1. The reimbursement code for ASCs is apparently in force for the 2010 calendar year.
Responding to a question posed by Medical Device Daily during a discussion, Rabih Chaer, MD, of the University of Pittsburgh School of Medicine (Pittsburgh), said physicians "try to minimize" the use of imaging that employs any kind of ionizing radiation, but added, "you have to do it at times." Chaer acknowledged that IVUS, a technology he discussed in his presentation, "can help minimize the exposure."
Mark Wholey, MD, an interventional radiologist with the UPP Radiology Clinic (Pittsburgh) was a bit more vocal about the physician's predicament. "I'm always concerned about the exposure" to patients, he said, but made the case that "physician exposure is becoming overwhelming."
"We have not paid attention" to the accumulated exposures experienced by physicians, Wholey continued, stating that in some months, "I've had my [recommended maximum] exposure for a year" in only 30 days.
PMT gaining wider acceptance
Chaer's presentation offered an overview of the current standards for treatment of DVTs as well as a few things now on the horizon. Six million people develop DVTs annually, he said, adding that "5% of the Medicare population has or will develop" a DVT. Complications include the notorious and potentially lethal pulmonary embolism, a big factor in the mortality rate of DVTs, which is said to be as high as 50%. Phlegmasia, a severe form of edema related to poor venous drainage, is also a risk, Chaer remarked, although less than 10% of DVTs incur this condition.
"Up to 95% of patients with ileofemoral" DVTs, those affecting the veins in the proximity of the upper leg and the hip bone, "have ambulatory venous hypertension at five years," Chaer said, adding that the concomitant development of varicosities is an issue, as is ulceration. The standard of care involves the use of anticoagulation drugs, which cuts down on embolisms and is easy to administer, but the ever-present bleeding issue persists, and anticoagulation apparently does not deal effectively with damage to blood vessels.
Persistent venous obstruction leads to valvular compromise as well, a state of affairs that prompts physicians to undertake mechanical, surgical and other removals of the offending mass. Catheter-directed thrombolysis shows an 85% success rate in clearing out the blockage in the upper femoral anatomy, Chaer said, adding that while intracranial bleeding is associated with this procedure, this outcome is "not common at all." At least 60% who undergo a catheter-based procedure are thrombosis-free and alive at one year, and quality-of-life scores are better than for pharmacological therapy alone.
All the same, physicians continue to gravitate toward pharmaco-mechanical thrombolysis (PMT), which is the subject of guidelines published in 2008 by the American College of Chest Physicians (ACCP; Northbrook, Illinois) for patients with acute DVT (Medical Device Daily, Sept. 17, 2008). This technique, like catheter-based therapies, "allows delivery of lytic agents" directly to the thrombus and "not only does it dissolve the clot, but aspirates" the clot as well, Chaer observed. "The ICU stay is non-existent", he remarked, adding that the "overall hospital stay can be minimized." He also made note of another important feature of this technology, namely "immediate symptom resolution."
Despite his enthusiasm, Chaer acknowledged that much is unknown about this approach, including which patients are and are not candidates for this procedure. He said that when the Acute Venous Thrombosis: Thrombus Removal With Adjunctive Catheter-Directed Thrombolysis (ATTRACT) trial is completed, "we will have a better grip on which treatment algorithm is better for which patient." However, this study, according to Clinicaltrials.gov, commenced enrollment only this past November and will not be finished until 2015.
The objective of the ATTRACT study, which is funded largely by the National Institutes of Health, is to randomize almost 700 patients into two arms across 40 study sites, with controls getting the conventional drug regime along with compression stockings. The other arm of the study will offer patients either catheter-delivered anti-thrombolytic drugs or one of two pharmaco-mechanical instruments, the Trellis, made by Bacchus Vascular (Santa Clara, California) and the Angiojet,(made by Medrad Interventional and Possis Medical (both Minneapolis). All the patients in this arm will receive Activase (alteplase), a tissue-plasminogen activator made by Genentech (South San Francisco, California).
The Trellis positions a pair of balloons on the outside of the thrombus and torques a wire in between to impart mechanical energy on the clot, thus breaking up the bulk of the thrombus, while the Angiojet uses jets of saline solution to loosen the thrombus. In both instances, the remains of the clot are vacuumed out via the catheter. The potential Medicare market for these DVT busters is, based on Chaer's estimate of 5%, is roughly 4 million of the Baby Boom population over the next few decades. However, DVTs are not exactly rare in middle aged Americans, and both items can be used in other anatomical locations as well.
Mark McCarty, 703-268-5690