Medical Device Daily Executive Editor
ORLANDO — The game — and the language — concerning drug-eluting stent (DES) technology has clearly changed.
At the beginning of the century, as DES devices were being hyped, approved and then rolled out to the markets, they were bannered as being not just an improvement over bare-metal stents (BMS), but much better — even “game-changing,” “disruptive,” and promising huge advantage over their lowly, red-headed, precursor BMS cousins.
Today, however, DES more often is being offered to the medical community, and to patients, as “no worse” than BMS.
The “no worse” — a sort of “not to worry” message — was delivered during this week’s American Heart Association (AHA; Dallas) annual scientific sessions at the sprawling Orange County Convention Center by Laura Mauri, MD, of Brigham and Women’s Hospital and Harvard Medical School (both Boston), reporting on what she said was the largest-ever study comparing the long-term comparison of outcomes for patients implanted with either DES or BMS devices.
The study’s conclusion was that DES resulted in a reduction of revascularization procedures over BMS — which had been touted early-on as their major benefit; and that they do not produce a higher rate of mortality or myocardial infarction (MI) — allaying those suspicions which have resulted from a series of recent trials and experiential reports from physicians.
Overall, the result of the study, she said, was to provide “reassurance” concerning DES safety. And that is a whole different approach to describing the risk/benefit algorithm for the technology which supported broad initial DES uptake.
When Mauri was challenged concerning what “reassurance” this type of assessment provides to the manufacturers of DES devices, she told Medical Device Daily that she was very much attempting to be “cautious” in her wording, signaling her awareness concerning the debate that DES use has generated among cardiologists and their patients.
In her presentation and in Q&A follow-up, she emphasized the large size of the study, which looked at a cohort of 17,762 patients identified by means of a database that monitors the quality of cardiac care at non-U.S. government-operated hospitals in the state of Massachusetts.
About two-thirds were treated with DES, the remainder with BMS, with about 65% of the DES-implanted group receiving the sirolimus-eluting Cypher stent from Cordis (Miami Lakes, Florida).
Mortality risk differences were determined from vital statistics records of these patients, the study providing a look at two-year follow-up, and risk-adjusted mortality rates estimated using clinical information collected at patient admission.
The study made no attempt to compare the Cypher with the competing FDA-approved product, the Taxus from Boston Scientific (Natick, Massachusetts), Mauri said.
The unadjusted cumulative incidence of mortality at two years was 6.7% for DES and 12.4% for BMS (-5.7 % difference, and with a 95% confidence interval). Two-year risk-adjusted mortality rates were 9.4% for DES, 11.9% for BMS; MI rates 10.8% for DES, 11.8% for BMS; and revascularization rates 20.1% for DES, 23.9% for BMS.
While the study of this population — described by Marui as highly “robust” — was offered by her as serving to reduce fears concerning DES, another report related to the effects of DES-associated thrombosis was distinctly unsettling rather than reassuring.
A presentation by Ron Waksman, MD, associate director of the division of cardiology at Washington Hospital Center (Washington), indicated that the DES-associated category of thrombosis is a “highly morbid event.”
More specifically, he told MDD that DES-associated thrombus may result in a death rate of up to 50%.
When he was offered the possible comparative analogies of a person being run over by a rickshaw or run over by a locomotive, Waksman said DES-stent thrombosis clearly is the “locomotive” of adverse events.
The study universe was 7,920 patients DES-implanted and 215 of these patients suffered either confirmed “definite” thrombosis or “definite or probable” thrombosis. Both groups had high rates of heart failure, heart attacks and restenosis, tapering off the longer they were followed.
Given the 215-of-7,920 ratio, this was just one-quarter of 1% for DES-associated thrombosis, but Waksman and others on the panel said that this should not be taken as representing the ratio in real-life circumstances, that the data on thrombus reported varies widely from region to region and could range to 1% to 2% of DES implants.
A report that could be put back under the “reassuring” side of the stenting ledger was then offered by Waksman in discussing one-year follow-up of patients implanted with the resorbable stent from Biotronik (Berlin), though the name of the stent manufacturer was not revealed until Q&A following Waksman’s presentation.
PROGRESS-AMS (Absorbable Metal Stent), Waksman said, is a first-in-man study, with a one-year review, utilizing intravascular ultrasound to measure formation of new layers of inner wall growth (intima) in the stent and “deleterious” vascular remodeling.
At follow-up, none of the patients had died, had heart attacks or stent thrombosis.
In eight patients who underwent later ultrasound examination, the original stent didn’t shift and there was no evidence that the stent had remained in the vasculature.
Overall, the resorbable stent has been touted by the interventional community as solving the problems of DES in which a stent remaining in the body — or the drug, or the polymer used to fasten drug to stent — may be the source of thrombosis.
PROGRESS-AMS thus would appear to offer promise that this expectation may become reality.