Endovascular physicians and interventional cardiologists are overwhelmingly likely to use drug-eluting stents (DES) more often in the future because they believe their costs will decrease as competition among manufacturers increases. That's the consensus from a recent survey conducted by Transcatheter Cardiovascular Therapeutics' (TCT; New York) web site, www.tctmd.com. The findings come from TCT's survey of a subgroup of its global interventional cardiology users to determine the impact of DES on their clinical practices.
A large majority (88%) of the physicians surveyed said they expect drug-eluting stent usage to increase compared to the remaining 12% who expect such use to remain the same. None expect DES use to decrease in the future. Physicians will use drug-eluting stents more frequently due to a decrease in cost, according to the survey results. In fact, 93% of the physicians cited lower cost as the determining factor in using DES in the future. The respondents also attribute a growing supply and availability of drug-eluting stents, as well as an increasing diversity in size and length of the devices, as factors in increasing their use.
A total of 124 responses were received, according to TCT. A majority of the responses were from North America (61%), followed by Europe (18%) and Asia (11%). The remaining responses were from South America, the Middle East and Australia/New Zealand. A majority of the physicians who responded perform between 100 and 500 interventions yearly, with most performing between 200 and 300, TCT noted. A majority (51%) of the respondents use drug-eluting stents in fewer than 25% of patients. Roughly a fourth (24%) use them in 25% to 50% of cases, while 19% use such stents in 50% to 80% of cases, according to the results.
Physicians stated they would not use a drug-eluting stent in three situations. Some 70% said they would not use one if the appropriate size or length was not available. Second, 68% cited cost concerns for not using such stents. And 58% felt a drug-eluting stent is not needed in low-risk patients with low-risk lesions. When asked about any increase in complications from using a DES, several physicians said that the stents were more difficult to deliver and less trackable.
Independent reports support DES use
The assumption of superiority of drug-coated stents over bare-metal stents was underlined still further the week prior to this month's Transcatheter Cardiovascular Therapeutics conference with the release of two independent reports likely to raise the stock for this technology even further. One report came from the non-profit health research agency ECRI (Plymouth Meeting, Pennsylvania), the other from Hayes (Lansdale, Pennsylvania), which specializes in health technology assessment and tracking of new and emerging healthcare technologies.
In its report, "Drug-Eluting Stents for the Treatment of Coronary Artery Disease" one in its series of Windows on Medical Technology assessments ECRI evaluated trials for both sirolimus- and paclitaxel-coated stents, and concluded that the rate of restenosis for these stents "was as much as 64 times lower than that of bare-metal stents." The assessment looked at four trials, two each for the two types of drug coatings, with ECRI saying that "in general, all four studies were well-designed, high-quality trials." Issues covered in the study addressed effectiveness and safety in five areas of comparison: the risk of developing in-stent restenosis, the risk of recurrence of symptoms of angina, the number of redo treatments required, patient quality of life improvements and reduction in morbidity and mortality.
The report noted the higher cost of the drug-coated stents but said that this extra cost is likely to be counterbalanced in the minds of third-party payers by the "effectiveness in preventing the need for retreatment from restenosis."
Similar to ECRI's report, Hayes looked at studies of both the sirolimus-eluting and paclitaxel-eluting stents. The Hayes report concludes that Cordis's (Miami Lakes, Florida) Cypher stent "significantly reduces the likelihood of reblockage of the artery and consequently reduces the need for repeat coronary revascularization or other treatment, and improves event-free survival." And it went on to say that "early studies suggest that paclitaxel-eluting stents confer similar benefits as sirolimus-eluting stents for treating coronary artery disease."
Stem-cell technology: Cardiac tissue fix?
Stem cells can help cardiac tissue to repair itself weeks after a heart attack, new research being conducted at the Cleveland Clinic (Cleveland, Ohio) suggests. The study identified the first stem cell "homing factor" for cardiac muscle tissue, which allows stem cells to zero in on an area of tissue damage. The body's normal reparative process is short-lived, lasting only a few days following a heart attack. Complete research results were published in the Aug. 30 issue of The Lancet. Cleveland Clinic researchers identified stromal cell derived factor-1 (SDF-1) as the first stem cell homing factor for the heart. The organ naturally expresses the molecule following a heart attack; however, the molecule is not present long enough to lead to significant cardiac tissue regeneration in its current form. While these new findings are based on animal studies, the research holds promise in helping to battle one of man's leading killers.
In recent years, experimental models have suggested the possibility of stem-cell transplantation and endogenous stem-cell mobilization for treatment of congestive heart failure. "This study indicates that the body will work to heal itself if it has the right tools available," said study investigator Marc Penn, MD, PhD, staff cardiologist and clinical associate in cardiovascular medicine at the Cleveland Clinic. "Our job is to use this information to determine how to recreate the signals that orchestrate tissue regeneration to maximize the effectiveness of stem cell technology and improve lives," he told Cardiovascular Device Update.
Previous studies have indicated that damaged heart muscle could be regenerated by directly injecting stem cells into the bloodstream or by chemically mobilizing stem cells from bone marrow either prior to a heart attack or within 48 hours afterward. At the Cleveland Clinic, Penn and his colleagues looked at the potential of stem cells in repairing hearts weeks after a heart attack, in the presence of CHF. To determine whether SDF-1 was sufficient to induce stem cell homing and recovery of heart function, investigators transplanted cells that expressed SDF-1 into hearts eight weeks following a myocardial infarction. Their research showed that re-establishing SDF-1 expression in the heart led to the homing of circulating stem cells to the injured organ, the growth of new blood cells and the recovery of cardiac tissue.
Reintroducing SDF-1 to the heart yielded nearly a 90% increase in heart function compared to hearts treated with cells alone. Just increasing the number of circulating stem cells using drugs that induce stem-cell mobilization eight weeks after a heart attack was not enough to initiate meaningful tissue regeneration, supporting the notion that repair to the damaged tissue is possible for only a limited amount of time following the MI.
"I think the next step is to try and deliver the SDF-1 in a clinically viable strategy," Penn said. "The strategy that we are most comfortable with is combining cell and gene therapy where you use adenoviral vectors to transvect skeletal myoblasts."
Penn also said he believes that the SDF-1 could one day be placed on a stent in lieu of the more popular drugs of today to prevent restenosis. "You could imagine drug-eluting stents with SDF-1 or just a stent with SDF-1 expressing that would call endothelial progenitor cells to the site of vascular injury and it could theoretically be a therapy for restenosis as well," he said. While Penn and his colleagues are still working with animal models, he said he hopes to take the research to the clinical level within the next couple of years.
Risk scoring newest aid for AF
Now patients with new onset of atrial fibrillation can be scored to estimate the risk of stroke or death, which could lead to appropriate treatments being administered earlier, according to a new research study. The classification system, which appears in an August issue of the Journal of the American Medical Association (JAMA), was derived from a study supported by the National Heart, Lung, and Blood Institute and the National Institute of Neurological Disorders and Stroke, both affiliate organizations within the National Institutes of Health (Bethesda, Maryland). The research was conducted at the Framingham Heart Study (Framingham, Massachusetts) on 868 patients with new onset of atrial fibrillation (AF).
The research adds to a long list of previous clinical trials that either support anticoagulant therapy early to prevent future strokes or suggest restricting its use due to risks of bleeding. Surgical options have also been debated in treating these patients, due to risks of stroke during the procedure. AF patients have a five to six times higher chance of stroke, and its classification also known as risk stratification can assist physicians in determining the appropriate treatment. Some patients may benefit more from blood thinning medications while others may need immediate surgery.
"A risk score for stroke was derived that included the following risk predictors: advancing age, female sex, increasing systolic blood pressure, prior stroke or transient ischemic attack and diabetes," wrote Thomas Wang, MD, the lead researcher at Framingham Heart Study. "With the risk score, 14.3% of the cohort had a predicted five-year stroke rate of 7.5% or less (average annual rate 1.5% or less), and 30.6% of the cohort had a predicted five-year stroke rate of 10% or less (average annual rate 2% or less)."
Wang said, "These risk scores can be used to estimate the absolute risk of an adverse event in individuals diagnosed with AF, which may be helpful in counseling patients and in making treatment decisions." He added, "Our data indicate that although AF is associated with a high overall risk of stroke or death, risk factors can be used to easily stratify patients at particularly high or low risk."