Cutting-Edge Clinical Research Presented at TCT 2013

There were over 11,500 attendees at TCT 2013. This year, 1,750 abstracts were submitted from 56 countries and 39 U.S. states. Reviewers narrowed that number down to 851—a 49% acceptance rate.

The annual Transcatheter Cardiovascular Therapeutics (TCT) scientific symposium is the world’s preeminent forum for interventional cardiologists, cardiac surgeons, and vascular medicine specialists.

TCT celebrated a milestone 25 years at the 2013 meeting held in San Francisco, California. Attracting over 11,500 attendees, the symposium broke new ground by distributing tablet computers to attendees and producing an innovative digital app, enabling attendees to interact with sessions like never before and substantially reducing the need for printed materials. Highlights from the scientific sessions included:

New TAVR Options on the Horizon:

The pivotal CoreValve Extreme Risk trial found that transcatheter aortic valve replacement (TAVR) with the CoreValve device substantially reduced the incidence of death and major stroke at 1 year in US patients with severe aortic blockages considered too high risk to undergo surgery. An expanded study is ongoing and has enrolled nearly double the number of patients included in the current research.

Further, the REPRISE II trial tested the safety of a second-generation TAVR device internationally. The Lotus Valve System was associated with low rates of complications in symptomatic patients with severe aortic blockages who were at high risk for surgery. Successful implantation and positioning of the valve was achieved in all patients.

High Prospects for Third-Generation DES

Safety and effectiveness of new stents were tested in two studies. The SORT-OUT VI trial compared a stent with a permanent polymer coating and a stent with a biodegradable coating that releases the drug biolimus in Scandinavian patients. Both stents were associated with low rates of major cardiovascular complications 12 months after angioplasty.

The DUTCH PEERS (TWENTE II) trial was the first to compare the safety and effectiveness of third-generation drug-eluting stents. Both the Resolute Integrity zotarolimus-eluting stent and the Promus Element everolimus-eluting stent performed well with no differences in a study of nearly 2,000 patients. The third-generation stents release the same drugs as second-generation DES, but involve novel stent platforms with more flexible designs. The trial was simultaneously published in The Lancet.

Support for Short-Term Dual Therapy

Results of two studies provided further evidence that shorter-term dual antiplatelet therapy, or DAPT, lasting 3 months after stenting may be safe, while prolonged therapy beyond 1 year may be harmful. OPTIMIZE showed the noninferiority of 3-month DAPT to standard 12-month therapy after implantation of the Endeavor stent. Importantly, short-term DAPT did not increase the risk of dangerous blood clots that can form inside the stent, known as stent thrombosis. Results of the OPITMIZE trial were also published in the Journal of the American Medical Association.

In the ARCTIC-INTERRUPTION trial, no benefit was noted and greater risk of bleeding was seen when DAPT was continued beyond 12 months. The study was the second half of the randomized ARCTIC trial, which tested adjustment of antiplatelet therapy based on platelet function testing. At 1 year after stenting, roughly half of the original randomized cohort, who were at lower risk than the overall population, were randomly assigned to either stop DAPT or continue it for up to 18 months. At follow-up, there was no difference in complication rates. However, those who discontinued DAPT experienced less bleeding.

Two Stents for Bifurcation Lesions?

Treating coronary blockages that have split into two branches, also known as bifurcation lesions, has proven difficult and two studies examined the outcomes associated with using a two-stent treatment approach compared with traditional single stenting plus using an additional stent when necessary. In NORDIC-BALTIC BIFURCATION IV, rates of major complications at 6 months were comparable between treatment options.

The Tryton Bifurcation study failed to show noninferiority of the two-stent strategy compared with single-stenting plus an additional stent when necessary. However, it did find that the new technique was better than provisional stenting at widening the side branch, or the secondary branch of the lesion, at 9 months.

Angioplasty Best Practices

The CHAMPION PHOENIX trial explored the relationship between stent thrombosis that occurs during angioplasty and short-term complications. While a small percent of patients develop stent thrombosis during angioplasty, the study found that it carries serious implications for patients, as it is related to longer hospital stays. Importantly, use of the antiplatelet drug cangrelor was found to help prevent intraprocedural stent thrombosis.

Performing angioplasty via an artery in the wrist (radial) as opposed to the groin (femoral) is reasonable and may be preferable in women, according to results from the SAFE-PCI for Women study. There was a substantial reduction in complications with the radial approach, and it resulted in lower volumes of contrast dye being used. In addition, radial access was preferred by the majority of women.

A subgroup analysis from the FREEDOM trial of diabetic patients assigned to either open-heart surgery or angioplasty with a first-generation drug-eluting stent found higher rates of major complications at 5 years among those treated with insulin. However, the differences in clinical outcomes between surgery and angioplasty were maintained regardless of the presence or absence of insulin treatment. Stroke rates were higher among patients assigned to surgery regardless of insulin use.

The SMART-CASE randomized trial found that in patients with intermediate coronary blockages, a conservative approach to determining appropriateness of angioplasty is safe and equivalent to an aggressive approach. At 1-year follow-up, both strategies exhibited comparable rates of adverse events

Revascularization Techniques Scrutinized

The first randomized pilot study of a new revascularization technique that combines minimally invasive bypass surgery with angioplasty is safe and feasible in select patients with multivessel heart disease, according to results from the HYBRID trial. The vast majority of patients who underwent the hybrid procedure received complete revascularization, with a small percentage requiring conversion to open surgery. Complications at 1 year did not differ between study groups, and there was no incidence of stroke in either group. Future analyses plan to address quality of life and cost-effectiveness of the hybrid procedure.

In TATORT-NSTEMI, aspiration thrombectomy, or using a device to “suck out” coronary blockages, failed to reduce the extent of microvascular obstruction or improve outcomes compared with standard coronary angioplasty alone in less severe heart attack patients. This lack of benefit was consistent across subgroups and blockage size and blood flow level. At 6 months, patients showed similar complication rates regardless of whether they did or did not receive thrombectomy with angioplasty.

Diagnostic Tools Improve Upon FFR

Two studies explored novel strategies of accurately assessing inadequate blood flow compared with a method called fractional flow reserve, or FFR. For HeartFlowNXT, FFR derived from computed CT scans (FFRCT) was compared with coronary CT angiography and invasive FFR alone. Per-patient diagnostic performance was better with FFRCT compared with the other two methods without sacrificing specificity.

ADVISE II was a global study that compared traditional FFR with instantaneous wave-free ratio (iFR), which does not require the administration of the drug adenosine. In the study, iFR performed well with regard to the percentage of coronary blockages properly classified by hemodynamic severity. A hybrid iFR/FFR approach also appropriately classified the vast majority of blockages.

Encouraging Results for Drug-Coated Balloons

Two trials showed encouraging results for drug-coated balloons in patients with diseased arteries in the legs. Six-month findings from the LEVANT 2 trial comparing an investigational paclitaxel-coated balloon with standard balloon angioplasty at 55 global sites showed advantages to the drug-coated balloon. Safety outcomes were similar between the two treatment groups.

Similarly, the multicenter, prospective, randomized RIBS V trial compared the use of DES and drug-coated balloons in treating vessel re-narrowing after stenting. Patients with bare metal stents received either the Xience Prime everolimus-eluting stent or SeQuent Please paclitaxel-coated balloon. At 1 year follow-up, the stent was slightly more effective, but both techniques yielded similarly positive outcomes.

Treatment Additions for STEMI Patients Explored

Results from CHILL-MI indicate that in patients who have suffered the most serious form of a heart attack known as STEMI, rapid cooling prior to restoring blood flow is safe and feasible. Patients were randomly assigned to standard of care or hypothermia induced by cold saline and endovascular cooling. Cooling did not reduce infarct size in relation to heart tissue at risk in the allotted time. No patient died, but the incidence of clinical heart failure was lower in the hypothermia group.

Administering the antithrombin agent bivalirudin to STEMI patients during transport to the hospital reduces the risk of short-term death and major bleeding better than heparin plus optional use of a glycoprotein IIb/IIIa inhibitor, or GPI, according to results from the EUROMAX trial. No difference was seen between the two strategies for all-cause or heart-related death, although the trial was underpowered for these endpoints. Findings of the trial were also published in the New England Journal ofvcine

Inconsistent Results with Platelet Function Testing

TRANSLATE-POPS showed that routine blood platelet function testing with the VerifyNow P2Y12 test had only a modest impact on the amount of adjustment to antiplatelet therapy of patients with STEMI and non-STEMI heart attacks. Incidence of therapy adjustment before hospital discharge in the patients who received routine platelet function testing was higher than in those not undergoing such testing. The majority of adjustments manifested as drug switches, rather than adjustments in dose, and primarily involved switching from the standard blood-thinner clopidogrel to the newer agent prasugrel.

But in the GIANT trial, platelet function testing was helpful for optimizing antiplatelet therapy for individual patients tested within 48 hours of an acute heart attack and treated with a first-time angioplasty with stenting. Among slow responders to clopidogrel who were adjusted to optimal therapy based on platelet function testing, the occurrence of death, heart attack, and stent thrombosis at 1 year was similar to normal or high responders.

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