ACC Scientific Session-i2 Summit 2011: The Devil Is in the Details

NEW ORLEANS, LA—New devices dominated the scene at this year’s American College of Cardiology Scientific Session/i2 Summit, held April 3-5, 2011. But fresh findings came from a variety of specialties, with interventionalists and surgeons alike hearing results that could fine-tune clinical practice.

Chair of the i2 Summit David J. Moliterno, MD, of the University of Kentucky (Lexington, KY), told TCTMD in an interview that a common theme of the week was that attention to detail matters and can make a difference in improving outcomes, whether for femoral-access PCI or for aortic valve repair.

PARTNER Takes the Lead

Dr. Moliterno highlighted late-breaking data from the PARTNER (Placement of AoRTic traNscatheterER valves) trial’s cohort A analysis, which was featured in the conference’s opening session. “The reason why it was given a showcase spot was to pull together noninterventional cardiologists and interventional cardiologists,” he said. “We believe that this aspect of cardiology really spans the gap from general cardiology to imaging, interventional cardiology, and surgery.”

The new findings show that, in high-risk patients with aortic stenosis who are considered eligible for surgery, transcatheter aortic valve implantation (TAVI) matches surgical valve repair at 1 year, with mortality rates of 24.2% and 26.8%, respectively (P = 0.001 for noninferiority). Although the rate of stroke/transient ischemic attack remained higher with TAVI at 8.3% vs. 4.3% with surgery (P = 0.04), Dr. Moliterno pointed out that this represented an improvement in the results from PARTNER’s cohort B, which evaluated TAVI vs. standard therapy in inoperable patients.

“A lot of people said they had some reticence or concern about the strokes in the TAVI group, and that’s very understandable. What encourages me though is that if we look from PARTNER B to PARTNER A, a similar risk cohort, the strokes were already 35% lower. So I’m hoping, with even more experience and a newer generation device, that number will continue to decrease,” he said, attributing much of the success to the study’s team-based treatment approach.

The much anticipated results suggest that TAVI may be suitable for a wider patient population than previously shown, Dr. Moliterno added. Up to 150,000 aortic valve surgeries are performed every year in the United States, he said, so if TAVI becomes accepted as an alternative to surgery in increasingly lower-risk patients, many could undergo the treatment.

Another presentation of PARTNER data showed that the cost of TAVI falls well within the acceptable range for cardiovascular therapies.

Femoral Stands up to Radial Access

The RIVAL (RadIal Vs. femorAL) trial was another milestone of the week, Dr. Moliterno noted. The largest randomized trial to compare transradial and transfemoral access, RIVAL demonstrated that while the 2 approaches show similar overall safety and effectiveness, the radial approach for angiography and PCI yields lower vascular complications and may be preferred at high-volume centers and for STEMI.

“Many of the post hoc analyses and registries have shown radial arterial procedures to be associated with a markedly lower rate of adverse events, such as mortality and certainly major bleeding,” he said.

In contrast, RIVAL is encouraging in that it showed fairly equivalent results with both radial and femoral access in such a large cohort, Dr. Moliterno said. “We had a study of 7,000 patients and couldn’t find a difference, so how much bigger are we going to need to go before we might find a difference? [Concern about femoral access] might not be fully laid to rest, but I think people are encouraged that it may not be so worrisome.”

MACE rates for both techniques “were particularly low,” perhaps because investigators were paying more attention than usual, Dr. Moliterno noted. But the similarity between radial and femoral access should not deter expanding use of radial access in the United States, he added. “There are certainly conveniences. And in the RIVAL study, patient preference was towards radial artery access. . . . Patient preference is important. We do want patients to be happy and to have a procedure that they not only literally but also figuratively feel comfortable with.”

New Devices Make Their Case

Other interesting findings came from studies of novel stents, Dr. Moliterno noted.

The PLATINUM trial found that an everolimus-eluting stent with a novel platinum chromium-alloy platform, known as Promus Element (Boston Scientific, Natick, MA), is clinically noninferior to the currently available Xience V/Promus stent that releases the same drug from a cobalt chromium platform. At 12 months, a per protocol analysis found that the rate of TLF (primary endpoint; composite of target vessel-related cardiac death, target vessel-related MI, or ischemia-driven TLR) was 2.9% with the cobalt chromium stent and 3.4% with the platinum chromium stent (P = 0.001 for noninferiority).

Among the reasons why the new stent is being studied, Dr. Moliterno said, are its improved deliverability and visibility. “The platinum-based material could be more easily seen radiographically. Remember, this generation of stent has thinner struts, so they’re less obvious angiographically. They’re a bit hard to see. One of the concerns with these stents that are so radiolucent is that it’s hard to get the positioning accurate,” he explained.

The RESOLUTE US trial, meanwhile, compared results from the novel zotarolimus-eluting Resolute stent (Medtronic, Santa Rosa, CA) with those of Medtronic’s Endeavor stent in patients with de novo native coronary lesions. The 2 devices are largely similar with the exception of Resolute’s hydrophilic polymer, which extends drug elution time by as much as 6 months. At 12-month follow-up, the primary endpoint of TLF (composite of cardiac death, MI, and clinically-driven TLR) was 3.7% for Resolute and 6.5% for historical controls (P < 0.001 for noninferiority).

And in the ABSORB trial, a second-generation fully bioabsorbable DES, known as BVS (Bioabsorbable eVerolimus-eluting Stent; Abbott Vascular, Santa Clara, CA), showed 1-year clinical and angiographic outcomes similar to those achieved with current DES, demonstrating the promise of this intriguing technology. The stent has a backbone of poly-L-lactic acid that provides support and a coating of poly-DL-lactic acid that contains and controls the release of everolimus. All components of the BVS, except for 2 radio-opaque markers, are expected to fully absorb into the human body within 2 years.

In the burgeoning field of percutaneous valves, 2-year results from the EVEREST II trial showed that percutaneous mitral valve repair with the MitraClip device is a durable option for patients with moderate to severe mitral regurgitation (MR), but offers less effective MR reduction compared with surgical treatment. At 2 years, 1 in 5 percutaneously-treated patients required surgical valve repair or replacement, with most needing surgery in the 6 months following insertion of the clip.

Fine Tuning Treatment

Dr. Moliterno also praised the EXCELLENT trial, 1 of several studies from South Korea in recent years to examine the optimal duration of dual antiplatelet therapy after DES. In the current study, patients implanted with either everolimus- or sirolimus-eluting stents experienced similar clinical outcomes whether they received 6 or 12 months of dual antiplatelet therapy. The 1-year rate of TVF (composite of cardiac death, MI, or TVR) was 4.7% with a 6-month regimen and 4.4% with a 12-month regimen (P = 0.721), although patients with diabetes appeared to benefit from longer treatment.

EXCELLENT “is probably too small to give us full confidence, . . . but again it’s another signal that shorter therapy with the current generation of drug-eluting stents is highly likely to be acceptable. It is great news and very encouraging for us,” he said.

The Nordic Bifurcation study, meanwhile, showed that complex bifurcation lesions can be adequately treated by a strategy of stenting only the main vessel and sparing the side branch unless necessary. The approach is just as effective as the more complex approach of routinely stenting both branches. MACE-free survival at 5 years was similar in the single- and double-stent groups (85.5% vs. 80.1%; P = 0.16).

Another study, REMEDIAL II, looked at whether using a closed-loop fluid management system (RenalGuard, PLC Medical Systems, Franklin, MA) combined with low-dose furosemide could effectively reduce contrast-induced nephropathy (CIN) in high-risk patients. Study participants undergoing elective catheterization were randomly assigned to receive either conventional hydration with a combination of N-acetylcysteine (NAC) and sodium bicarbonate solution or hydration with normal saline plus NAC and low-dose furosemide (0.25 mg/kg) controlled by the RenalGuard system.

The new treatment resulted in a significantly lower CIN incidence at 48 hours compared with conventional hydration (11.0% vs. 20.5%; P = 0.25).

Not all attempts at improvement were successful, however. The phase IIb PROTECTION-AMI trial, for example, found that a novel drug that inhibits delta-protein kinase C, an enzyme that has been tied to reperfusion injury, failed to reduce infarct size in PCI patients.

Studies Take on Surgery

Several trials related to surgery also held center stage at the conference.

The PRECOMBAT study found that PCI with Cypher sirolimus-eluting stents (Cordis, Miami Lakes, FL) and CABG were associated with similar rates of MACCE (death from any cause, MI, stroke, or ischemia-driven TVR) at 1 year  in patients with unprotected left main disease at 8.7% and 6.7%, respectively (P = 0.001 for noninferiority). However, investigators cautioned that the noninferiority margins were too wide for the findings to be considered definitive.

ISAR-CABG, on the other hand, provided good news for interventional cardiologists. In high-risk saphenous vein graft lesions, DES cut TLR rates almost in half from 13.1% to 7.2%, leading to an overall decrease in late outcomes.

Two iterations of the STICH (Surgical Treatment for Ischemic Heart Failure) trial delivered less clear-cut results. The study’s main intention-to-treat analysis found that adding CABG to medical therapy does not reduce all-cause mortality in patients with left ventricular dysfunction over long-term follow-up (36% with CABG and 41% with medical therapy alone; P = 0.12), although results from a per protocol analysis suggest that CABG may help improve survival. A separate subanalysis of the trial, meanwhile, showed that the presence of viable myocardium did not increase survival or help differentiate which patients might benefit from surgical intervention.

 


Sources:
Presentations at: American College of Cardiology Annual Scientific Session/i2 Summit; April 3-5, 2011; New Orleans, LA.

 

 

Related Stories:

Disclosures
  • Dr. Moliterno reports receiving consulting fees/honoraria from Boston Scientific, Merck/Schering-Plough, and Symetis.

Comments