Over the next three days, a voluminous amount of data will be presented, shared, and debated among an estimated 18,000 attendees of the annual meeting of the American College of Cardiology, this year held in Washington, DC.
While the meeting covers the whole spectrum of cardiology and heart-related issues, there are a number of studies and late breaking clinical trials specific to the subspecialty of interventional cardiology.
Starting on Friday morning, March 17, we’ll get the results from SURTAVI, an important clinical trial testing Medtronic’s CoreValve self-expanding transcatheter aortic valve in patients at intermediate risk for surgery. The PARTNER II trial studied these patients when implanted with Edwards’ Sapien3 device. Based on these results, Edwards’ TAVR prosthesis gained FDA approval in August of last year for use in patients at intermediate risk for surgery. The results of the SURTAVI study will form the basis for an anticipated FDA approval of the CoreValve for implantation in this patient population.
On Saturday, three Late-Breakers involving physiologic guidance will be presented. This field comprises FFR and iFR modalities which measure the specific ischemic impact of a coronary blockage, as opposed to visual assessment, guided by angiography. The DEFER, FAME and FAME II trials established that the physiologic measurement (Fractional Flow Reserve or FFR) of suspect lesions targeted those blockages that would benefit from intervention/angioplasty more accurately than visual angiography alone. The results of these studies were that the amount of stents placed could be reduced by a third, and the clinical outcomes would be improved, also by a third.
COMPARE-ACUTE: This study looked at a little under 1,000 patients who presented with STEMI, the most significant type of acute heart attack. When treating a STEMI case with angioplasty, the culprit lesion is always dilated and stented, stopping the heart attack in its tracks. But what if there are other blockages in the same or other coronary arteries? There has been much debate over whether to perform a complete total revascularization, stenting all blockages, during the same procedure, or whether to stage these interventions and treat the non-culprit lesions at a later date. COMPARE-ACUTE will measure outcomes when FFR is used to determine whether or not to stent a non-culprit lesion in the initial procedure. If the FFR strategy shows significantly better outcomes, this study may change clinical practice.
Two of these new studies incorporate a different modality: iFR or Instantaneous Free-Wave Ratio, which has the advantage of not requiring the hyperemic agent adenosine. Since its appearance, the question of whether iFR is as accurate a measure as FFR, especially in intermediate blockages, has been the subject of heated debates at many cardiology meetings. Saturday’s presentations will include two studies with almost 5,000 patients enrolled, and will, to a great extent, answer the question of whether iFR is non-inferior to FFR in assessing the need to stent a blockage. The iFR technology is proprietary and was developed by Volcano Corporation, now part of Philips Image Guided Therapy, so there is a lot riding on these studies for Philips. Regardless of the outcomes for iFR, these two studies represent the largest patient cohort to date for studies assessing physiological monitoring and should advance that modality in clinical practice, guidelines, and reimbursement.
First is DEFINE-FLAIR, described as a multi-center (over 50 hospitals worldwide with 2,500 patients) prospective, randomized, blinded comparison of clinical outcomes and cost efficiencies of iFR and FFR decision-making for physiological-guided coronary revascularization.
Second is IFR-SWEDEHEART, which is similar in design to DEFINE-FLAIR, except that it only enrolled patients in Sweden. But the patients number around 2,000. Should the outcomes of these two studies show a consistent positive outcome for iFR, its reliability would be given a major boost.
DECISION CTO: This Korean study looks at whether opening up a chronic total occlusion (CTO) with a drug-eluting stent is better than not attempting to revascularize that total blockage at all and just treating the patient with optimal medical therapy. Over 1,000 patients have been enrolled.
And then there is a trial many have been anticipating, the two-year outcomes from ABSORB III, measuring the results of Abbott’s Bioresorbable Vascular Scaffold (BVS) vs. the company’s standard second-generation DES, the Xience. At the 2015 TCT meeting, there were many concerns over the one-year results, which showed a doubled incidence of stent thrombosis with the Absorb. Subsequent analyses of these data revealed that this increase occurred primarily in narrower vessels, less than 2.5mm in diameter, so when the FDA approved the Absorb BVS, it was with the caveat that it not be used in these arteries. Of course, as time goes on, the BVS is supposed to degrade and disappear. So it will be important to see whether the rates of stent thrombosis or other negative outcomes do not increase.
The ACC is also including a number of featured research presentations, several concerning TAVR/TAVI devices in comparison to surgically implanted valves. Stay tuned to Angioplasty.Org and follow us on Twitter for the latest news out of ACC.17.