Medical Device Daily Washington Editor
SAN FRANCISCO — This year's edition of Transcatheter Cardiovascular Therapeutics, or TCT 2009, includes the usual battles over how drug-eluting stents (DES) stack up against bare-metal stents (BMS) and against coronary artery bypass grafts (CABG), with Alberto Camenzind, MD, again leading the charge as he did three years ago in Barcelona at the annual meeting of the European Society of Cardiology (Sophia Antipolis, France).
Providing fresh fuel for the DES conflagration are updates for a raft of studies providing longer-term data than was previously available, but there are distractions to be found at TCT. Numerous device makers are on hand to make the case for their latest developmental products, including several designed to deal with heart failure associated with hypertension, and not all of those devices fall into the mold of traditional electrophysiology devices.
As for the Great DES Debate, one study that has made a huge splash recently is the Syntax trial, which generated one-year data that did the study's sponsor, Boston Scientific (Natick, Massachusetts) no favors. After one year, patients with left main and/or multi-vessel disease who opted for CABG fared better overall than those who chose angioplasty and the sponsor's Taxus DES, but two-year data suggest that the gap closes significantly between 12 and 24 months (Medical Device Daily, Sept. 4, 2009).
Another study poised to shape the DES debate – albeit the DES v. BMS debate – is the compilation of data from the registry operated in part by the American College of Cardiology (ACC; Washington), the National Cardiovascular Data Registry (NCDR). In an update published last week in the Journal of the American College of Cardiology, Pamela Douglas, MD, et al, combed through 30-month Medicare records for more than 260,000 patients and determined that death rates were down significantly in patients who chose DES rather than BMS (12.9% vs 17.9% unadjusted), as was the case with infarction (7.3 out of 100 patients against 10.0 in the BMS group).
The registry data, collected from patients undergoing intervention in the three years commencing Jan. 1, 2004, also showed a very slight elevation in revascularization (23.5 of 100 vs 23.4 in the BMS group), but the authors hypothesize that the seemingly high rate of revascularization in both groups may be affected by a failure of data to distinguish between target-vessel revascularization and revascularization of another anatomical location. Perhaps the most unexpected finding from the ACC-NCDR registry data is an insignificant difference in bleeding events between the two classes of stents despite the use of clopidogrel in the DES group.
Providing fuel for a different bonfire is the MADIT-CRT (Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchroniziation Therapy), which was covered in the Sept.1 edition of the New England Journal of Medicine. This trial deals with concomitant atrial defibrillation and ventricular resynchronization for patients with New York Heart Association class I and II heart failure, a controversial population where payers are concerned thanks to the inability of physicians to stratify patients in NYHA class III and IV for risk of sudden cardiac death (SCD). The prospect of SCD in atrial fibrillation patients has resulted in what some see as gross overuse of ICDs, a notion supported at least somewhat by data suggesting that fewer than four in 10 patients getting ICDs ever need defibrillating.
In the NEJM review, Arthur Moss, MD, et al state that data from an average follow-up of 2.4 years indicate that for those in this group who exhibit an ejection fraction of 30% or less and a QRS interval persisting for 130 milliseconds or longer, death or non-fatal heart failure was less prevalent in the study arm versus those who were only defibrillated. This primary endpoint appeared in slightly more than 17% of patients in the study group versus a bit more than 25% of controls.
However, most of the difference in this composite endpoint was generated by a reduction in heart failure of 41% in the study group compared to controls while the difference in death was negligible. Most of this benefit was found in patients whose QSR intervals stretched out over at least 150 milliseconds.
Physicians interested in reducing the risk of infarcts in their patients undergoing percutaneous interventions will no doubt flock to a session dealing with the use of bivalirudin (Angiomax) as a substitute for heparin plus glycoprotein inhibitors.
Covered last year in NEJM, the Horizons-AMI (Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction) trial, led by Greg Stone, MD, demonstrated that bivalirudin reduces 30-day adverse events (9.2% vs 12.1% for the control group) largely due to a reduction in bleeding events. Patients in the study arm were more likely to experience stent thrombosis over the first 24 hours post-procedure, but this difference disappears by 30 days.
The latest data from this study, covered in the Aug. 30 edition of Lancet, suggest that the benefits are not phantoms. One-year data indicate that patients getting bivalirudin experienced a statistically significant lower rate of bleeding (5.8% versus 9.2% getting the heparin/glycoprotein). Major adverse clinical events were a tie at 11.9%, but both cardiac mortality (2.1% versus 3.8%) and all-cause mortality (3.5% versus 4.8%) gave the nod to the study article.
Among those presenting study data this week to support their devices is Rob Kieval of CVRx (Minneapolis), which is working toward a PMA for the Rheos, a device that electrically stimulates baroreceptors located in the portion of the carotid arteries located in the neck with the intent of reducing blood pressure as prophylaxis for several conditions, including congestive heart failure and coronary artery disease.
Recently appearing in the literature in support of the hypothesis is the phase II study dubbed the DEBut-HT (Device-Based Therapy in Hypertension) trial, conducted in Germany and enrolling 21 patients who were refractory for pharmacological treatment and followed for three months.
The results, published in the July 20 edition of Hypertension (published by the American Heart Association, Dallas), were an average drop in blood pressure from 185/109 to 154/95 and a reduction in heart rate from 81 to 76 beats per minute. However, the authors recommended that the link between congestive heart failure and the reduction in heart rate and blood pressure "be investigated in further studies." CVRx is currently enrolling in the pivotal trial for FDA approval.
Mark McCarty, 703-966-3694;