NEW ORLEANS — Passive ventricular restraint achieved via a surgically implanted mesh bag fitted around the heart constitutes a novel and effective therapy for systolic heart failure, Douglas L. Mann, M.D., said at the annual scientific sessions of the American Heart Association.
Results of a 300-patient multicenter, randomized trial of Acorn Cardiovascular's investigational CorCap cardiac support device (CSD) showed that it improves left ventricular size and shape and enhances patient quality of life, said Dr. Mann, professor of medicine at Baylor University, Houston.
On the basis of the favorable results of this pivotal trial, in which Dr. Mann served as principal investigator, Acorn plans to petition the Food and Drug Administration for marketing approval in the first quarter of this year.
“This is a breakthrough technology,” he said.
He explained that the device provides gentle diastolic support for the heart, encouraging it to return from a dysfunctional spherical shape to a more mechanically efficient and electrically stable elliptical one. It is the first treatment specifically targeting the progressive ventricular enlargement that traditionally has been viewed as a symptom of worsening heart failure (HF) and that only recently has emerged as a therapeutic target in its own right. The degree of improvement in ventricular size and shape with use of the CSD dwarfs that seen in earlier trials of ACE inhibitors, β-blockers, and biventricular pacing, Dr. Mann added.
All participants in the Acorn study were on optimal drug therapy for HF; 81% were New York Heart Association class III. The 193 patients in whom mitral valve repair or replacement was indicated were randomized to undergo surgery with or without CSD placement. The remaining 107 patients were randomized to continued medical therapy alone or to undergo a thoracotomy for placement of the Acorn device, a proprietary synthetic mesh weave.
The primary study end point was a clinical composite of death, change in NYHA class, or need for a major cardiac procedure indicative of disease progression, such as transplantation or implantation of a left ventricular assist device. By these criteria, 37% of CSD-treated patients were blindly rated as worsened after a median 23-month follow-up, significantly less than the 45% rate among controls. Similarly, 38% of CSD-treated patients were judged improved, compared with 27% of controls.
CSD-treated patients showed dramatic improvements in left ventricular structure by three separate indices: reduced end-diastolic volume, reduced end-systolic volume, and a reduced sphericity index indicative of a return to an elliptical ventricle shape. The progressive improvement on these indices over the course of time suggested the mesh sack was encouraging functional unloading of the ventricle and reversing the natural history of the disease, Dr. Mann said.
Patients who received the Acorn device also demonstrated significant quality-of-life improvements on two measures: Minnesota Living With Heart Failure Questionnaire score and the physical functioning domain of the Short Form-36. Moreover, the device group required 19 transplants and other major cardiac procedures, compared with 33 in the control arm.
The benefits of the CSD have been sustained in patients who received theirs up to 4 years ago in the earliest nonrandomized safety studies. No evidence of pericardial constriction has been seen in a total of 540 patient-years of experience.
Dr. Mann estimated 40%-50% of the nation's 2.5 million patients with systolic HF would be candidates for the Acorn device. Many are also candidates for cardiac resynchronization therapy via biventricular pacing, which entails a far less invasive implantation procedure. But 20%-30% of HF patients who receive biventricular pacing are unresponsive to it, and among patients who do experience marked symptomatic improvement, the benefits often begin to fade after about a year.
Somewhat more measured enthusiasm for the device and its potential role was offered by discussant Bruce R. Rosengard, M.D., the British Heart Society Professor of Cardiac Surgery at University of Cambridge.
Although the CorCap is clearly safe and it does reduce ventricular size, the overall clinical improvement seen in the trial was “modest,” he said, noting the device did not improve mortality, NYHA class, or the number or duration of hospitalizations.
“Looking forward, if the procedure is to be carried out as stand-alone therapy, it would be optimal if less invasive surgical approaches could be developed,” he added.
“Where does it fit into current management of heart failure? If the study results are durable, and with additional follow-up, passive ventricular restraint would appear to have a useful role in patients with worsening heart failure despite maximal medical therapy and biventricular pacing,” Dr. Rosengard continued.
Particularly telling will be the subgroup analysis involving the two-thirds of study participants who underwent mitral valve surgery, which will be completed soon, he said.