SEATTLE – A tiny pump that provides partial support to patients with heart failure may improve outcomes, at least in the short term, for those in the earlier stages of the disease, clinical experience with the device has shown.
The 20 patients in Belgium and Germany who underwent implantation of the newest version of the investigational device had significantly improved hemodynamics, exercise tolerance, and end organ function at a median of 12 weeks’ follow-up, Dr. Daniel Burkhoff reported at the annual meeting of the Heart Failure Society of America.
The rate of adverse events was about 10 per patient-year in the first month after implantation and roughly 3 per patient-year thereafter.
The findings suggest that "significant and sustained improvements in hemodynamics, exercise capacity, and quality of life can be achieved in this population," commented Dr. Burkhoff of Columbia University in New York and also medical director of CircuLite.
The micropump (known as the Synergy System and manufactured by CircuLite in Saddle Brook, N.J.) received the CE mark for use in Europe in September.
Discussant Dr. Robert L. Kormos of the University of Pittsburgh Medical Center maintained that longer-term data will be needed to assess true sustainability of the results. He also questioned whether the 20 patients described were similar clinically to the entire group of 58 patients who have received some version of the device.
It’s unclear at this point if a U.S. trial designed for Food and Drug Administration approval will focus on a combined heart failure indication versus that of a separate indication as a bridge to transplant or destination therapy, he said.
"The trial suggested that a major reduction in adverse events compared to those seen with contemporary LVADs [left ventricular assist devices] can be achieved through the strategy of early implantation in the spectrum of heart failure and the minimally invasive approach that was used," Dr. Kormos commented. However, the relative contributions of patient selection and the device to this favorable outcome were unclear, he added.
"I do consider this in many respects a landmark [study]. This opens a window to a new therapy that many of us, especially as surgeons, are looking forward to, specifically because it allows us to operate on a group of patients who have fewer comorbidities than we currently see," he concluded.
The patients in the study had heart failure with Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) 4 or higher disease, corresponding to New York Heart Association class III or IV, and were symptomatic despite appropriate medical therapy and cardiac resynchronization therapy. They were ambulatory, were not dependent on inotropes, and had recently had a hospitalization and/or increasing medical visits.
The device was used for any of three management strategies, Dr. Burkhoff noted: bridge to transplant, destination therapy, or bridge to decision. "We have not made a distinction between these because especially in Europe, the wait times for heart transplant are so long that these traditional boundaries are really being blurred," he explained.
The patients underwent implantation of the micropump, which is the size of a AA battery, weighs 25 g, and pumps 1.5-4.25 L/min. It is implanted subcutaneously and extrathoracically in a pacemaker pocket with an off-pump minithoracotomy procedure. The device pumps blood from the left atrium to the subclavian artery to increase circulation.
Of the 20 patients who received the most current version of the device, 82% had an implantable cardioverter-defibrillator and 65% had had cardiac resynchronization therapy.
"In terms of the postoperative care, it’s important to consider the differences between this and other VADs [ventricular assist devices]," Dr. Burkhoff maintained, noting the typically short times with the micropump to extubation (within hours), chest tube removal (1 day), and ambulation (1-2 days).
"In terms of the hemodynamic effectiveness, these data show that use of this partial support device can really interrupt and reverse the hemodynamic derangements of heart failure," he said.
Specifically, at a median follow-up of 12 weeks, patients had significant improvements from baseline in cardiac output (by about 1 L/min), pulmonary capillary wedge pressure (10 mm Hg), central venous pressure (5 mm Hg), pulmonary artery pressures (5-15 mm Hg), and pulmonary vascular resistance (1 Wood unit).
Because the device provides only partial cardiac support, the heart still beats regularly; thus, arterial systolic and diastolic pressures did not change significantly, and normal pulsatility in the arterial system was preserved.
Patients also had significant improvements in exercise tolerance as assessed with the 6-minute walk test (by 120 m) and peak VO2 (1.6 mL/kg per minute), and in end organ function, as assessed from creatinine level (0.5 mg/dL), but not in total bilirubin level (0.2 m/dL.