Cardiomems PA-Pressure Sensor Guides HF Med Dosing

June 2, 2010 (Berlin, Germany)— Patients with advanced heart failure whose medications were adjusted according to readings from a tiny implanted pulmonary-artery (PA)-pressure sensor--a kind of ambulatory, permanent Swan-Ganz catheter without the catheter--saw their six-month HF-hospitalization risk drop a significant 30%, compared with standard management, in a randomized multicenter trial.

[Source: CardioMEMS]

Proponents of the PA-pressure-sensor implant (CardioMEMS, Atlanta, GA) are touting it as a potential game-changer for a difficult-to-treat class of heart-failure patients, as represented by study's participants in NYHA class 3 and with a history of being hospitalized for decompensation.

It was designed to disclose early-stage elevations in PA pressure that can be managed with appropriate medical therapy before they worsen and potentially lead to congestion. The randomized trial conducted at 63 sites in the US, called CardioMEMS Heart Sensor Allows Monitoring of Pressure to Improve Outcomes in NYHA Class III Heart Failure Patients (CHAMPION), suggests that it can do just that.

The sensor's Pulmonary-Artery Pressure Measurement System consists of the sensor itself, a catheter system for implanting it, and electronics for picking up real-time pressure readings and transmitting them to a physician. The "MEMS-based pressure sensor," 15 mm in length and 3.5 mm wide (MEMS is an engineer's acronym for microelectromechanical systems), is positioned within the pulmonary artery at right-heart catheterization. It has metal loops that help stabilize it without injuring the vessel, according to CardioMEMS. Patients receive clopidogrel and aspirin for one month after the procedure.

Speaking with heartwire , CHAMPION co–principal investigator Dr William T Abraham (Ohio State University Medical Center, Columbus) called the trial "a grand slam" for submission to the US FDA, which has a history of caution regarding the approval of implantable devices that are solely diagnostic. The study was carefully designed, he said, had a prospectively stated hypothesis, looked at important clinical outcomes, and "we hit all primary efficacy and safety end points and all secondary efficacy end points."

Abraham, along with co–principal investigator Dr Philip Adamson (Oklahoma Heart Hospital, Oklahoma City), presented CHAMPION here at the Heart Failure Congress 2010 meeting of the Heart Failure Association of the European Society of Cardiology.

For heartwire , Adamson described what he sees as another of the study's strengths: that it continued to follow most patients far longer than the six months that was prospectively defined for the primary safety analysis. The average follow-up was 15 months, during which time the gap in HF-hospitalization outcomes between patients managed and not managed with PA-pressure-guided therapy widened continuously.

"If you think about patients receiving permanent implantation of a device for the rest of their lives, had we stopped at six months, no one could [even] speculate as to what might happen in the long term," Adamson said. "I think what we're seeing when those curves continue to diverge at the end of the 15 months is a hemodynamic remodeling, in which--by managing the patient's volume aggressively and more appropriately--we begin to see reversal of the progression of the disease. With this dramatic reduction in hospitalizations, one can speculate that long term it could have an effect even on mortality."

CHAMPION's 550 patients were all implanted with the device and randomized to either standard medical management or to PA-pressure-guided medical therapy in addition to standard management. All patients checked their PA pressures daily, but physicians caring for patients in the control group were blinded to the readings. Those following the PA-pressure readings adjusted their patients' medication dosages to achieve predefined PA-pressure targets.

Management guided by the sensor led to significant reductions in the primary efficacy end point of hospitalization for heart failure at six months and in the annualized HF-hospitalization rate.

CHAMPION: Heart-Failure Hospitalization Rates at Six Months and Annualized (Based on 15-Month Mean Follow-Up)

End points	PA-pressure sensor-guided therapy (n=270) (%)	Standard management (n=280) (%)	Relative risk reduction (%)	p
HF hospitalization (primary efficacy end point)	31	44	30	<0.001
HF hospitalization (annualized rate)	45	73	38	<0.0001

"The reduction in heart-failure hospitalization also drove a statistically significant reduction in all-cause hospitalization, as well," Abraham told heartwire .

There were eight device- or system-related complications in each group, none serious, and no cases of sensor failure during the trial, which satisfied the two prospectively defined primary safety end points, he noted.

There were also secondary efficacy end points. Mean PA pressures fell substantially over six months in the sensor-guided-therapy group and rose in the control group (p=0.008 for the difference at six months). The mean number of "days alive outside the hospital" at six months was 177.1 and 175.9, respectively (p=0.022). And quality of life at six months, as assessed by the Minnesota Living with Heart Failure Questionnaire, was significantly better in the PA-pressure-guided therapy group (p=0.024).

Dr Henry Krum (Alfred Hospital, Melbourne, Australia), the featured discussant for the CHAMPION presentation, said "in terms of it becoming a truly routine procedure, I think we are perhaps some way off." But he also referred to a wave of development of implant devices that monitor hemodynamics, of which the CardioMEMS sensor is only one, as "an evolution in the way we monitor our heart-failure patients."

The CardioMEMS device, he said, "I think will be considered a landmark in this evolution. Now, we do need some more data from the CHAMPION study, but this may even be the start of a revolution in the management of heart-failure patients."

Interventional cardiologist and entrepreneur Dr Jay S Yadav is CEO and a founder of CardioMEMS and a coinventor of the device. As reported by heartwire last month, Yadav recently settled a bitter dispute with the Cleveland Clinic over allegations of conflict-of-interest nondisclosure and other issues, relating to another device he pioneered, that one for thromboembolic protection during interventional procedures.

CHAMPION was sponsored by CardioMEMS, from which Abraham and Adamson report receiving research grants and/or consulting fees.