When shocking an out-of-sync heart, having more points of electrical contact between a device and the patient gives doctors better options to force a failing cardiac muscle to beat in rhythm again.
That's why competition continues to mount among medical device companies in the $3 billion global market for cardiac resynchronization Âtherapy (CRT) systems, balancing maximum flexibility in the operating room against the long-term battery life of an implanted device.
CRT systems are supposed to make the heart more effective in pumping blood, cutting costs and improving outcomes from a disease that kills half of its patients within five years.
Just this month, two Twin Cities-based cardiac devicemakers — Medtronic Inc. in Fridley and St. Jude Medical Inc. in Little Canada — received government approval for their latest iterations of devices that offer four electrodes to stimulate the heart, rather than the older two-electrode systems.
St. Jude is betting on a system it calls MultiPoint Pacing, which stimulates at more points than any other on the market. Medtronic officials remain skeptical of that approach, opting to refine their second generation of quadripolar stimulation devices. Boston Scientific, which has a substantial presence in the Twin Cities, has long offered its own quadripolar systems similar to how the Medtronic systems work.
Although St. Jude and Medtronic disagree on approach, each said recent clinical trials documented strong doctor preference for more electrodes from which to deliver the tiny electric shocks to the heart's lower chambers.
"I think we were all thrilled with having more options to serve our patients with this therapy," said Dr. William Katsiyiannis, cardiology president at the Minneapolis Heart Institute, who was not affiliated with either company study. "Having multiple [electrodes] to choose from allows you to get away from the limitations of the patient's anatomy."
For patients and hospitals, multiple-electrode systems cut down on the need for follow-up surgeries if glitches in the original electrode placement appear. Physicians can adjust which electrodes fire without cutting the skin, avoiding repeat trips to the hospital and Medicare's new penalties for hospital Âreadmissions.
Medtronic and St. Jude are relying on revenue growth in CRT devices to help offset long-stagnant sales of other core cardiac products, particularly traditional implantable defibrillators.
At Medtronic, sales of the Viva XT CRT defibrillator and related quadripolar leads helped drive 4 percent growth in its cardiac rhythm and heart failure business in its most recent quarter. St. Jude executives cited strong sales of their year-old Quadra and Unify CRT pacemaker systems in explaining the company's 3 percent revenue growth in the quarter. Neither company breaks out sales of CRT devices as a separate line item.
But with rates of heart failure leveling off in the U.S. in recent years, devicemakers are relying on increased market penetration, estimating that CRT systems are used by less than half of people who could benefit from them.
The per capita number of heart failure hospitalizations dropped nearly 30 percent in the Medicare population between 1998 and 2008, but the latest data cited by the Centers for Disease Control say more than 5 million Americans still have it. Heart disease was listed as a contributing cause in one of every nine deaths in the United States in 2009. And outside the U.S., heart failure is still growing.
Heart failure, contrary to its name, is not when the organ stops pumping blood. Rather, it is a weakness of the heart that manifests in out-of-sync muscle contractions, leaving the heart unable to pump enough oxygen-rich blood to the body. The goal of CRT is to force the proper timing of the left ventricle, which is the first chamber to receive oxygen-rich blood from the lungs.
CRT devices are essentially enhanced versions of traditional pacemakers and implantable defibrillators, because they deliver shocks on both sides of the heart. The systems rely on sophisticated wires called leads to deliver the shocks to the heart's surface. This month, Medtronic got U.S. approval to sell two quadripolar leads that it says offer doctors an ability to precisely use the four electrodes so they don't stimulate the phrenic nerve, which causes a constant hiccup sensation when tweaked by poorly calibrated CRT therapy.
Medtronic's new electrodes, designed for its Viva Quad CRT defibrillators, are coated with a steroid to reduce scarring and decrease the amount of energy needed to trigger the muscle.
"This is a pretty special thing. This significantly improves our ability to get really good cardiac resynchronization therapy," said Vanderbilt Heart and Vascular Institute physician Dr. George Crossley, principal investigator of the 2,000-patient Medtronic study. "It's not as Earth shattering as when we started going CRT, but it is certainly an improvement."
St. Jude is banking on a different innovation. This month it got approval in Europe to sell its Quadra Allure MP pacemaker, which allows doctors to stimulate two different points on the left ventricle with one lead, in addition to stimulating the right side with a second lead — a technique it calls MultiPoint Pacing. MPP has been available on St. Jude quadripolar devices since 2011, and data on its effectiveness is mounting.
Katsiyiannis said only about 70 percent of CRT patients show health benefits after traditional treatment, but St. Jude officials presented data at a conference in Rome earlier this month claiming a 19 percent improvement in the rate of patients who responded to the therapy when MPP was used.
"This is a step beyond quadripolar pacing," Dr. Mark Carlson, chief medical officer at St. Jude, said in an interview. "Quadripolar pacing is the way of the present. … MultiPoint Pacing is the way of the future."
The company is gathering data to test that prediction. Last year, St. Jude started enrollment in a randomized 500-patient study at 50 U.S. centers to compare the therapies side by side, under an investigational-device exemption from the Food and Drug Administration.
Dr. David Steinhaus, medical director for Medtronic's cardiac rhythm and heart-failure management business, said his company's researchers remain skeptical of MPP.
"We do not believe it works very well, if at all. And No. 2, we do know that it really drains battery energy, because you are pacing twice instead of once," Steinhaus said in an interview. "They are going to drain their battery a lot quicker, which is a big deal, because battery longevity is an issue with CRT devices."
Joe Carlson • 612-673-4779
Twitter: @_JoeCarlson
Trauma patients could be enrolled without consent in study of drugs to prevent blood loss
After many delays, $2B Iron Range project revives quest to create first new taconite mine since 1970s
What Trump's victory means for proposed mines near the BWCA in northern Minnesota
Workers, business owners crowd Minneapolis City Council presentation of contentious labor board
