Pacemakers that pace the heart's upper and lower chambers are more expensive than the standard devices but they are worth the extra cost, according to a study published in Circulation, the journal of the American Heart Association (AHA; Dallas). The dualchamber pacemakers save significant money because they reduce the risk of hospitalization and disability in patients with heart disease. The more complex pacemakers "significantly reduced the rates of atrial fibrillation and heart failure hospitalizations, which over the long term results in a highly favorable cost-effectiveness ratio," said David Cohen, MD, associate professor of medicine at Harvard Medical School (Boston). Single-chamber or right-ventricular pacemakers "pace" a ventricle, one of the heart's two large, lower pumping chambers. Dual-chamber devices also pace one of the atria (the smaller, upper chambers), which is considered a more natural synchronization.

Cohen, senior author of the study, said that during the first four years after implant the dual-chamber devices had a cost-effectiveness ratio of $53,000 per quality-adjusted year of life gained. "In the U.S. healthcare system, cost-effectiveness ratios between $50,000 and $100,000 per quality-adjusted year of life gained are generally considered to be in the gray zone of attractiveness as healthcare expenditures," Cohen said. "But when we used a computer simulation model to estimate lifetime costs and benefits, the dual-chamber devices were associated with an average cost-effectiveness ratio of $6,000 to $7,000 cost per quality-adjusted life year gained compared with single-chamber pacing. That is very favorable."

The four-year, 2,010-patient Mode Selection in Sinus Node Dysfunction (MOST) study randomized 1,014 patients to dual-chamber devices and 996 to right-ventricular (single-chamber) pacing devices. The median age of patients was 74; 48% were women. The National Heart, Lung and Blood Institute of the National Institutes of Health (both Bethesda, Maryland) sponsored the trial. All of the patients had sick sinus syndrome, meaning they had very slow heartbeats along with symptoms such as lightheadedness, dizziness, fainting or general fatigue. The condition is diagnosed by electrocardiogram, Cohen said.

Since the dual-chamber devices didn't reduce mor-tality, the favorable cost-effectiveness observed in the study was "derived mainly from improved quality of life fewer hospitalizations, less disability," Cohen said. Patients who received the dual-chamber devices were less likely to develop AF, or to be hospitalized for heart failure, than those who received single-chamber pacemakers. Patients receiving the dual-chamber dev-ices also had a slightly lower risk of death or stroke, had better results on a heart failure score, and relatively small, but significantly better results on several measures of health-related quality of life.

Although dual-chamber pacemakers cost about $3,000 more than single-chamber devices (including the cost of implantation) during the first four years, the cumulative cost for a patient with a dual-chamber device was $27,441. The cumulative cost for someone with a single-chamber device was $26,760. When cost data from the first four years were fed into a computer model that estimated lifetime costs, the dual-chamber pacemaker had a discounted lifetime cost of $59,104, while the discounted lifetime cost for the ventricular pacemaker was estimated at $58,160.

The study's results may serve to bolster enhanced reimbursement and an expanded patient pool for the more costly devices. The primary beneficiaries of this windfall would be large players in the pacemaker market, including Medtronic (Minneapolis), Guidant (Indianapolis) and St. Jude Medical (St. Paul, Minnesota).

Included in the analysis were the costs of pacemaker implantation (hardware, hospital fees, professional fees), outpatient follow-up (emergency department visits, unscheduled outpatient visits, and half of scheduled visits during the trial), medication, and rehospitalization for cardiovascular events (AF, heart failure, stroke). Time costs and out-of pocket costs were not included, as the authors expected these to be very small compared with medical care costs.

The authors concluded that, compared with ventricular pacemakers, the dual-chamber devices have a projected gain of 0.17 quality-adjusted life years compared with single-chamber devices. "Although this increase in quality-adjusted years of life may seem modest, it compares favorably with other medical advances, including r-tPA vs. streptokinase for suspected acute myocardial infarction, about 0.06 to 0.29 years of life, beta-blockers for low-risk survivors of heart attack, about 0.10 years of life, and stenting vs. balloon angioplasty for single-vessel coronary revascularization, about 0.03 quality-adjusted years of life," they said.

CVD continues as No. 1 killer in U.S.

Cardiovascular disease (CVD) claimed the lives of 927,448 Americans in 2002, according to the Heart Disease and Stroke Statistics-2005 Update, released by the American Heart Association in late December. This figure puts CVD as still the nation's No. 1 killer. The update also includes a new section on the metabolic syndrome (MetS) in adolescents that indicates that rates of controllable risk factors for cardiovascular diseases are increasing among America's young people. The 2005 Update compiles statistics for 2002 or the most recent year that data are available.

Cardiovascular diseases include high blood pressure, coronary heart disease (heart attack and angina), congestive heart failure, stroke and congenital heart defects, among others. The update includes recently published data from the 1999-2002 National Health and Nutrition Examination Survey (NHANES), showing that about 65 million Americans had high blood pressure in 2002 a 30% increase over the previous survey from 1988-94. There were 494,382 coronary heart disease deaths in 2002, including 179,514 deaths from heart attack. This year, an estimated 700,000 Americans will have a coronary attack, and about 500,000 will have a recurrent attack, according to the AHA.

As a footnote to the figures segmented out, coronary heart disease, considered alone, has fallen slightly behind deaths from cancers among those under age 85, as reported by the American Cancer Society (Atlanta) last month in its annual statistical summary for 2002. Its figure for "heart disease" deaths for this under85 group in that year is 450,637 as compared to cancer deaths totaling 476,009.

Stroke accounted for 162,672 deaths in 2002 and 942,000 hospital discharges, according to the AHA. "While heart attacks and stroke remain the leading causes of death in men and women, we see in the 2005 Update that many risk factors for these conditions are common, preventable and occur well before the onset of disease," said Christopher O'Donnell, MD, associate director of the Framingham Heart Study of the National Heart, Lung and Blood Institute and chair of the AHA's statistics committee. "These risk factors, including abnormal blood lipids and high blood pressure, often present early in life even before middle age, when preventative measures might make a large difference."

The new statistics also show that nearly 4 million children ages 6-11 and 5.3 million adolescents ages 12-19 were overweight or obese in 2002. And more children are overweight or obese at very young ages. More than 10% of preschool children between the ages of 2 and 5 were overweight in 2002 up from 7% in 1994.

Following MI, gene repair swings into action

In the most comprehensive study of its kind, new data is shedding light on the important gene expression changes that occur in the heart following myocardial infarction (MI). Data from this study gathered by researchers at Allegheny General Hospital (Pittsburgh) using GE Healthcare's (Waukesha, Wisconsin) CodeLink were published in the January issue of the Journal of Molecular and Cellular Cardiology.

A major finding of the study was that genes affected by a MI are not deactivated; rather they attempt to repair and rejuvenate in the area of the heart that was affected. MI, or heart attack, occurs when the blood supply to the myocardium, a part of the heart muscle, is severely reduced or stopped. And if blood supply is cut off for more than a few minutes, muscle cells suffer permanent injury and die.

"The results of this study raise the possibility of developing revolutionary new treatments to minimize the impact of MI. Understanding in more detail the complex pattern of the changes activated by myocardial injury will allow the medical community to develop therapies that may preserve heart muscle before it deteriorates," said Robert Guthrie, MD, director, division of neonatology, Allegheny General Hospital, and professor of pediatrics, Drexel University School of Medicine (Philadelphia)

This pre-clinical study was undertaken to outline the multiple molecular processes that occur in the heart following an MI. Successful MI compensation involved early remote zone gene activation, including an acute phase response, initiation of a cytoprotective program, recruitment of extensive developmental transcription factors and induction of signaling pathways associated with cell proliferation.

No Comments