Author Insights: Study Finds Single-Chamber Implantable Defibrillators Safer and as Effective as Newer Dual-Chamber Devices

Pamela N. Peterson, MD, MSPH, of the Denver Health Medical Center in Colorado, and colleagues found that use of newer dual-chamber implantable defibrillators for primary prevention of life-threatening heart arrhythmias did not result in clinical outcomes that were any better than those associated with use of single-chamber devices and resulted in higher complication rates. (Image: Denver Health Medical Center)

Pamela N. Peterson, MD, MSPH, of the Denver Health Medical Center in Colorado, and colleagues found that use of newer dual-chamber implantable defibrillators for primary prevention of life-threatening heart arrhythmias did not result in clinical outcomes that were any better than those associated with use of single-chamber devices and resulted in higher complication rates. (Image: Denver Health Medical Center)

Sometimes, more is not better, as researchers report in a new study of implantable defibrillators, devices that use electrical shocks to prevent sudden cardiac arrest in people with potentially life-threatening heart arrhythmias. In research published today in JAMA, investigators found that implantation of newer “dual-chamber” implantable cardioverter-defibrillators (ICDs) is associated with a higher risk of device-related complications when compared with single-chamber ICDs. At the same time, rates of hospitalization or death among patients during the first year after implantation were the same regardless of whether patients received a single- or dual-chamber device.

In theory, compared with single-chamber devices, dual-chamber ICDs produce electrograms that are easier for physicians to interpret, and these devices are better able to identify dangerous arrhythmias, reducing unnecessary electrical shocks. But dual-chamber ICDs are more difficult to implant and may be associated with more infections and displacement of wires, or leads, requiring reoperations.

For the JAMA article, researchers retrospectively studied 32 034 patients who received a single-chamber or dual-chamber device for primary prevention (to prevent sudden cardiac arrest in people who are at high risk for this problem) from 2006 to 2009. Complication rates were 3.51% for single-chamber devices compared with 4.72% for dual-chamber devices. Rates of 1-year mortality, as well as 1-year all-cause hospitalization or hospitalization for heart failure, were similar. The increased complication rate without an apparent increase in benefit led the researchers to ask why almost two-thirds of all ICDs implanted in this population for primary prevention were dual-chamber devices.

Lead author Pamela N. Peterson, MD, MSPH, an associate professor of medicine at the Denver Health Medical Center in Colorado, discusses her team’s findings:

news@JAMA: What prompted you to study single-chamber versus dual-chamber ICD use for primary prevention?

Dr Peterson: We had several reasons. First, the major trials that looked at primary prevention with ICDs predominately tested single-chamber devices, and when dual chambers came out, there was little study of their effects for primary prevention. Second, with the introduction of dual-chamber ICDs, we saw practice pattern changes, with a significant number of patients receiving them. Third, we also saw great geographical variation in the use of single- or dual-chamber ICDs that was not associated with patient characteristics.

news@JAMA: You compared the devices in terms of primary prevention of life-threatening arrhythmias. What are the characteristics of a patient that would suggest implanting an ICD for primary prevention?

Dr Peterson: They can be patients who have a reduced ejection fraction: their heart function is weak. Also, those at high risk for these irregular heart rhythms, who are at risk for sudden cardiac arrest.

news@JAMA: Why have clinicians turned to implanting dual-chamber ICDs for the primary prevention of dangerous arrhythmias?

Dr Peterson: As technology advances, it is hard to believe the advanced technology is not better than the prior technology. One theoretical benefit of the dual chamber is that it is better able to detect and differentiate a lethal from nonlethal arrhythmia, but the data have yet to show that. Also, the culture of practice is a significant player in this geographic variation we observed. It becomes a “this is the way we do it here” culture.

news@JAMA: What issues do patients discuss with clinicians when they are being considered for an ICD?

Dr Peterson: The decision whether to receive a device at all is the most important decision, and there aren’t great data to support one device over the other. Once it’s decided that a patient needs a device, the choice of single chamber or dual chamber often doesn’t involve the patient. It’s often a physician-level decision.

Author Insights: Many Devices Approved Without Comparative Effectiveness Data


Rita Redberg, MD, a professor of medicine at the University of California, San Francisco, and colleagues found that many high-risk cardiovascular devices were approved without data on their comparative effectiveness. Image: University of California, San Francisco

About half of high-risk cardiac devices approved by the US Food and Drug Administration (FDA) were approved without comparative data on whether they provide better outcomes than other treatment options, found an analysis published online in JAMA.

Advances in medical technology have led to the emergence of devices such as stents, defibrillators, and mechanical heart valves to support or sustain the life of individuals with cardiovascular conditions. These devices are considered high risk because their implantation may require invasive procedures or because once implanted, they are necessary to sustain life. Because of this, many physicians and patients may be surprised to learn that such FDA-approved devices do not have to meet the same high standards of evidence required for drugs used to treat cardiovascular disease. Companies that seek FDA approval for a drug, for example, must conduct 2 randomized controlled trials to compare the effects of their product with a placebo or with another treatment (a so-called active comparator or active control) for the condition. But device makers are not required to submit study data involving an active control. Continue reading

JAMA Forum: Bill Would Gut Patient-Centered Outcomes Research

Aaron Carroll, MD, MS

Aaron Carroll, MD, MS

Last week, the House Appropriations subcommittee on labor, health and human services, and education approved a spending bill, which moves along this week to the full committee for consideration and possible amendments. Then, it’s on to a vote in the House of Representatives.

The bill is generating a fair amount of attention because it takes some drastic steps with respect to government funding of research. Specifically, per Academy Health: Continue reading

Author Insights: Refocus Questionable US-Funded Complementary and Alternative Therapies Research

Paul A. Offit, MD, of Children’s Hospital in Philadelphia, says that much federally funded research of alternative and complementary medicine is misguided. (Image: April Saul at the Philadelphia Inquirer)

The mission of the National Institutes of Health’s (NIH) National Center for Complementary and Alternative Medicine (NCCAM) is “to define, through rigorous scientific investigation, the usefulness and safety of complementary and alternative medicine interventions and their roles in improving health and health care.” In the 2 decades since the center was created (initially with the name of the Office of Alternative Medicine), NCCAM has spent $1.6 billion funding studies and has a current annual budget of $130 million.

In a Viewpoint appearing today in JAMA, Paul A. Offit, MD, chief of the division of infectious diseases and director of the Vaccine Education Center at the Children’s Hospital of Philadelphia, argues that NCCAM-funded scientific investigation has failed to uncover many successful uses for complementary and alternative medicine, and these negative findings have had little effect on changing certain practices and patient perceptions. He notes that NCCAM has spent $374 000 to find that inhaling lemon and lavender scents does not promote wound healing; $750 000 to find that prayer does not cure AIDS or speed recovery from breast reconstruction surgery; and $700 000 to find that magnets do not offer relief from arthritis, carpal tunnel syndrome, or migraine headaches. At best, he said, many of these studies reaffirm the placebo effect among certain patients undergoing these therapies. Continue reading

Author Insights: Newer Radiation Therapy for Prostate Cancer More Expensive But Not Necessarily More Effective

Ronald C. Chen, MD, MPH, of the University of North Carolina at Chapel Hill, and colleagues found that expensive proton therapy for prostate cancer does not reduce the risk of recurrence of the disease and may increase gastrointestinal risks when compared with current radiation therapy. (Image: Brian Strickland)

An emerging type of radiation therapy for treating localized prostate cancer called proton therapy appears to be no better in reducing the risk of disease recurrence than the current standard of radiotherapy care, intensity-modulated radiation therapy (IMRT), but it is far more costly and also appears to increase the risk of gastrointestinal complications. These findings appear today in JAMA as part of the journal’s comparative effectiveness research theme issue.

Prostate cancer is the most common malignancy in men, resulting in about 200 000 diagnoses and 30 000 deaths each year in the United States. The ability to diagnose prostate cancer early and the slow-growth nature of the disease give men and their physicians various treatment options. About 30% to 40% of men with prostate cancer choose to undergo radiation; others may opt for watchful waiting or surgery, depending on such factors as age, the stage and grade of their cancer, and their personal preferences.

The JAMA researchers, using data from the SEER-Medicare database (a linkage of 2 large population-based sources of data that provide detailed information about Medicare beneficiaries with cancer), also found IMRT did better than a less recently developed form of radiotherapy, conformal radiation, but this efficacy was not determined until after IMRT use grew from 0.15% of patients undergoing radiation in 2000 to 95.9% in 2008. Continue reading

For Many Women, Pelvic Floor Muscle Exercises Trump Drugs in Reducing Bladder Leaks

Many women develop urinary incontinence, but exercises to strengthen the pelvic floor muscles may help with few adverse effects. Image: iStockphoto.com/Henrik Jonsson

When women’s perspectives on treatment success are considered, pelvic floor muscle exercises are effective at reducing urinary incontinence in women with fewer adverse effects than drug-based treatment, according to a review by the Agency for Healthcare Research and Quality (AHRQ).

About a quarter of young women and more than half of middle-aged and postmenopausal women experience involuntary urine loss after a strong urge to urinate or when they sneeze or cough. This condition can have deleterious effects on women’s physical, psychological, and social well-being, according to a statement from AHRQ Director Carolyn M. Clancy, MD. But many reviews of the evidence on the most effective treatments for the condition have focused on objective measures, such as volume of urine loss or frequency of urine loss, with less emphasis on women’s satisfaction with treatment outcomes and the effect of treatment on their quality of life. The AHRQ review took a more patient-centered approach. Continue reading

Author Insights: ICU Patients May Benefit From Alternative Sedative

Jukka Takala, MD, PhD, director of the department of intensive care medicine at Bern University Hospital in Switzerland, and his colleagues found evidence that using dexmedetomidine as a sedative for patients in the intensive care unit may offer advantages. Image: Inselspital, Bern University Hospital

Sedation is often required for patients in the intensive care unit (ICU) who are breathing with the assistance of a mechanical ventilator. But patients who are sedated for long periods can experience serious adverse effects, including delirium, posttraumatic stress disorder, or coma. To minimize such effects, many ICU clinicians have begun providing patients with daily breaks from sedation and exploring other strategies to reduce risks to patients, including identifying the safest sedatives.

A pair of clinical trials involving nearly 1000 ICU patients, published today in JAMA by a team of European researchers, suggests that the sedative dexmedetomidine may offer some advantages over 2 sedatives used more frequently in ICUs in the United States, propofol and midazolam. Both multicenter trials found that dexmedetomidine was not inferior to the 2 more commonly used sedatives. The trials were sponsored by Orion Pharma, Espoo, Finland.

One trial, MIDEX, found that patients treated with dexmedetomidine spent less time on mechanical ventilation and had their breathing tubes removed faster than patients taking midazolam. The other trial, PRODEX, found that dexmedetomidine-treated patients had their breathing tubes removed more quickly than did patients treated with propofol, but the difference in the total time spent on ventilation was not significant. Continue reading