Despite Guidelines, Wide Variation Found in Use of ICDs to Prevent Sudden Death in Heart Failure Patients

Despite Guidelines, Wide Variation Found in Use of ICDs to Prevent Sudden Death in Heart Failure Patients



Study results: devices are used in half of patients eligible
under current guidelines

A study of heart failure patients who meet national
guidelines for devices that stabilize and strengthen the heart’s electrical
system found that only half of eligible patients received the devices. The
study, which is the first to examine the management of heart failure patients
in outpatient cardiology practices throughout the United States, also found
wide, unexplained variations in the use of the devices, known as implantable
cardioverter-defibrillators (ICDs). The study is published in the December 2009
issue of the journal HeartRhythm.

Certain heart failure patients with weakened pumping ability
and those who develop a condition called left ventricular systolic dysfunction
after a heart attack are at risk for an irregular heart rhythm that can lead to
sudden cardiac death. The heart suddenly stops beating after an electrical
disturbance causes the heart to beat rapidly or chaotically. Extensive clinical
trial experience and national guidelines recommend the placement of ICDs in
patients with either of these conditions as a preventive measure.

“These patients have not had a major heart arrhythmia, but
they are at high risk for a rhythm abnormality and therefore meet the criteria
for device-based treatment,” says the study’s lead author, Mandeep R. Mehra,
M.B.B.S., professor of medicine, head of the Division of Cardiology at the
University of Maryland School of Medicine in Baltimore and chief of cardiology
at the University of Maryland Medical Center. “The device is implanted in order
to be available if needed. For every 14 patients implanted with an ICD, one
patient will experience a rhythm disorder that will trigger the device within
two years.”

The guidelines for device-based therapy of cardiac rhythm
abnormalities were developed by the American College of Cardiologists, the
American Heart Association and the Heart Rhythm Society. These guidelines are
Class One recommendations, which Dr. Mehra says are must-do, based on tight
evidence or clear consensus in the field that they should be done.

Study design

The study, known as IMPROVE-HF (Improve the Use of
Evidence-Based Heart Failure Therapies in the Outpatient Setting), captured
data from about six percent of the 40,000 cardiologists practicing in the U.S.
For two years, beginning in 2005, researchers reviewed the medical records of
15,381 patients in 167 community-based and academic-affiliated outpatient
cardiology practices geographically dispersed throughout the U.S. A
representative sample of records was screened from each practice to yield an
average of 90 patients per practice.

The data, which included patient demographics, medical
history, heart function, laboratory results and treatments, was reviewed by a
group of 34 chart review specialists. The investigators also evaluated the
reasons that patients did not have ICD implantation, such as patient refusal
and medical, economic or religious reasons.

 


Study findings

According to current guidelines, 7,532 patients in the study
were eligible for ICD implantation; 311 of those had documented medical
contraindications or other reasons for not receiving an ICD. Among the
remaining 7,221 eligible patients, 3,659 (50.7 percent) had devices implanted.

Patients not offered the device despite the guidelines were
most often older patients, blacks and those who did not have insurance. By contrast,
men were more likely to receive a device than women. People whose hearts did
not get enough blood and oxygen and those who had two types of heart rhythm
disorders, atrial fibrillation and wide QRS, also were more likely to receive
ICD therapy. The therapy also was more likely in patients treated with a
variety of common heart disease medications, such as beta-blockers, statins and
angiotensin-converting enzyme inhibitors.

Cardiology practices in the Northeast U.S. were more likely
to adhere to guidelines, as were those with a dedicated heart failure clinic
and those staffed with heart rhythm disorder specialists called
electrophysiologists.

The researchers note several limitations to the
interpretation of the data. A proportion of the records of patients who
appeared to be ICD-eligible lacked critical details that may have accounted for
the decision not to use the devices. For example, functional capacity, a key
measurement of heart disease severity and prognosis, was documented for only
66.5 percent of patients. Similarly, race was not consistently documented
throughout the study group, potentially obscuring the true influence of race in
the decision to use ICD therapy. ICD usage in eligible patients may be
overestimated in this study because the data came from self-selected cardiology
practices willing to participate in a quality improvement initiative.

Dr. Mehra says concerns about costs may also have figured in
the decision of some cardiologists not to use ICD therapy in certain eligible
patients. The cost of the devices and the professional and technical fees
associated with their implantation and maintenance totals about $50,000. He
says the devices have been shown to be cost-effective in the long run. But he
adds that it may be necessary to develop more refined criteria for
implantation, to make it easier to predict which patients might actually
benefit from the devices.

“This research provides useful insight into an apparent gap
in patients receiving a recommended therapy in the United States,” says E.
Albert Reece, M.D., Ph.D., M.B.A., vice president for medical affairs at the
University of Maryland and dean of the University of Maryland School of
Medicine. “Whether the gap is the result of medical or societal factors,
concerns about costs, or other issues, Dr. Mehra’s study is an important
benchmark in the effort to understand how best to treat people with
debilitating heart disease.”

Heart failure affects nearly 5 million Americans. It
develops when the heart is not able to pump enough blood to meet the body’s
needs. The heart compensates for this loss in pumping capacity by growing
larger, increasing muscle mass and pumping faster to increase the heart’s
output. Eventually, the heart and the body cannot keep up with the demands, and
the person begins to experience the fatigue and breathing problems that often
are the first signs of the disease.

The IMPROVE HF registry and this study are sponsored by
Medtronic, Inc., Minneapolis, Minnesota, a maker of ICD devices. The authors
served as consultants to Medtronic.

Mehra MR, Yancy CW, Albert NM, Curtis AB,  Stough WG, Gheorghiade M, Heywood JT,
McBride ML, O’Connor CM, Reynolds D, Walsh MN, Fonarow GC. “Evidence of
clinical practice heterogeneity in the use of implantable cardioverter defibrillators
in heart failure and post-myocardial infarction left ventricular dysfunction:
Findings from IMPROVE HF.” HeartRhythm. Volume 6, Issue 12, Pages 1727-1734
(December 2009).

SOURCE: Press release

 

 

 

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