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In people with heart failure, implanted cardiac devices with both resynchronization and defibrillation save more lives than either alone

Woods B, Hawkins N, Mealing S, et al. Individual patient data network meta-analysis of mortality effects of implantable cardiac devices. Heart. 2015;101:1800-6.

Review question

In people with heart failure with reduced ejection fraction, are some cardiac devices implanted under the skin better than others for reducing risk of death?


Heart failure occurs when your heart can’t pump blood well enough to meet the needs of your body. Ejection fraction is a measure of how well your heart is pumping blood (over 50% is normal).

Devices can be implanted below the skin and connected to the heart to help it pump better and more regularly. Such devices include cardiac resynchronization therapy (CRT) pacemakers, implantable cardioverter defibrillators (ICDs), and combined devices (CRT pacemakers with defibrillation).

How the review was done

The researchers did a systematic review, searching for studies that were published in English up to June 2011.

They included 22 randomized controlled trials with13,350 people (average age 64 years, 77% men).

The key features of the studies were:

  • people had heart failure with a left ventricular ejection fraction of 40% or less;
  • implantable cardiac devices were CRT pacemakers, ICDs, and combination devices (CRT pacemakers with defibrillation);
  • most implantable cardiac devices were compared with medical therapy alone or with each other; and
  • people were followed for an average of about 2.5 years.
  • ss=MsoListParagraphCxSpLast style='margin-left:0cm'>Trials were combined using a type of analysis that lets you compare treatments even if they were not compared directly in the individual trials.

What the researchers found

  • CRT pacemakers, ICDs, and combined devices each reduced deaths more than medical therapy alone; and
  • combined devices were better than CRT pacemakers or ICDs for reducing deaths.

More work needs to be done to determine whether some people benefit more from some devices than others.


In people with heart failure and reduced ejection fraction, implantable cardiac devices with both resynchronization and defibrillation save more lives than resynchronization pacemakers or implantable defibrillators.

Cardiac devices implanted under the skin for reducing deaths in people with heart failure and reduced ejection fraction*

Treatment comparisons

Effect on deaths at an average of 2.5 years

Combined device† vs medical therapy

Combined devices reduced deaths by about 42%‡

CRT pacemaker vs medical therapy

CRT pacemakers reduced deaths by about 28%

ICD vs medical therapy

ICDs reduced deaths by about 29%

Combined device† vs CRT pacemaker

Combined devices reduced deaths by about 19%

Combined device† vs ICD

Combined devices reduced deaths by about 18%

CRT = cardiac resynchronization therapy; ICD = implantable cardioverter defibrillator

*Trials were combined using a type of analysis that lets you compare treatments even if they were not compared directly in the individual trials.

†CRT pacemaker with defibrillation.

‡For example, if the risk of death in the medical therapy alone group was 30%, the combined device would reduce this to about 18%, a 42% relative reduction or 12% absolute reduction.



Randomized controlled trials
Studies where people are assigned to one of the treatments purely by chance.
Systematic review
A comprehensive evaluation of the available research evidence on a particular topic.

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