implantable cardioverter-defibrillators

A new meta-analysis published in Circulation assessed randomized clinical trials for the use of implantable cardioverter-defibrillators (ICDs) in non-ischemic cardiomyopathies. The results favoured the use of ICDs to treat cardiomyopathies.


Cardiomyopathies are diseases that affect the heart muscle. This can occur in many ways such as causing the heart muscle to thicken, or causing the ventricles to weaken. Ischemic cardiomyopathy (ICM) is a subgroup of cardiomyopathies in which the coronary arteries, which supply blood to the heart, become narrow and restricted. This limits the amount of oxygen that can reach the heart resulting in cellular death of the heart’s muscular layer.

Implantable cardioverter-defibrillators (ICDs) have been a huge advancement for patients with ICM. Similar to pacemakers, ICDs are small devices that are placed inside the chest cavity which use electrical pulses to control arrhythmias. When arrhythmias, or irregular heartbeats, occur, the heart has difficulty pumping blood to the body, which can result in death within minutes. In a hospital setting, arrhythmias would be treated with defibrillation. However, ICDs connect electrodes to the heart chambers, and, upon detecting an arrhythmia, will send electrical pulses to the heart to restore a normal rhythm.

Despite the widespread use of ICDs in ICM, there is limited data for the use of ICDs in patients with non-ischemic cardiomyopathy (NICM). A new study published in the Circulation conducted a meta-analysis of randomized clinical trials assessing ICDs in NICM.

The authors identified 6 clinical trials with a total of 2970 patients with NICM. Upon pooling the data, they found that ICD therapy reduced all-cause mortality by 23% in patients with NICM. This was a substantial finding supporting the use of ICDs in other cardiomyopathies.

Overall, the results of this study favour the use of ICDs to treat cardiomyopathies. A large limitation of this meta-analysis is that only 6 clinical trials for the use of ICDs exist with a limited number of individuals. Further clinical trials are warranted for assessing ICDs in cardiomyopathies and other cardiologic disorders.

Written By: Neeti Vashi, BSc

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