Archive for the ‘cardiac resynchronisation’ Category

Inserting an ICD  for  DCM  may a be great therapeutic success  for the physician  as well as the patient . But there is one big truth hidden behind the statistical screen.

Following  study  provides dramatic data from Maanhiem in Germany in about 561 patients who had ICD .The long term patient outcome after appropriate shocks were much worse  than those without    shocks .This was more pronounced in Ischemic DCM .

appropriate and inappropriate shocks ICD

Source : Streitner et al ,University Medical Centre Mannheim, Mannheim, Germany PLoS One. 2013 May 10;8(5):e6391

The fact that these patients continue to throw VT , some thing is wrong in the cellular  milieu or a fresh scar / fibrosis / ischemia is progressing .Further , the VTs and the  subsequent  shocks  set in temporary  hemodynamic instability .We have evidence , EF can be depressed for days  worsening the long-term out come.

While it is easy  to blame it on natural course of DCM , there are  solid reasons to believe  , shock induced myocardial damage is definitely contributing to this  excess mortality.

One important  clinical tip is to screen  all  these so called Idiopathic DCM  patients  who  had appropriate shocks.  They should be monitored for fresh signs of any systemic illness  , like a  connective tissue disorder , chronic granulomatous lesions  like sarcoid etc .To our surprise  some specific  myocardial disease may unmask themselves in the natural history. Identifying them may offer a dramatic cure .

Final message

Some where along our EP mind-set  we are conditioned to think  , as along as there is an ICD in situ and it appropriately  shocks, every thing is bliss ! Blame it  on semantics . The  word “appropriate”  inappropriately  soothes  our nerves.

The fact of the mater is , every appropriate shock is a  grim reminder  that the heart  in question  is restless electrically and VT continue to emanate  from diseased  myocardium  . It could  mean either the LV   is destabilising  , or the original  disease  is   progressing  or a new disease  is evolving .

Mean while, paradoxically , inappropriate shocks give us a quixotic comfort , since the  heart is not really  throwing any dangerous arrhythmia, after all it is  the device related  false alarm   that  could be easily  reprogrammed!


ICD appropriate and inappropriate shocks

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  • CRT -Cardiac resynchronisation is done  by putting multiple wires and electrically organizing the contraction  sequence and improving mechanical function.
  • ICD-Implantable cardiovertor defibrillator shocks whenever VT or VF occur and suden death is prevented.
  • CRT-D (Combo device which functions as both )

CRT is done for advanced heart failure to improve exercise capacity and hence the quality of life .It does not do any thing significant in prolonging life .ICD is again implanted  in advanced LV dysfunction with either documented VT/VF or patients who are at  propensity for VT .It has dramatic benefit in preventing  sudden cardiac death.

Both CRT and ICD has some overlapping indication in cardiac failure. Attention young cardiologists,   please realise among these two the value of ICD is many  many  fold higher than CRT.This fact is rarely discussed and disseminated.

 True benefits of CRT is realised only when it is combined with ICD.


  • Ideally all advanced cardiac failure patients should receive both ICD and CRT (CRT-D)
  • ICD as stand alone therapy has a  distinct role in patients with severe LV dysfunction (LV EF<30%) without  wide QRS in ECG
  • There is no role for  CRT  as a standalone procedure in cardiac failure  .it should  always  be combined with ICD (ie CRT-D) *

*Except  in patient with  degenerative complete heart block , both ventricles are paced  the term Bi-Vi pacing is used  instead of CRT.Since LV function is normal here , there is no de-synchrony in the first place .The synchronised  BIVI pacing is meant to prevent future heart failure

Final message

Always use a combo device in advanced symptomatic heart failure which  is refractory to medical therapy.

After all , there need to be a life in the first place  so that we can improve it . ICD ensures life while  CRT tries to improve it.


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