Improving LVEF over 0.35 after CRT has been associated with a lower ICD intervention rate, and this is also our Centre's experience. Nevertheless, I think that downgrading from a CRTD to a CRTP device needs further safety evidence. In particular, how long a CRT response can be expected to persist in the long term, expecially in progressive myocardial disease, is still unknown; furthermore, etiology should be taken into account, to suggest prudence when the disease is frequently associated with ventricular arrhythmias (Sarcoidosis, Left dominant arrhythmogenic cardiomyopathy, and lamin A/C mutation associated cardiomyopathy, just to cite a few examples). At the state of the art, I think that there is limited evidence to support downgrading, in patients  provided with an ICD lead, besides poor prognosis for copathologies, and we do not routinley choose this strategy.

This is a very good and valuable question.

We do not even have an answer to the question if you might limit your intervention to a CRT-P if your EF is less than 0.35 even if no rhythm disturbances could be documented. The answer will never be provided as the consequences of such a study are not likely to extend the present indication for a device. Hence, such a study is not likely to be financed.

For an uneventful follow up with recovery of function there will be no data either indicating that downgrading to a CRT-P will be sufficient. I would be careful but still consider such a downgrading in selected patients.    

Of important note, the average survival of a patient with CRT-D in my country is no more than 18 months. This brings the issue in still another perspective. 

I think that in responders - I mean patients who experienced an increase in EF so that their EF is > 40% at the moment of ICD replacement - this is theoretically possible. I wonder if this is ethically and legally suitable in all patients. I'd consider this downgrade in elder patients who did not experience appropriate ICD intervention in the course of the follow-up ...

In my view, in responders (EF > 40%) with who had low scar burden before implantation and no ventricular tachyarrhythmias during first CRT-D, at battery depletion CRT-P could be considered. It has to be emphasised that ICD is definitely somehow a safety measure for HF patients, but we have to take into consideration inappropriate shocks and the cost of the device. However, it goes without saying we need data through randomised trials.

This is an excellent question and one that is very difficult to answer. There is no evidence to quantify the risk of SCD in a device down grade in this sort of patient. If your patient has no history of therapies since the device was implanted and is clinically/ symptomatically stable, the risk of needing therapies in the future is not so high (but still NOT quantifiable!) particularly if the LV EF has improved.

Cardiac mIBG scanning may be considered to quantify the risk for SCD - h/m ratio of between 0.3-0.4 is associated with a high risk of SCD and h/m ratio above 0.6 has a good prognosis whilst h/m ratio below 0.25 is associated with death from pump failure (unlikely in your patient).

On the other hand, the risk of simply keeping the device "as is" is not so high in a patient who has had no complications, no therapies and no inappropriate shocks. In the absence of problems, I would be tempted to leave things alone and not downgrade the device for the moment - and this is a decision you could always revisit in the future, if required.

Well it looks like there are some answers to this interesting question in the latest post-hoc analysis of MADIT-CRT study published in Circulation October 9 2014 : Left Ventricular Ejection Fraction Normalization in Cardiac Resynchronization Therapy and Risk of Ventricular Arrhythmias and Clinical Outcomes: Results from the MADIT-CRT Trial Circulation. 

This study gave us more information of the strategy of changing the device, crtd or crt? In my opinion, downgrade\in gfrom crtd to crt is possible for the super-response patients. Also, it is needed to conduct a prospective clinical study.

This study gives us some data about occurrence of VTs in patients who achieve LVEF recovery at 12-months after CRT-D implantation. The main conclusion of the study was: »Patients who achieve LVEF normalization (>50%) have very low absolute and relative risk of VTAs and a favorable clinical course within 2.2 years of follow-up.«

According to our practice the mean time for battery change is between 4-5 years after first device implantation. Therefore, the follow-up of this study is too short to easily conclude that there are no need for the ICD in the CRT-D patients with normalise LVEF at the time of battery change. However, it is unknown if the beneficial effects of LVEF normalization will last over long-term follow-up. More prospective data are needed to confirm this on long-term follow-up after battery change.

Hi Marta, I agree with all comments above, as long as the device that is going to be replaced/downgraded requires a DF-1 connector for the shock lead. Otherwise, for DF-4 shock leads I would skip the issue because of increased risk of entering a new pacing lead for CRT-P.