AUTHOR=Frey Simon Martin , Brenner Roman , Theuns Dominic A. , Al-Shoaibi Naeem , Crawley Richard J. , Ammann Peter , Sticherling Christian , Kühne Michael , Osswald Stefan , Schaer Beat 

TITLE=Follow-up of CRT-D patients downgraded to CRT-P at the time of generator exchange

JOURNAL=Frontiers in Cardiovascular Medicine

VOLUME=Volume 10 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/cardiovascular-medicine/articles/10.3389/fcvm.2023.1217523

DOI=10.3389/fcvm.2023.1217523

ISSN=2297-055X

ABSTRACT=Background
Some patients with cardiac resynchronisation therapy (CRT) experience super-response (LVEF improvements to >50%). At generator exchange (GE), downgrading (DG) from CRT-defibrillator (CRT-D) to CRT-pacemaker (CRT-P) could be an option for these patients on primary prevention ICD indication and no required ICD therapies. Long-term data on arrhythmic events in super-responders is scarce. 
Methods
CRT-D patients with LVEF improvement to >50% at GE were identified in four large centres for retrospective analysis. Mortality, significant ventricular tachyarrhythmia and appropriate ICD-therapy were determined, and patient analysis was split into two groups (downgraded to CRT-P or not). 
Results
Sixty-six patients (53% male, 26% coronary artery disease) on primary prevention were followed for a median of 129 months [IQR 101-155] after implantation. 27 (41%) patients were downgraded to CRT-P at GE after a median of 68 [IQR 58-98] months (LVEF 54±4%). The other 39 (59%) continued with CRT-D therapy (LVEF 52±6%).
No cardiac death or significant arrhythmia occurred in the CRT-P group (median follow-up (FU) 38 months [IQR 29-53]). Three appropriate ICD-therapies occurred in the CRT-D group (median FU 70 months [IQR 39-97]). Annualized event-rates after DG/GE were 1.5% and 1.0%/year in the CRT-D group and the whole cohort, respectively. 
Conclusions
No significant tachyarrhythmia were detected in the patients downgraded to CRT-P during follow-up. However, three events were observed in the CRT-D group. Whilst downgrading CRT-D patients is an option, a small residual risk for arrhythmic events remains and decisions regarding downgrade should be made on a case-by-case basis.