Risk of ventricular tachyarrhythmias following improvement of left ventricular ejection fraction in patients with implantable cardiac defibrillators implanted for primary prevention of sudden cardiac death.
OBJECTIVE
In patients who undergo implantable cardiac defibrillator (ICD) implantation for primary prevention of sudden cardiac death (SCD), data is unclear whether their ICD generator needs to be replaced at end of life if their left ventricular ejection fraction (EF) improves. Despite improvement in EF, the underlying scar may represent a potential substrate for ventricular arrhythmias.


METHODS
Data on 280 patients who underwent ICD implantation for primary prevention of SCD was obtained from two centers. Patients were followed for any improvement in EF to ≥35%. All arrhythmic events during follow-up, including appropriate and inappropriate shocks/ATP, were recorded.


RESULTS
Thirty percent (n = 86/280) of patients improved their EF to >35% of which 41% (n = 37) underwent a generator change by the study ending period with the rest not yet at ERI. Mean baseline EF in patients with and without target EF improvement was 26 ± 7 and 23 ± 7% (p = 0.2). After excluding patients whose arrhythmic events data were unavailable, the final sample consisted of 62 patients in the EF improvement group and 156 patients in the group without EF improvement. In the group with EF improvement, appropriate events (shock + ATP) were noted in 19% of patients (n = 12/62) and inappropriate shocks and ATP in 6% of (n = 4/62) patients after their EF improved to >35%. Four patients received appropriate therapies when their EF was low prior to improvement. In contrast, in patients who had no improvement in EF, 27% (n = 43/156) received an appropriate therapy (p = 0.6) while 11% (n = 18/156) (p = 0.2) received inappropriate shocks and ATP. All-cause mortality was higher in patients without subsequent improvement in EF versus those with EF improvement (31 vs. 15% (p = .005).


CONCLUSIONS
There was no significant difference in the number of appropriate therapies received by each group. Patients continue to be at high risk for sudden cardiac death despite improvement in EF.
Division of Cardiology, University of Kansas Hospital, Kansas City, KS, USA. jayasreep24@gmail.com.|University of Kansas Medical Center and Hospital, 3901, Rainbow Blvd; G-600, Kansas City, KS, 66196, USA. jayasreep24@gmail.com.
Jayasree
http://orcid.org/0000-0002-9709-0203
J
Pillarisetti
Division of Cardiovascular Medicine, Robley Rex VA Medical Center and University of Louisville School of Medicine, Louisville, KY, USA.
Rakesh
R
Gopinathannair
Division of Cardiovascular Medicine, Robley Rex VA Medical Center and University of Louisville School of Medicine, Louisville, KY, USA.
Matthew J
MJ
Haney
Division of Cardiovascular Medicine, Robley Rex VA Medical Center and University of Louisville School of Medicine, Louisville, KY, USA.
Bassem
B
Abazid
Division of Cardiovascular Medicine, Robley Rex VA Medical Center and University of Louisville School of Medicine, Louisville, KY, USA.
Wasiq
W
Rawasia
Division of Cardiology, University of Kansas Hospital, Kansas City, KS, USA.|University of Kansas Medical Center and Hospital, 3901, Rainbow Blvd; G-600, Kansas City, KS, 66196, USA.
Madhu Yeruva
MY
Reddy
Division of Cardiology, University of Kansas Hospital, Kansas City, KS, USA.|University of Kansas Medical Center and Hospital, 3901, Rainbow Blvd; G-600, Kansas City, KS, 66196, USA.
Niveditha
N
Adabala
Division of Cardiology, University of Kansas Hospital, Kansas City, KS, USA.|University of Kansas Medical Center and Hospital, 3901, Rainbow Blvd; G-600, Kansas City, KS, 66196, USA.
Sudharani
S
Bommana
Division of Cardiology, University of Kansas Hospital, Kansas City, KS, USA.|University of Kansas Medical Center and Hospital, 3901, Rainbow Blvd; G-600, Kansas City, KS, 66196, USA.
Martin
M
Emert
Division of Cardiology, University of Kansas Hospital, Kansas City, KS, USA.|University of Kansas Medical Center and Hospital, 3901, Rainbow Blvd; G-600, Kansas City, KS, 66196, USA.
Dhanunjaya
D
Lakkireddy
D000368:Aged; D015984:Causality; D015897:Comorbidity; D016757:Death, Sudden, Cardiac / Q000453:epidemiology* / Q000517:prevention & control*; D017147:Defibrillators, Implantable / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D007615:Kansas / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D013318:Stroke Volume; D015996:Survival Rate; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000401:mortality*; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000401:mortality* / Q000517:prevention & control*
Generator change; Primary prevention; Sudden cardiac death