Sinus rhythm R-wave amplitude as a predictor of ventricular fibrillation undersensing in patients with implantable cardioverter-defibrillator.
BACKGROUND
Ventricular fibrillation (VF) is induced during implantable cardioverter-defibrillator (ICD) implantation to ensure that the ICD will sense, detect, and defibrillate VF. ICD implant guidelines state that the amplitude of the sinus rhythm R wave recorded from the ventricular electrogram should have amplitude ≥5 mV. No study has tested the relationship between sinus rhythm R-wave amplitude and VF sensing using modern, transvenous sensing electrodes.


OBJECTIVE
The goal of this study was to determine whether there is a sinus rhythm R-wave amplitude cutoff that can be used to determine which patients are not at risk of VF undersensing.


METHODS
A retrospective analysis of induced and spontaneous VF episodes from 2 clinical trials with 2022 patients was performed. Episodes with undersensing during the initial detection of VF were identified, and the distribution of sinus rhythm R-wave amplitudes for patients with and without VF undersensing was analyzed.


RESULTS
Only 3% of analyzed induced VF episodes were considered to have VF undersensing, and none had clinically significant detection delays. There was no correlation between device-measured, rectified sinus rhythm R-wave amplitude and VF undersensing at the time of implantation or during follow-up, although <4% of patients had sinus rhythm R-waves with amplitude <3 mV.


CONCLUSIONS
We analyzed true bipolar sensing of induced VF or spontaneous ventricular tachycardia/VF detected in the ICD VF zone. Sensing of VF was so reliable that clinically significant undersensing did not occur. Our findings do not support any recommended minimum sinus rhythm R wave to ensure reliable sensing of VF or the necessity of inducing VF to verify sensing for rectified sinus rhythm R-waves with amplitude ≥3 mV.
Medtronic, Inc., Minneapolis, Minnesota.
Linda L
LL
Ruetz
Medtronic, Inc., Minneapolis, Minnesota.
Jodi L
JL
Koehler
Medtronic, Inc., Minneapolis, Minnesota. Electronic address: mark.l.brown@medtronic.com.
Mark L
ML
Brown
Medtronic, Inc., Minneapolis, Minnesota.
Troy E
TE
Jackson
Medtronic, Inc., Minneapolis, Minnesota.
Paul
P
Belk
Cedars-Sinai Heart Institute; David Geffen School of Medicine at UCLA, Los Angeles, California.
Charles D
CD
Swerdlow
D000368:Aged; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019919:Prosthesis Implantation; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014693:Ventricular Fibrillation / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology*
Implant guidelines; Implantable cardioverter-defibrillator; Ventricular fibrillation