Role of defibrillation threshold testing during implantable cardioverter-defibrillator placement: data from the Israeli ICD Registry.
BACKGROUND
Defibrillation threshold (DFT) testing during placement of an implantable cardioverter-defibrillator (ICD) has been considered mandatory. Accumulating data suggest a more limited role for DFT.


OBJECTIVE
The purpose of this study was to compare the outcome of ICD recipients who underwent DFT testing compared with those who did not.


METHODS
In this prospective cohort analysis of patients who received an ICD between July 2010 and March 2013, we compared patients who underwent DFT testing and those who did not. Primary end-points were death and malignant ventricular arrhythmias. Secondary end-points included the composite end-points and inappropriate ICD discharges.


RESULTS
Of the 3596 patients in the registry, 614 patients (17%) underwent DFT testing during ICD placement vs 2982 (83%) who did not. Variables associated with ICD testing were implantation for secondary prevention (relative risk [RR] 1.87), prior ventricular arrhythmias (RR 1.81), use of antiarrhythmic medication (RR 1.59), and sinus rhythm (RR 2.05). Factors predisposing against testing were cardiac resynchronization therapy defibrillator implantation (RR 0.56) and concomitant diuretic use (RR 0.71). ICD testing was not associated with 1-year mortality (5.3% vs 5.1%, P = .74), delivery of appropriate shocks (8.6% vs 5.6%, P = .16), combined outcomes of ventricular arrhythmias and death (12.9% vs 11.3%, P = .45), or inappropriate ICD discharges (3.9% vs 2.1%, P = .2) compared to no DFT testing.


CONCLUSIONS
No significant differences in the incidence of mortality, malignant ventricular arrhythmias, or inappropriate ICD discharges were observed between patients who underwent DFT testing compared to those who did not. Our results may support avoiding DFT testing during ICD placement, but this requires confirmation by additional prospective studies.
Department of Cardiology, Meir Medical Center, Kfar Saba, Israel. Electronic address: yoav.arnson@gmail.com.
Yoav
Y
Arnson
Rambam Medical Center, Haifa, Israel.
Mahmoud
M
Suleiman
Department of Cardiology, Tel Hashomer Medical Center, Tel Aviv, Israel.
Michael
M
Glikson
Naharia Medical Center, Naharia, Israel.
Ron
R
Sela
Department of Cardiology, Wolfson Medical Center, Holon, Israel.
Michael
M
Geist
Department of Cardiology, Soroka Medical Center, Beer Sheva, Israel.
Guy
G
Amit
Heart Institute, Carmel Medical Center, Haifa, Israel.
Jorge E
JE
Schliamser
Department of Cardiology, Tel Hashomer Medical Center, Tel Aviv, Israel.
Ilan
I
Goldenberg
Department of Cardiology, Tel Hashomer Medical Center, Tel Aviv, Israel.
Shlomit
S
Ben-Zvi
Department of Cardiology, Rabin Medical Center, Petah Tikva, Israel.
Katia
K
Orvin
Arrhythmia Therapy Center, Heart Institute, Hadassah Hebrew University Medical Center, Jerusalem, Israel.
Shimon
S
Rosenheck
Department of Cardiology, Ha׳Emek Medical Center, Afula, Israel.
Nahum
N
Adam Freedberg
Department of Cardiology, Rabin Medical Center, Petah Tikva, Israel.
Boris
B
Strasberg
Department of Cardiology, Meir Medical Center, Kfar Saba, Israel.
Moti
M
Haim
D016757:Death, Sudden, Cardiac / Q000453:epidemiology / Q000517:prevention & control*; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007557:Israel / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D012042:Registries; D012307:Risk Factors; D015996:Survival Rate / Q000639:trends; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000503:physiopathology / Q000628:therapy*
Complications; Defibrillation threshold; Defibrillation threshold testing; Implantable cardioverter-defibrillator; Mortality; Outcomes