Inductionless or limited shock testing is possible in most patients with implantable cardioverter- defibrillators/cardiac resynchronization therapy defibrillators: results of the multicenter ASSURE Study (Arrhythmia Single Shock Defibrillation Threshold Testing Versus Upper Limit of Vulnerability: Risk Reduction Evaluation With Implantable Cardioverter-Defibrillator Implantations).
BACKGROUND
Implantable cardioverter-defibrillators and cardiac resynchronization therapy defibrillators have relied on multiple ventricular fibrillation (VF) induction/defibrillation tests at implantation to ensure that the device can reliably sense, detect, and convert VF. The ASSURE Study (Arrhythmia Single Shock Defibrillation Threshold Testing Versus Upper Limit of Vulnerability: Risk Reduction Evaluation With Implantable Cardioverter-Defibrillator Implantations) is the first large, multicenter, prospective trial comparing vulnerability safety margin testing versus defibrillation safety margin testing with a single VF induction/defibrillation.


RESULTS
A total of 426 patients receiving an implantable cardioverter-defibrillator or cardiac resynchronization therapy defibrillator underwent vulnerability safety margin or defibrillation safety margin screening at 14 J in a randomized order. After this, patients underwent confirmatory testing, which required 2 VF conversions without failure at < or = 21 J. Patients who passed their first 14-J and confirmatory tests, irrespective of the results of their second 14-J test, had their devices programmed to a 21-J shock for ventricular tachycardia (VT) or VF > or = 200 bpm and were followed up for 1 year. Of 420 patients who underwent 14-J vulnerability safety margin screening, 322 (76.7%) passed. Of these, 317 (98.4%) also passed 21-J confirmatory tests. Of 416 patients who underwent 14-J defibrillation safety margin screening, 343 (82.5%) passed, and 338 (98.5%) also passed 21-J confirmatory tests. Most clinical VT/VF episodes (32 of 37, or 86%) were terminated by the first shock, with no difference in first shock success. In all observed cases in which the first shock was unsuccessful, subsequent shocks terminated VT/VF without complication.


CONCLUSIONS
Although spontaneous episodes of fast VT/VF were limited, there was no difference in the odds of first shock efficacy between groups. Screening with vulnerability safety margin or defibrillation safety margin may allow for inductionless or limited shock testing in most patients.
Day
John D
JD
Utah Heart Clinic Arrhythmia Service, LDS Hospital, 324 10th Ave, #206, Salt Lake City, UT 84103, USA. john.day@cv-research.org
Doshi
Rahul N
RN
Belott
Peter
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Birgersdotter-Green
Ulrika
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Behboodikhah
Mahnaz
M
Ott
Peter
P
Glatter
Kathryn A
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Tobias
Serge
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Frumin
Howard
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Lee
Byron K
BK
Merillat
John
J
Wiener
Isaac
I
Wang
Samuel
S
Grogin
Harlan
H
Chun
Sung
S
Patrawalla
Rob
R
Crandall
Brian
B
Osborn
Jeffrey S
JS
Weiss
J Peter
JP
Lappe
Donald L
DL
Neuman
Stacey
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D000368:Aged; D000369:Aged, 80 and over; D001145:Arrhythmias, Cardiac / Q000150:complications / Q000188:drug therapy / Q000628:therapy*; D002317:Cardiovascular Agents / Q000627:therapeutic use; D003131:Combined Modality Therapy; D018592:Cross-Over Studies; D016757:Death, Sudden, Cardiac / Q000517:prevention & control; D017147:Defibrillators, Implantable / Q000592:standards; D004558:Electric Stimulation; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012107:Research Design; D040242:Risk Reduction Behavior; D016037:Single-Blind Method; D019564:Unnecessary Procedures; D014693:Ventricular Fibrillation / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control* / Q000628:therapy
D002317:Cardiovascular Agents