The 1+1 trial: a prospective trial of a dual- versus a single-chamber implantable defibrillator in patients with slow ventricular tachycardias.
BACKGROUND
The tachycardia detection interval (TDI) in implantable cardioverter/defibrillators (ICDs) is conventionally programmed according to the slowest documented ventricular tachycardia (VT), with a safety margin of 30 to 60 ms. With this margin, VTs above the TDI may occur. However, longer TDIs are associated with an increased risk of inappropriate therapy. We hypothesized that patients with slow VTs (<200 bpm) may benefit from a long TDI and a dual-chamber detection algorithm compared with a conventionally programmed single-chamber ICD.


RESULTS
Patients with VTs <200 bpm were implanted with a dual-chamber ICD that was randomly programmed to a dual-chamber algorithm and a TDI of > or =469 ms or to a single-chamber algorithm with a TDI 30 to 60 ms above the slowest documented VT cycle length and the enhancement criteria of cycle length variation and acceleration. The primary combined end point was the number of all inappropriate therapies, VTs above the TDI, and VTs with significant therapy delay (>2 minutes). After 6 months, a crossover analysis was performed. Total follow-up was 1 year. One hundred two patients were included in the study. The programmed TDI was 500+/-36 ms during the dual-chamber phase and 424+/-63 ms during the single-chamber phase. For the primary end point (inappropriate therapies, VTs above the TDI, or VTs with detection delay), a moderate superiority of the dual-chamber mode was found: Mann-Whitney estimator=0.6661; 95% CI, 0.5565 to 0.7758; P=0.0040.


CONCLUSIONS
Dual-chamber detection with a longer TDI improves VT detection and does not increase the rate of inappropriate therapies despite a considerable increase in tachycardia burden.
Department of Cardiology, St Georg Hospital, Hamburg, Germany. BAE151162@AOL.com
Dietmar
D
Bänsch
Frank
F
Steffgen
Gerian
G
Grönefeld
Christian
C
Wolpert
Dirk
D
Böcker
Ralph-Uwe
RU
Mletzko
Wolfgang
W
Schöls
Karlheinz
K
Seidl
Michael
M
Piel
Feifan
F
Ouyang
Stefan H
SH
Hohnloser
Karl-Heinz
KH
Kuck
D000465:Algorithms; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D019540:Area Under Curve; D003131:Combined Modality Therapy; D018592:Cross-Over Studies; D017147:Defibrillators, Implantable / Q000009:adverse effects; D004554:Electric Countershock / Q000379:methods*; D023381:Endpoint Determination; D004868:Equipment Failure; D005500:Follow-Up Studies; D006339:Heart Rate; D006801:Humans; D015993:Life Tables; D011446:Prospective Studies; D012372:ROC Curve; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology / Q000628:therapy*; D019564:Unnecessary Procedures
D000889:Anti-Arrhythmia Agents