Randomized comparison of simultaneous biventricular stimulation versus optimized interventricular delay in cardiac resynchronization therapy. The Resynchronization for the HemodYnamic Treatment for Heart Failure Management II implantable cardioverter defibrillator (RHYTHM II ICD) study.
BACKGROUND
The clinical value of interventricular (V-V) delay optimization in patients with chronic congestive heart failure (CHF) undergoing implantation of a device for cardiac resynchronization therapy (CRT) has not been clearly demonstrated.


METHODS
RHYTHM II was a single-blind randomized trial including 121 recipients of a device for CRT with cardioverter/defibrillator capabilities (CRT-D) randomly assigned in a 1:3 ratio to simultaneous (n = 30) versus optimized (OPT) (n = 91) biventricular pacing. V-V delay was optimized by echocardiography. The study end points were (1) freedom from CRT-D system-related complications and (2) changes between preimplant and 6 months of follow-up in (a) New York Heart Association CHF functional class, (b) distance covered during a 6-minute hall walk, and (c) quality of life (QOL).


RESULTS
In the OPT group, the V-V delay ranged from 0 to 80 milliseconds, with 28.4% of patients stimulated at an OPT V-V delay of 0 milliseconds. The overall 6-month survival free of adverse events requiring invasive interventions was 81.8%. In the whole cohort, 6 months of CRT-D was associated with a significant decrease in New York Heart Association class, increase in the distance covered during the 6-minute hall walk, and improvement in QOL (each P < .0001). The effects of CRT-D on these end points were similar in both study groups.


CONCLUSIONS
Cardioverter-defibrillator capabilities was associated with a significant alleviation of CHF symptoms, increase in functional capacity, and improvement in QOL. The optimization of the V-V delay conferred no additional benefit compared with simultaneous biventricular stimulation.
Boriani
Giuseppe
G
Institute of Cardiology, University of Bologna, Azienda Ospedaliera S.Orsola-Malpighi, Bologna, Italy. cardio1@med.unibo.it
Müller
Cord Paul
CP
Seidl
Karl Heinz
KH
Grove
Rainer
R
Vogt
Jürgen
J
Danschel
Wilfried
W
Schuchert
Andreas
A
Djiane
Pierre
P
Biffi
Mauro
M
Becker
Thorsten
T
Bailleul
Christophe
C
Trappe
Hans Joachim
HJ
D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects / Q000379:methods* / Q000401:mortality; D002908:Chronic Disease; D017147:Defibrillators, Implantable; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000503:physiopathology / Q000628:therapy*; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D016037:Single-Blind Method; D016019:Survival Analysis; D016277:Ventricular Function, Left; D016138:Walking