Fusion-optimized intervals (FOI): a new method to achieve the narrowest QRS for optimization of the AV and VV intervals in patients undergoing cardiac resynchronization therapy.
BACKGROUND
Optimization of atrioventricular (AV) and interventricular (VV) intervals may improve cardiac resynchronization therapy (CRT) response but is a complex task. Fusion with intrinsic conduction may increase the benefit of CRT. The aim was to describe fusion-optimized intervals (FOI), a new method of optimizing CRT based on QRS duration.


RESULTS
Seventy-six consecutive patients with preserved AV conduction who received CRT were prospectively included. The AV interval was optimized by searching the narrowest QRS obtained within the fusion band during left ventricular (LV) pacing. The VV interval was then adjusted, comparing QRS duration in simultaneous biventricular, LV preexcitation (-30 milliseconds), right ventricular (RV) preexcitation (-30 milliseconds) and LV-only pacing. A substudy in 31 patients evaluated the invasive LV +dP/dtmax . The best fusion-optimized AV interval was 136 ± 30 milliseconds during atrial sensing and 192 ± 35 milliseconds during atrial pacing. The best QRS was obtained with simultaneous biventricular pacing in 28 patients (37%), LV preexcitation in 22 (29%), LV-only in 20 (26%), and RV preexcitation in 6 (8%). Baseline QRS was shortened more by FOI (59 ± 19 milliseconds) than by nominal settings (40 ± 21 milliseconds; P < 0.001). Sixty-five patients (86%) showed >10% shortening of the baseline QRS with FOI; none prolonged the QRS duration by FOI compared to nominal settings. All echocardiographic asynchrony parameters were corrected by FOI. Baseline +dP/dtmax improvement was greater in FOI (127 ± 95 mmHg/seconds) than in nominal settings (102 ± 71 mmHg/seconds; P = 0.05).


CONCLUSIONS
The FOI method is feasible, further reduces QRS duration, and improves acute hemodynamic response compared to nominal programming of CRT.
Cardiology Department-Thorax Institute-Hospital Clínic, University of Barcelona Institut d' Investigació Biomèdica August Pi i Sunyer (IDIBAPS), Barcelona, Spain.
Elena
E
Arbelo
José María
JM
Tolosana
Emilce
E
Trucco
Diego
D
Penela
Roger
R
Borràs
Adelina
A
Doltra
David
D
Andreu
Marta
M
Aceña
Antonio
A
Berruezo
Marta
M
Sitges
Fadi
F
Mansour
Angeles
A
Castel
Mariona
M
Matas
Josep
J
Brugada
Lluís
L
Mont
D000368:Aged; D001283:Atrioventricular Node / Q000502:physiology*; D058406:Cardiac Resynchronization Therapy / Q000379:methods* / Q000639:trends; D058409:Cardiac Resynchronization Therapy Devices / Q000639:trends; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies
cardiac resynchronization therapy; electrocardiogram; fusion; optimization