Upgrading to resynchronization therapy after chronic right ventricular pacing improves left ventricular remodelling.
OBJECTIVE
Chronic right ventricular (RV) pacing may impose ventricular dyssynchrony leading to LV remodelling and is associated with increased morbidity and mortality. Upgrading patients with chronic RV pacing to cardiac resynchronization therapy (CRT) may be considered to restore synchronicity and prevent these deleterious effects.


RESULTS
A total of 172 patients from two tertiary centres were analysed over a mean follow-up of 21.7 and 23.5 months after primary CRT implantation (n = 102) and CRT upgrade (n = 70), respectively. In the latter group, mean duration of RV pacing before CRT upgrade was 80.3 months, and ventricular stimulation was >95%. A significant improvement in left ventricular (LV) ejection fraction (10 and 11% absolute increase in primary CRT vs. upgrades, respectively), LV end-diastolic diameter index (-0.15 cm/m(2) vs. -0.2 cm/m(2)), and LV end-systolic diameter (-6.0 vs. -7.0 mm) was observed in both groups, which did not differ between primary CRT recipients and CRT upgrades. Response to CRT upgrade was independent of the underlying rhythm, QRS duration, duration of prior RV pacing, or LV function and size at baseline. Of note, even seven of nine patients with RV pacing >12 years responded favourably to CRT.


CONCLUSIONS
The current study demonstrates that CRT reverses LV remodelling in heart failure patients with chronic RV pacing in a similar way as in primary CRT recipients, even after very long periods of RV pacing. Our data, therefore, may have important implications for the treatment of pacemaker-dependent patients with heart failure, and support the use of CRT in this setting.
Cardiovascular Center, Cardiology, University Hospital Zurich, Raemistrasse 100, Zurich CH-8091, Switzerland.
Georg
G
Fröhlich
Jan
J
Steffel
David
D
Hürlimann
Frank
F
Enseleit
Thomas F
TF
Lüscher
Frank
F
Ruschitzka
William T
WT
Abraham
Johannes
J
Holzmeister
D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D009202:Cardiomyopathies / Q000150:complications; D005260:Female; D006333:Heart Failure / Q000503:physiopathology / Q000628:therapy*; D006352:Heart Ventricles; D006801:Humans; D008134:Long-Term Care; D008297:Male; D008875:Middle Aged; D013318:Stroke Volume / Q000502:physiology; D020257:Ventricular Remodeling / Q000502:physiology*