Effect of cardiac resynchronization therapy on left ventricular size and function in chronic heart failure.
BACKGROUND
Cardiac resynchronization therapy (CRT) has recently emerged as an effective treatment for patients with moderate to severe systolic heart failure and ventricular dyssynchrony. The purpose of the present study was to determine whether improvements in left ventricular (LV) size and function were associated with CRT.


RESULTS
Doppler echocardiograms were obtained at baseline and at 3 and 6 months after therapy in 323 patients enrolled in the Multicenter InSync Randomized Clinical Evaluation (MIRACLE) trial. Of these, 172 patients were randomized to CRT on and 151 patients to CRT off. Measurements were made of LV end-diastolic and end-systolic volumes, ejection fraction, LV mass, severity of mitral regurgitation (MR), peak transmitral velocities during early (E-wave) and late (A-wave) diastolic filling, and the myocardial performance index. At 6 months, CRT was associated with reduced end-diastolic and end-systolic volumes (both P<0.001), reduced LV mass (P<0.01), increased ejection fraction (P<0.001), reduced MR (P<0.001), and improved myocardial performance index (P<0.001) compared with control. beta-Blocker treatment status did not influence the effect of CRT. Improvements with CRT were greater in patients with a nonischemic versus ischemic cause of heart failure.


CONCLUSIONS
CRT in patients with moderate-to-severe heart failure who were treated with optimal medical therapy is associated with reverse LV remodeling, improved systolic and diastolic function, and decreased MR. LV remodeling likely contributes to the symptomatic benefits of CRT and may herald improved longer-term survival.
St John Sutton
Martin G
MG
Division of Cardiology, University of Pennsylvania Medical Center, Philadelphia, 19104, USA. suttonm@mail.med.upenn.edu
Plappert
Ted
T
Abraham
William T
WT
Smith
Andrew L
AL
DeLurgio
David B
DB
Leon
Angel R
AR
Loh
Evan
E
Kocovic
Dusan Z
DZ
Fisher
Westby G
WG
Ellestad
Myrvin
M
Messenger
John
J
Kruger
Kristin
K
Hilpisch
Kathryn E
KE
Hill
Michael R S
MR
D002304:Cardiac Pacing, Artificial / Q000379:methods; D002306:Cardiac Volume; D002908:Chronic Disease; D015331:Cohort Studies; D017147:Defibrillators, Implantable; D004311:Double-Blind Method; D015150:Echocardiography, Doppler; D004562:Electrocardiography; D005260:Female; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy; D006334:Heart Function Tests; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013318:Stroke Volume; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy