Hemodynamic effects of long-term cardiac resynchronization therapy: analysis by pressure-volume loops.
BACKGROUND
Acute hemodynamic effects of cardiac resynchronization therapy (CRT) were reported previously, but detailed invasive studies showing hemodynamic consequences of long-term CRT are not available.


RESULTS
We studied 22 patients scheduled for implantation of a CRT device based on conventional criteria (New York Heart Association class III or IV, left ventricular [LV] ejection fraction <35%, left bundle-branch block, and QRS duration >120 ms). During diagnostic catheterization before CRT, we acquired pressure-volume loops using conductance catheters during atrial pacing at 80, 100, 120, and 140 bpm. Studies were repeated during biventricular pacing at the same heart rates after 6 months of CRT. Our data show a significant clinical benefit of CRT (New York Heart Association class change from 3.1+/-0.5 to 2.1+/-0.8; quality-of-life score change from 44+/-12 to 31+/-16; and 6-minute hall-walk distance increased from 260+/-149 to 396+/-129 m; all P<0.001), improved LV ejection fraction (from 29+/-10% to 40+/-13%, P<0.01), decreased end-diastolic pressure (from 18+/-8 to 13+/-6 mm Hg, P<0.05), and reverse remodeling (end-diastolic volume decreased from 257+/-67 to 205+/-54 mL, P<0.01). Previously reported acute improvements in LV function remained present at 6 months: dP/dtmax increased 18%, -dP/dtmin increased 13%, and stroke work increased 34% (all P<0.01). Effects of increased heart rate were improved toward more physiological responses for LV ejection fraction, cardiac output, and dP/dtmax. Moreover, our study showed improved ventricular-arterial coupling (69% increase, P<0.01) and improved mechanical efficiency (44% increase, P<0.01).


CONCLUSIONS
Hemodynamic improvements with CRT, previously shown in acute invasive studies, are maintained chronically. In addition, ventricular-arterial coupling, mechanical efficiency, and chronotropic responses are improved after 6 months of CRT. These findings may help to explain the improved functional status and exercise tolerance in patients treated with CRT.
Steendijk
Paul
P
Department of Cardiology, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands. p.steendijk@lumc.nl
Tulner
Sven A
SA
Bax
Jeroen J
JJ
Oemrawsingh
Pranobe V
PV
Bleeker
Gabe B
GB
van Erven
Lieselot
L
Putter
Hein
H
Verwey
Harriette F
HF
van der Wall
Ernst E
EE
Schalij
Martin J
MJ
D000368:Aged; D001794:Blood Pressure; D002304:Cardiac Pacing, Artificial; D017079:Exercise Tolerance; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000628:therapy; D006339:Heart Rate; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D013318:Stroke Volume; D016896:Treatment Outcome