Key result
Long-term cardiac resynchronization therapy at 6 months significantly improved left ventricular ejection fraction from 29% to 40% (P<0.01) and maintained acute hemodynamic improvements.
Why the study?
Does long-term cardiac resynchronization therapy improve invasive hemodynamics, ventricular-arterial coupling, and functional status in patients with severe heart failure and left bundle-branch block?
Observational (n=22)
Does long-term cardiac resynchronization therapy improve invasive hemodynamics, ventricular-arterial coupling, and functional status in patients with severe heart failure and left bundle-branch block?
Answers are grounded in this paper and cite their sources.
Long-term cardiac resynchronization therapy provides sustained improvements in invasive hemodynamics, ventricular-arterial coupling, and mechanical efficiency, which correlate with significant clinical and functional benefits.
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. Methods and 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/dt max increased 18%, −dP/dt min 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/dt max . 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.
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Steendijk et al. (2006) conducted an observational in Heart failure (n=22). Cardiac resynchronization therapy (CRT) vs. Baseline was evaluated on Left ventricular ejection fraction (p=<0.01). Long-term cardiac resynchronization therapy at 6 months significantly improved left ventricular ejection fraction from 29% to 40% (P<0.01) and maintained acute hemodynamic improvements.
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