Background: Cardiac resynchronization therapy (CRT) has been demonstrated to improve ventricular-arterial coupling by reducing effective arterial elastance (Ea) on long-term follow-up. Detailed invasive studies showing possible acute peripheral effects of CRT are not available. We evaluated the hemodynamic effects of CRT in patients with systolic dysfunction, in order to investigate the impact on ventricular-arterial coupling and, in particular, on Ea immediately after the initiation of pacing.
Methods: We studied 37 heart failure patients undergoing CRT implantation based on conventional criteria. On implantation, left ventricular (LV) pressure and volume data were determined via a conductance catheter. Twelve patients with a standard indication for electrophysiologic study and preserved LV function served as a control group.
Results: In comparison with the control group, heart failure patients showed reduced systolic and diastolic function. LV end-systolic elastance (Ees: end-systolic pressure/volume) was impaired (0.79 ± 0.33 mm Hg/mL vs 1.84 ± 0.89 mm Hg/mL, P = 0.012) and Ees/Ea reduced (0.36 ± 0.17 vs 1.19 ± 1.81, P = 0.022). In heart failure patients, CRT immediately improved systolic function, increasing stroke work from 3.9 ± 1.8 L*mm Hg to 6.9 ± 3.3 L*mm Hg (P < 0.001) and Ees to 1.02 ± 0.62 mm Hg/mL (P = 0.001). Ea decreased from 2.59 ± 1.35 mm Hg/mL to 1.68 ± 0.91 mm Hg/mL (P < 0.001), leading to an increase in Ees/Ea to 0.70 ± 0.38 (P < 0.001).
Conclusion: Our data indicate that switching CRT on induces an immediate reduction in arterial load, conceivably as a consequence of restored autonomic balance.
Keywords: arterial load; cardiac resynchronization; heart failure; heart-arterial coupling; pressure-volume loop.
©2015 Wiley Periodicals, Inc.