Echocardiographic quantification of left ventricular asynchrony predicts an acute hemodynamic benefit of cardiac resynchronization therapy

Abstract

Objectives

We sought to determine whether radial left ventricular (LV) asynchrony in patients with heart failure predicts systolic function improvement with cardiac resynchronization therapy (CRT).

Background

We quantified LV wall motion by echocardiography to correlate the effects of CRT on LV systolic function with wall motion synchrony.

Methods

Thirty-four patients underwent echocardiographic phase analysis of LV septal and lateral wall motion and hemodynamic testing before CRT. Phase relationships were measured by the difference between the lateral (Φ_L) and septal (Φ_S) wall motion phase angles: ΦLS = ΦL − ΦS. The absolute value of Φ_LS was used as an order-independent measure of synchrony: |ΦLS| = |ΦL − ΦS|.

Results

Three phase relationships were identified (mean ± SD): type 1 (n = 4; peak positive LV pressure [dP/dt_max] 692 ± 310 mm Hg/s; Φ_LS = 5 ± 6°, synchronous wall motion); type 2 (n = 17; dP/dt_max 532 ± 148 mm Hg/s; Φ_LS = 77 ± 33°, delayed lateral wall motion); and type 3 (n = 13; dP/dt_max 558 ± 154 mm Hg/s; Φ_LS = −115 ± 33°, delayed septal wall motion, triphasic). A large |Φ_LS| predicted a larger increase in dP/dt_max with CRT (r = 0.74, p < 0.001). Sixteen patients were studied during right ventricular (RV), LV and biventricular (BV) pacing. Cardiac resynchronization therapy acutely reduced |Φ_LS| from 104 ± 41° (OFF) to 86 ± 45° (RV; p = 0.14 vs. OFF), 71 ± 50° (LV; p = 0.001 vs. OFF) and 66 ± 42° (BV; p = 0.001 vs. OFF). A reduction in |Φ_LS| predicted an improvement in dP/dt_max in type 2 patients for LV (r = 0.87, p = 0.005) and BV CRT (r = 0.73, p = 0.04).

Conclusions

Echocardiographic quantification of LV asynchrony identifies patients likely to have improved systolic function with CRT. Improved synchrony is directly related to improved hemodynamic systolic function in type 2 patients.