Hemodynamic Optimization in CardiacResynchronization Therapy: ShouldWeAimfordP/dtmax or Stroke Work?

Abstract

This study evaluated the acute effect of dP/dtmax- versus stroke work (SW)-guided cardiac resynchronization therapy (CRT) optimization and the related acute hemodynamic changes to long-term CRT response. Hemodynamic optimization may increase benefit from CRT. Typically, maximal left ventricular (LV) pressure rise dP/dtmax is used as an index of ventricular performance. Alternatively, SW can be derived from pressure-volume (PV) loops. Forty-one patients underwent CRT implantation followed by invasive PV loop measurements. The stimulation protocol included 16 LV pacing configurations using each individual electrode of the quadripolar lead with 4 atrioventricular (AV) delays. Conventional CRT was defined as pacing from the distal electrode with an AV delay of approximately 120ms. Compared with conventional CRT, dP/dtmax-guided optimization resulted in a one-third additional dP/dtmax increase (17 ± 11% vs. 12 ± 9%; p<0.001). Similarly, SW-guided optimization resulted in a one-third additional SW increase (80 ± 55% vs. 53 ± 48%; p<0.001). Comparing both optimization strategies, dP/dtmax favored contractility (8± 12% vs. 5 ± 10%; p= 0.015), whereas SW optimization improved ventricular-arterial (VA) coupling (45% vs. 32%; p<0.001). After 6months, mean LV ejection fraction (LVEF) change was 10 ± 9% with 23 (56%) patients becoming super-responders to CRT (≥10% LVEF improvement). Although acute changes in SW were predictive for long-term CRT response (area under the curve: 0.78; p= 0.002), changes in dP/dtmax were not (area under the curve: 0.65; p= 0.112). PV-guided hemodynamic optimization in CRT results in approximately one-third SW improvement on top of conventional CRT, caused by a mechanism of enhanced VA coupling. In contrast, dP/dtmax optimization favored LV contractility. Ultimately, acute changes in SW showed larger predictive value for long-term CRT response compared with dP/dtmax.