Stroke work or systolic dP/dtmax to evaluate acute response to cardiac resynchronization therapy: are they interchangeable?

Cardiac resynchronization therapy (CRT) is characterized by a similar to 30% non-response. Invasive haemodynamic measurements are a traditional method to evaluate response to CRT. This study evaluates the correlation between acute changes in dP/dt(max) and Stroke Work (SW) during CRT. Thirty-four CRT candidates were haemodynamically evaluated by pressure-volume loop analysis during biventricular pacing. Mean dP/dt(max) and SW at baseline were 854 +/- 198 and 5186 +/- 2349, and displayed an increase during pacing of 106 +/- 117 mmHg/s (13% +/- 14%) and 1303 +/- 3039 mL/mmHg (30% +/- 52%), respectively. No correlation was found between the percentage change in dP/dt(max) and SW (R = 0.06, P = ns). When defining response an augmentation of 10% relative to baseline for both parameters, 16 patients demonstrated an ambiguous response. Although both parameters display an average increase during pacing, the change relative to baseline values of SW and dP/dt(max) is not related.