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

BACKGROUND: Cardiac resynchronization therapy (CRT) is characterized by a approximately 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. METHODS: Thirty-four CRT candidates were haemodynamically evaluated by pressure-volume loop analysis during biventricular pacing. RESULTS: 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. CONCLUSION: Although both parameters display an average increase during pacing, the change relative to baseline values of SW and dP/dt(max) is not related.