Rate response and cardiac resynchronisation therapy in chronic heart failure: higher cardiac output does not acutely improve exercise performance: a pilot trial.

Background: Rate adaptive pacing (RAP) during cardiac resynchronisation therapy (CRT) in patients with chronic heart failure (CHF) might improve exercise capacity through enhanced cardiac output (CO). Conversely, higher heart rates (HR) might set off a blunted force-frequency response (FFR).

Methods: Fourteen CRT-treated patients (62+/-3 years, left ventricular ejection fraction 30.