Immediate impairment of left ventricular mechanical performance and force-frequency relation by rate-responsive dual-chamber, but not atrial pacing: Implications from intraventricular isovolumic relaxation flow

Despite the AV synchrony, right ventricular apical pacing immediately attenuates the left ventricular contraction and relaxation performance, which deteriorated further and suppressed the physiologically positive force-frequency relation after accelerated pacing rate.