Influence of heart rate on stroke volume variability in atrial fibrillation patients with normal and impaired left ventricular function

Both resting tachycardia and irregular ventricular rhythm may contribute to impaired cardiac performance in atrial fibrillation (AF), This study asses ses the relation between resting heart rate and beat-to-beat changes in lef t ventricular (LV) ejection and filling in patients with normal and impaire d LV systolic function. Beat-to-beat variation in LV outflow and inflow vel ocity-time integral was measured using pulsed Doppler ultrasound in 39 pati ents with chronic AF and normal (n = 22) or impaired (n = 17) LV systolic f unction. Aortic velocity-time integral variability increased with mean hear t rate (p = 0.003) even though RR interval variability decreased (p < 0.001 ). Aortic velocity-time integral was more sensitive to the duration of both the preceding (p < 0.001) and prepreceding (p < 0.001) RR intervals at hig her heart rates, These relations were similar for patients with normal and impaired LV systolic function, The sensitivity of the filling velocity-time integral to RR interval variability also increased with heart rate (p < 0. 001). However, at higher heart rates the filling velocity-time integral (p 0.009) and filling time (p = 0.005) were less sensitive to change in RR int ervals in patients with impaired LV function, We conclude that beat-to-beat stroke volume variability in AF increases with heart rate. Stroke volume v ariability was not influenced by LV systolic function. (C) 1998 by Excerpta Medica, Inc.