Background and objectives: Irregular RR intervals in atrial fibrillation (AF) make beat-to-beat changes in left ventricular (LV) systolic performance. Early diastolic mitral annular velocity (E') is one of the well-established parameters for evaluating LV diastolic function. The relation between RR intervals and E's is unknown. The aim of this study was to observe the influence of continuous changes in RR interval on the parameter for diastolic function in AF.
Subjects and methods: Echocardiography was performed in 117 patients with AF. E' was adjusted for the effect of pre-preceding RR interval (RR-2) using the logarithmic equation between RR-2 and E'. The logarithmic equation between adjusted E' and preceding RR interval (RR-1) was calculated.
Results: The slope in the relation between RR-1 and E' varied from -2.5 to 2.6. The slope was lower (more likely negative) in patients with higher ratio of early diastolic mitral flow velocity (E) to E' (r=-0.21, p=0.023), ischemic heart disease (IHD, r=0.21, p=0.026), and higher systolic blood pressure (r=-0.19, p=0.046). When patients were divided into these 3 groups on the basis of slope, the lowest slope group (<-0.55, n=39) was associated with higher E'/E (p=0.004) and IHD (p=0.018) compared with the highest slope group (>0.57, n=39). The slope with regards to the relationship between RR-2 and E' also varied from -3.4 to 3.1.
Conclusion: Changes in RR intervals had variable effects on E's according to clinical variables in AF.
Keywords: Atrial fibrillation; Electrocardiography; Heart rate; Pulsed Doppler echocardiography; Ventricular function, left.