Assessment of LV systolic function in atrial fibrillation using an index of preceding cardiac cycles

Sections of 1 Cardiovascular Imaging and 2 Electrophysiology, Department of Cardiology, Cleveland Clinic Foundation, Cleveland, Ohio 44195 The clinical assessment of left ventricular (LV) systolic function during atrial fibrillation (AF) is unreliable and difficult because of beat-to-beat variability. We evaluated an index for the estimation of LV systolic function in AF that is based on the relationship between the preceding (R-R 1 ) and prepreceding (R-R 2 ) R-R intervals. LV Doppler stroke volume (SV), ejection fraction (EF), peak aortic flow rate (AoF) and the maximum value of the first derivative of the LV pressure curve (dP/d t max ) were evaluated in 13 healthy open-chest dogs during triggered AF. All parameters showed a significantly strong positive linear relationship with the ratio of R-R 1 /R-R 2 ( r = 0.65, 0.74, 0.75, and 0.70 for SV, EF, AoF, and dP/d t max , respectively). The calculated value of LV systolic parameters at R-R 1 /R-R 2 = 1 in the linear regression line showed a good relationship and an agreement with the measured average value of the parameter over all cardiac cycles (SV, 12.1 vs. 12.8 ml; EF, 49.6 vs. 51.2%; AoF, 1.37 vs. 1.48 l/min; and dP/d t max , 2,323 vs. 2,454 mmHg/s). Using the LV systolic parameters estimated at R-R 1 /R-R 2 = 1 in the linear regression line allows the LV contractile function to be accurately and reproducibly evaluated during AF and obviates the less-reliable process of averaging multiple cardiac cycles. preload; afterload; contractility; R-R interval; echocardiography; left ventricular