Interval-dependent potentiation of left ventricular contractility is preserved in patients with atrial fibrillation and depressed ejection fraction

The relation between left ventricular systolic function parameters and preceding or prepreceding beat-to-beat distance in patients with atrial fibrillation: an echocardiographic study

We aimed at investigating the relation between left ventricle (LV) systolic parameters and beat-to-beat distances and also whether this relation is different in heart failure with reduced ejection fraction (HFrEF) patients with atrial fibrillation (AF). The relation between peak velocity in left ventricular outflow (V_LVOT), left atrioventricular plane displacement (LAVPD) or peak systolic tissue Doppler velocity of lateral mitral annulus (Lateral S') and preceding beat-to-beat distance (RR₁) or prepreceding beat-to-beat distance (RR₂) were analyzed by linear regression analysis. From this analysis, three parameters were obtained: slope of regression line, constant of regression line, and square of regression coefficient (r²) of linear relation. In the group with HFrEF, the slope and r² values of the regression line showing the relationship between the RR₁ interval and V_LVOT, LAVPD, and Lateral S' values were higher and the constants were lower. In the Kendall rank correlation analysis, the slope, constant, and r² values of the regression analysis between RR₁ interval and V_LVOT or Lateral S' were in significant correlation with LVEF. The r² of V_LVOT-RR₁ analysis, slope of this analysis, and slope of Lateral S'-RR₁ regression line values were mostly predictive for detecting HFrEF. It was concluded that the novel parameters obtained by linear regression analysis between LV systolic function parameters and RR₁ interval, but not RR₂, might be beneficial for evaluating systolic heart failure in patients with AF. They might have potential for future research about the physiopathology of heart and prognosis in patient with AF.

Refinement on single-beat determination of left ventricular systolic function in patients with atrial fibrillation

Single-beat determination of left ventricular systolic function at a beat with equal subsequent cardiac cycles has been proposed as an accurate method in atrial fibrillation. However, there has still been substantial variability between the values calculated from beats with equal subsequent cycles. Therefore, some refinement on the single-beat method is needed. In 100 patients with atrial fibrillation, Doppler aortic flow time-velocity integral was determined for at least 20 consecutive cardiac cycles. The values at beats with equal subsequent cardiac cycles were chosen and compared with the average values over all cardiac cycles. The values at beats with cycle lengths shorter than 500 milliseconds were usually far below the average values over all cardiac cycles. Bland-Altman agreement analysis revealed improved accuracy by gradually narrowing the range of the limits of agreement when 2 or 3 beats with equal subsequent cycles and cycle lengths longer than 500 milliseconds were used for evaluation.

Assessment of left ventricular systolic function in patients with chronic atrial fibrillation and dilated cardiomyopathy using the ratio of preceding to prepreceding R–R intervals

The objective of this study was to determine the relation between left ventricular (LV) systolic function and the ratio of preceding (RR1) to prepreceding (RR2) R-R intervals in patients with chronic atrial fibrillation (AF) and dilated cardiomyopathy. LV systolic function (Emax) was examined using a conductance catheter with a micromanometer in 13 patients with chronic AF and dilated cardiomyopathy. We calculated Emax as a load-independent index of LV contractility and compared it with RR1, RR2, and the ratio of RR1/RR2. We analyzed 50+/-13 cardiac cycles (range 18-61) in each patient. Average heart rate was 80+/-13 beats/min, and ejection fraction over all cardiac cycle in each patient measured by conductance catheter was 31+/-8%. Emax was positively correlated with RR1 and RR1/RR2 in all patients, and negatively correlated with RR2 in all patients. In each patient, correlation coefficients of Emax with RR1/RR2 were greater than those with either RR1 or RR2. Furthermore, Emax at RR1/RR2=1 in the linear regression line reflected average Emax over all cardiac cycles in each patient. In conclusion, we have shown that LV contractility correlated positively with RR1/RR2 in patients with chronic AF and dilated cardiomyopathy, and LV contractility at RR1/RR2=1 represents the average value of contractility over all cardiac cycles.

Biplane assessment of left ventricular function during atrial fibrillation at beats with equal subsequent cycles

BACKGROUND

Prior study has demonstrated that the biplane single-beat method could be used to assess left ventricular function during atrial fibrillation at a beat with equal subsequent cycles. The study was to test whether we could improve the method by measuring a few beats with equal subsequent cycles and cycle-length limits.

METHODS

In 75 patients with atrial fibrillation, stroke volume and ejection fraction were determined from simultaneous biplane views of left ventricle for 20 beats using a matrix-array transducer and a biplane Simpson's rule. The influence of cycle lengths on the values of systolic parameters at beats with equal subsequent cycles was examined from the plot of normalized parameters (measured values/average values) against cycle lengths. The values of 1 to 3 beats with equal subsequent cycles and cycle-length limits were averaged and compared with the average values over 20 beats by Bland-Altman and mean percentage difference analysis. The variability of repeat measurements was evaluated in 10 patients.

RESULTS

The systolic parameters measured at beats with cycle lengths shorter than 500 ms were usually far below the average values. Agreement and mean percentage difference analysis revealed improved accuracy when 2 or 3 beats with cycle-length limits (>500 ms) were used for assessment. As the variability of averaging 2 or 3 beats is no greater than that of repeat measurements, both methods are equally good.

CONCLUSIONS

Accurate assessment of left ventricular systolic function in atrial fibrillation can be obtained by averaging 2 beats with equal subsequent cycles and cycle-length limits (>500 ms).

New parameters for left ventricular function in atrial fibrillation: based on the relationship between RR interval and performance

This study was designed to obtain new parameters representing left ventricular (LV) function independent of irregular RR intervals in atrial fibrillation (AF). AF patients were divided into Normal (n=9) and LV Dysfunction (n=9) groups. The relations between LV outflow peak ejection velocity (Vpe) and preceding (RR-1) or prepreceding RR intervals (RR-2) were obtained using logarithmic equations, from which the squared correlation coefficient (r2), slope, Vpe at RR-1 or RR-2=1 sec (Vpe-1), and the ratio of slope to Vpe-1 (Slope/Vpe-1) were calculated. Among the parameters between RR-1 and Vpe, Slope/Vpe-1 was higher in LV Dysfunction group than in Normal group (p=0.05). When only coordinates with RR-1 from 0.6 to 1 sec were included, Slope/Vpe-1 (p=0.001) was higher in LV Dysfunction group than in Normal group. Among the parameters between RR-2 and Vpe, Slope/Vpe-1, slope, and r2 were different between the two groups. In multivariate analysis, Slope/Vpe-1 between RR-2 and Vpe was only independent parameter. However, Slope/Vpe-1 between RR-1 and Vpe in the coordinates with RR-1 from 0.6 to 1 sec had the highest discriminating power. New parameters derived from the relations between RR intervals and LV performance might be useful to evaluate LV function quantitatively in AF.

Simultaneous biplane single-beat assessment of left ventricular systolic function in patients with atrial fibrillation

Left ventricular systolic function was studied in 40 patients with atrial fibrillation using a matrix-array transducer, which enables 2 simultaneous orthogonal views to be obtained in a biplane mode. Bland-Altman analysis showed excellent correlation and agreement between the systolic parameters of a single beat with identical RR1 and RR2 intervals and the measured average value over all cardiac cycles.

The prevalence of various arrhythmias in normotensive and hypertensive elderly patients

The prevalence of the most frequent arrhythmias was studied in a geriatric day hospital. Patients older than 65 years have been considered, of them 118 were normotensive and 56 hypertensive subjects. Comparison of the two groups revealed no statistically significant difference either in the frequency of occurrence or in the type of arrhythmias. Dividing the hypertensive patients in the Lown's classes, only those of class 3 or over displayed a considerably higher frequency of arrhythmias than the normotensive subjects. The results demonstrate the age-dependent increase of the prevalence of arrhythmias in general, and the increased occurrence of complex ventricular types in the hypertensive subjects.

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

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-R1) and prepreceding (R-R2) 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/dt(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-R1/R-R2 (r = 0.65, 0.74, 0.75, and 0.70 for SV, EF, AoF, and dP/dt(max), respectively). The calculated value of LV systolic parameters at R-R1/R-R2 = 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/dt(max), 2,323 vs. 2,454 mmHg/s). Using the LV systolic parameters estimated at R-R1/R-R2 = 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.