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 RR1and 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.