Determination of the Target Ventricular Rate

In a pilot study, we determined the target ventricular rate of patients with atrial fibrillation by evaluating their ventriculoarterial coupling. Eleven patients with atrial fibrillation were studied. We recorded M-mode echocardiograms and radial artery blood pressure simultaneously. The left ventricular end-systolic pressure-volume ratio (Emax) and effective arterial elastance (Ea) were calculated for each beat, and the relationship of the preceding R-R interval (pRR) to Emax and Ea was evaluated. There was a significant positive correlation between pRR and Emax, and a significant negative correlation between pRR and Ea in all patients. The pRR that produced maximal stroke work was determined at the point of Emax=Ea, and the pRR that achieved maximal mechanical efficiency was determined at the point of 2Ea=Emax. By evaluating ventriculoarterial coupling in these patients who had atrial fibrillation, we were able to determine that the range between the 2 pRR intervals was the range of the optimal ventricular rate. A narrower range of the 2 pRR intervals was observed in patients with dilated cardiomyopathy than in the patients with no underlying cardiac disease. We conclude that it may be possible to determine the optimal ventricular rate in patients with atrial fibrillation by evaluating ventriculoarterial coupling. (Tex Heart Inst J 2002;29:100–4)