Beat to beat left ventricular performance in spontaneous atrial fibrillation does not depend on afterload

In the study by Brookes and colleagues, 2 the left ventricular systolic pressure (directly measured with catheter tip manometer) varied rather little during atrial fibrillation, which the authors attributed to clamping of the arterial systolic pressure by peripheral mechanisms. The argument that a limited variation of end systolicpressure in patients with atrial fibrillation (in our patient group the average ESP was 126 mm Hg and the average standard deviation of ESP was 13 mm Hg) is measured because arterial pressure is damped by baroreceptor and other reflex mechanisms, confirms in our opinion the observation thatafterload, which unites the above mentioned properties of the arterial system, changes from beat to beat.