Men and women are known to react differently to stress. Thus, stress cardiomyopathy almost solely strikes women. Stress cardiomyopathy is suggested to relate to sex differences in catecholamine reaction. Left heart function during dobutamine stress is well described, but sex-specific inotropic and lusitropic response to abrupt termination of dobutamine stress is not. We aimed to investigate sex differences in left ventricular (LV) and atrial (LA) function during and after dobutamine stress. We enrolled 20 healthy elderly subjects (60-70 yr, 10 females) and measured their LV and LA volumes throughout the cardiac cycle by cardiac magnetic resonance imaging at rest, during dobutamine stress (15 μg·kg(-1)·min(-1)), 15 min after termination (T15), and 30 min after termination (T30) of dobutamine stress. We calculated LV ejection fractions, LV stroke volumes, LV peak filling rates, and LA passive, active, and conduit volumes. Sex differences were not observed at rest or during dobutamine stress. Compared with prestress values, at T15 a rebound decrease in LV peak filling rate was observed in women (-22 ± 3%, P < 0.001) but not in men. This was reflected in reduced LA passive emptying volume (-40 ± 3%, P < 0.001) and a corresponding increase in LA active emptying volume (36 ± 2%, P < 0.001). At T30 there were no differences between the sexes. We conclude that dobutamine causes greater stress to the female heart. This is revealed after termination of dobutamine stress where the left heart recovers in men, whereas women experience rebound LV stiffening with reduced diastolic relaxation. This is the first report of a sex-specific transient rebound phenomenon in cardiovascular response to catecholamines.
Keywords: diastolic function; dobutamine stress; rebound effect; stress cMRI.