Cardiac autonomic imbalance in patients with reversible ventricular dysfunction takotsubo cardiomyopathy

Abstract

Background: Although in reversible takotsubo cardiomyopathy (TC), wall motion generally recovers dramatically within a few weeks, there are few data on changes in autonomic function in this condition. Aim: To investigate cardiac autonomic function in the acute and chronic phases of TC. Methods: Ten patients with TC (mean age 70.1±13.7 years) underwent cardiac catheterization on the first hospital day, when left ventricular (LV) ejection fraction (EF) was calculated. A Holter electrocardiographic study was performed within 3 days after the onset of symptoms (0 months) and 3 months after discharge (3 months). The standard deviation of the mean cycle length of normal-normal R-R (NN) intervals over 24 h (SDNN), and the 24-h standard deviation of the mean value of the difference between the NN intervals for each 5-min segment (SDANN), were calculated according to time-area analysis of heart rate variability over 24 h. Frequency domain analysis was also done. Results: Coronary angiography in the acute and chronic phases revealed no significant stenosis in any TC patient. LV wall motion returned to normal in 17.6±6.4 days. LVEF was 45.7±8.8% in the acute phase and 69.8±6.8% after the improvement of wall motion (p < 0.001). Between 0 months and 3 months, SDNN and SDANN improved significantly, from 88.8±35.5 to 109.5±33.4 ms (p=0.01) and from 79.9±34.7 to 99.3±40.3 ms (p=0.03), respectively. No significant changes were observed in frequency domain parameters. Discussion: These results support our previous hypothesis that TC might be caused by neurogenic stunning of the myocardium, due to acute autonomic dysfunction. © The Author 2007. Published by Oxford University Press on behalf of the Association of Physicians. All rights reserved.