Cardiac autonomic imbalance in patients with reversible ventricular dysfunction takotsubo cardiomyopathy

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.

To investigate cardiac autonomic function in the acute and chronic phases of TC.

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.

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.

These results support our previous hypothesis that TC might be caused by neurogenic stunning of the myocardium, due to acute autonomic dysfunction.