BACKGROUND: The exact pathophysiology of Tako-Tsubo cardiomyopathy (TTC) remains unknown but a role for sympathetic hyperactivity has been suggested. Up to now, no direct evidence of sympathetic nerve hyperactivity has been established nor involvement of sympathetic baroreflex identified. The aim of our study was to determine, by direct sympathetic nerve activity (SNS) recording if sympathetic nervous system activity is increased and spontaneous baroreflex control of sympathetic activity reduced in patients with TTC. METHODS: We included 13 patients who presented with TTC and compared their SNS activity and spontaneous baroreflex control of sympathetic activity with that of 13 control patients with acutely decompensated chronic heart failure. SNS activity was evaluated by microneurography, a technique assessing muscle sympathetic nerve activity (MSNA). Spontaneous baroreflex control of sympathetic activity was evaluated as the absolute value of the slope of the regression line representing the relationship between spontaneous diastolic blood pressure values and concomitant SNS activity. Control patients were matched for age, sex, left ventricular ejection fraction and creatinine clearance. RESULTS: The mean age of the patients with TTC was 80 years, all patients were women. There were no significant differences between the two groups of patients for blood pressure, heart rate or oxygen saturation level. TTC patients presented a significant increase in sympathetic nerve activity (MSNA median 63.3 bursts/min [interquartile range 61.3 to 66.0] vs median 55.7 bursts/min [interquartile range 51.0 to 61.7]; p = 0.0089) and a decrease in spontaneous baroreflex control of sympathetic activity compared to matched control patients (spontaneous baroreflex control of sympathetic activity median 0.7%burst/mmHg [interquartile range 0.4 to 1.9] vs median 2.4%burst/mmHg [interquartile range 1.8 to 2.9]; p = 0.005). CONCLUSIONS: We report for the first time, through direct measurement of sympathetic nerve activity, that patients with TTC exhibit elevated SNS activity associated with a decrease in spontaneous baroreflex control of sympathetic activity. These data may explain the pathophysiology and clinical presentation of patient with TTC.