Features of autonomic regulation of heart rate in patients with takotsubo syndrome

BACKGROUND: The pathophysiological mechanisms underlying takotsubo syndrome are still being actively investigated, but it is generally accepted that sympathetic nervous system hyperactivity is of key importance. The method for assessing heart rate variability allows to study the vegetative status of a patient, however, there are few scientific works on this topic at present, and the results obtained are ambiguous.

AIM: To study heart rate variability in patients with takotsubo syndrome in acute and late periods of the disease at rest, when performing vegetative tests (the deep-breath test, active orthostatic test), as well as before and after mental stress tests and to compare the data obtained with the results of the examination of the control group.

MATERIALS AND METHODS: The study included patients with takotsubo syndrome (n = 48), including 43 (89.6%) women; the average age of the patients was 63.3 ± 13.5 years, and healthy volunteers of the same sex and age (control group, n = 40). All the subjects with takotsubo syndrome in the acute (first 7–14 days from the onset of the disease) and in the long-term periods of the disease (after 1 year and 2 years) and the ones in the control group underwent cardiorhythmography at rest to assess the heart rate variability after mental stress tests and against the background of vegetative tests.

RESULTS: According to the cardiorhythmography at rest, in 47 (97.9%) patients with takotsubo syndrome, the influence of sympathetic nervous system on the heart rate prevailed, which persisted in the long-term period of the disease. The vegetative tests revealed a paradoxical reaction of the sympathetic nervous system and reduced activity of the parasympathetic nervous system in the acute and late periods of takotsubo syndrome, compared with the control group. In the acute and long-term periods in the patients with takotsubo syndrome after mental stress tests, in comparison with control group, there was no increase in parasympathetic nervous system activity.

CONCLUSIONS: According to the study findings, the patients with takotsubo syndrome revealed autonomic dysfunction in the form of an excessive increase in the activity of the sympathetic nervous system both before the onset of the disease, and in the acute and long-term periods as well as a decrease in vagal tone, which was reflected in the suppressed response of the parasympathetic nervous system to the deep-breath test and mental stress tests.