Abstract
Background
The syndrome of inappropriate sinus tachycardia (IST) is well recognized and affects ∼1% of the population. We believe IST in pregnancy is a relatively frequent yet under-recognized phenomenon that may represent a distinct arrhythmia. To date, there are only three case reports in the literature.
Purpose
To further understand the natural history of IST in pregnancy, and to explore maternal outcomes.
Methods
A retrospective, observational cohort analysis.
Results
19 pregnant women presented to our institute with a definitive diagnosis of IST (as defined by task force criteria) between January 2016 and January 2017. Symptom onset was 4–36 weeks gestation (mean 20 weeks). Of those in their second or subsequent pregnancy (n=8), 50% described symptoms compatible with IST in previous pregnancies. 42% attended the emergency department on ≥1 occasion with symptoms of IST. 32% required hospital admission. 26% required pharmacological therapy (beta-blockers in all). There were no maternal deaths, instances of heart failure or acute coronary syndrome, no thromboembolic or haemorrhagic complications during pregnancy. Rates of Caesarean section were similar to the background rate of our unit; however, rates of induction were notably elevated (58% vs 25%), with 55% of these women being induced purely for symptoms of IST. Following delivery, symptoms resolved within one week for 17 of the women in the cohort, 1 had symptoms resolve after 4 month and 1 had persistent symptoms as she became pregnant again.
Conclusion
IST in pregnancy likely represents a distinct arrhythmia; the majority of individuals here had symptoms only during pregnancy, which resolved rapidly postpartum. Additionally, half of the women in a second or subsequent pregnancy had suffered IST symptoms during previous pregnancies, with no symptoms in between pregnancies. It is biologically plausible and may represent an exaggerated cardio-autonomic response to the physiological changes of pregnancy such as increased sympathetic tone and change in baroreceptor reflex sensitivity. Recognition of the condition is important given it is associated with significant morbidity, the distressing nature of symptoms leading to high rates of hospitalization and induction of labour.
Funding Acknowledgement
Type of funding source: None
Inappropriate sinus tachycardia-induced cardiomyopathy during pregnancy and successful treatment with ivabradine
