Inappropriate sinus tachycardia presented during pregnancy (clinical case)

Inappropriate sinus tachycardia (IST) is a sinus tachycardia unexplained by visible physiological and secondary causes with a resting heart rate of more than 100 beats per minute. The true prevalence of IST is unknown. At the same time, IST seems to be common in normal pregnancies, which causes significant difficulties in differential diagnosis and patient management. There is no practice of diagnosing IST in Russia. An analysis of the literature revealed no descriptions of clinical cases of IST in pregnant women in Russian publications and found only one report of IST in the review article.

The paper presents a clinical case of IST in a 33-year-old woman in the third trimester of pregnancy. The patient had sinus tachycardia with a heart rate of 180 beats per minute, accompanied by complaints of shortness of breath, weakness, and palpitations. During Holter monitoring, sinus tachycardia was recorded during both daytime and nighttime hours. A differential diagnosis with paroxysmal reciprocal sinus tachycardia and postural orthostatic tachycardia syndrome was performed. Other potential causes of sinus tachycardia were ruled out. The diagnosis of HCT has been established. Therapeutic options were limited due to pregnancy. Administration of metoprolol succinate at a dose of 25 mg produced only a modest reduction in heart rate to 120 beats per minute. At 38 weeks of gestation, delivery was performed via cesarean section. During dynamic follow-up 4 months after delivery, a decrease in tachycardia to 100 beats per minute was noted, which requires continued monitoring.

The features of the presented clinical case are the extremely high heart rate for the sinus rhythm described for the first time (180 beats per minute) and persistent moderate sinus tachycardia 4 months after delivery.

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