Inappropriate sinus tachycardia-induced cardiomyopathy during pregnancy and successful treatment with ivabradine

A 32-year-old patient, in the 17th week of her first pregnancy, was admitted to the local hospital with complaints of palpitations and shortness of breath, which progressed over a month. The patient had no prior history of any cardiac disease. At the time of admission, the electrocardiogram (ECG) of the patient revealed that she had supraventricular tachycardia. When the patient did not respond to adenosine and electrical cardioversion, she was transferred to our hospital. ECG revealed IST with a heart rate (HR) of 152 bpm (Fig. 1a). She was continuously monitored, and intravenous esmolol infusion and oral metoprolol were started. Due to the high HR, verapamil (240 mg/day) and digoxin (0.25 mg/ day) were added, and HR decreased to 120 bpm (Fig. 1b). Echocardiography showed normal left ventricular (LV) dimensions, LV ejection fraction (LVEF) at 45%, and mild mitral regurgitation (MR). On the 7th day of hospitalization, LVEF decreased to 40%, followed by a decrease to 30% at the end of the 2nd week. The patient developed severe MR. Furosemide was added to the treatment, but the patient did not experience clinical relief. After receiving the patient’s consent, we began ivabradine treatment (2x5 mg), and the patient’s HR dropped to 90 bpm (Fig. 1c) and remained normal until discharge (Fig. 1d). Prior to ivabradine treatment, fetal echocardiography showed the fetal HR to be 156 bpm (Fig. 2a). After the 1st day of ivabradine treatment, the fetal HR was 150 bpm (Fig. 2b), and on the 7th day, it was 148 bpm (Fig. 2c). However, it did not decline further until delivery. When the patient’s HR returned to normal, LVEF improved each day and reached 50% and MR reduced. Maternal tachycardia and fetal bradycardia were not detected during the monthly follow-ups. A healthy baby boy was delivered. The baby was only fed with breast milk, and on 15th day, ECG showed sinus rhythm with an HR of 180 bpm (Fig. 2d).