Tachycardia-Induced Cardiomyopathy Due to Atrial Tachycardia During Pregnancy.

Focal atrial tachycardia is an ectopic rhythm that originates in the atrium. The occurrence of atrial tachycardia during pregnancy is uncommon in clinical practice. (The incidence is approximately 22 to 33 cases per 100,000 pregnancies.) This report presents a case of tachycardia-induced cardiomyopathy resulting from focal atrial tachycardia during pregnancy. A 28-year-old primigravida at 34 weeks and 6 days of gestation was admitted to the hospital due to progressive shortness of breath and palpitations that had persisted for 30 weeks, with worsening symptoms in the past day. At 28 weeks of gestation, an electrocardiogram indicated sinus tachycardia, and treatment with labetalol was ineffective in controlling the heart rate. Subsequent electrocardiogram findings indicated atrial tachycardia, and cardiac ultrasound examination revealed left ventricular enlargement with reduced contractile function (left ventricular ejection fraction of 20%). Laboratory testing showed an elevated N-terminal pro-B-type natriuretic peptide level of 5,572 pg/mL (reference value, <300 pg/mL). After a multidisciplinary assessment, the pregnancy heart team decided that there was no incremental benefit to continuing the pregnancy and the decision was made to perform a cesarean section at 34 weeks and 6 days. During the procedure, the patient experienced 2 episodes of cardiac arrest and underwent cardiopulmonary resuscitation. This case serves as a critical reminder that persistent, unexplained sinus tachycardia in pregnancy may mask underlying focal atrial tachycardia and portend a high risk for rapidly deteriorating tachycardia-induced cardiomyopathy, demanding vigilant evaluation and preemptive management strategies.