A 38-year-old European woman with type I diabetes mellitus and corrected hypothyroidism and negative family history of dysrhythmias or cardiomyopathies was first noted to have a persistent asymptomatic tachycardia ∼110–120 b.p.m. during the third trimester of her first pregnancy. The 12-lead electrocardiogram (ECG) at the time confirmed P-wave morphology consistent with a sinus tachycardia with normal intrinsic atrioventricular conduction and narrow QRS complex. Reversible causes were ruled out and the tachycardia was attributed to the pregnant state. After delivery of her first son, the tachycardia persisted postpartum over several months and she was referred to Cardiology for suspected inappropriate sinus tachycardia. Apart from the elevated heart rate the physical exam was normal. A transthoracic echocardiogram (TTE) 8 months after delivery demonstrated a dilated left ventricle (LV) with severely impaired function [ejection fraction (EF) 15%], presence of an apical thrombus and an interatrial shunt. A cardiac magnetic resonance imaging (MRI) confirmed the echocardiographic findings and additionally diagnosed an ischaemic scar in the apex () but coronaries were unobstructed on ECG-gated computed tomography coronary angiogram. A genetic screen within the 100 000 Genomes project did not reveal any abnormalities in the 84 genes associated with dilated cardiomyopathy known at the time. The main differential diagnosis was a late diagnosis of peripartum cardiomyopathy with secondary LV thrombus formation complicated by embolic myocardial infarction, or myocarditis and a paradoxical coronary embolic event facilitated by the interatrial defect. With optimal medical heart failure therapy and Warfarin the left ventricular function fully recovered, the left ventricular thrombus resolved completely, and heart rate normalized within 6 months. A persistent foramen ovale closure was performed after recovery of LV function and thrombus resolution based on the differential diagnosis of paradoxical embolism. Warfarin was ceased. An attempt to wean the heart failure medication resulted in progressive LV dilatation (as documented in a routine follow-up cardiac MRI) within 3 months after stopping her betablocker and angiotensin-converting enzyme-inhibitor (ACEI) and were therefore reinstituted. The patient remained asymptomatic throughout.\nThree years later the patient became pregnant with her second child, requiring suspension of ACEI therapy. Bisoprolol was continued and she was closely monitored with clinical and echo surveillance by the Pregnancy Heart Team. Towards the beginning of the third trimester, the patient noted palpitations and a repeated TTE found a mildly impaired left ventricular EF of 46% (compared to previously 57%) and a heart rate of 120 b.p.m. No overt clinical signs of heart failure were present. The 12-lead ECG () demonstrated a regular organized atrial rhythm with 1:1 conduction to the ventricles with discrete monomorphic P waves separated by isoelectric intervals with upright P waves in the inferior leads, negative in aVL and I, and biphasic negative–positive in V1–V2. The electrocardiographical features were consistent with a left-sided FAT with suspected origin from the superior mitral annulus using the Kistler algorithm. A further up-titration of Bisoprolol to maximum dose failed to control her heart rate, worsened her fatigue, and caused loss of hypoglycaemia awareness.\nGiven the deterioration in LV function in the context of a persistent atrial tachycardia and the previous cardiomyopathy during her first pregnancy, treatment to rate control the arrhythmia was mandated; however, options in this circumstance were limited by the safety profile of commonly used antiarrhythmic drugs. Ivabradine was discussed considering the higher incidence of autonomic FATs during pregnancy and the recent evidence of its efficiency in this particular subset of arrhythmias. In view of the limited available data regarding the teratogenic risk of ivabradine, this option was reviewed with the Pregnancy Heart Team and pharmacists, as well as the patient. It was felt that the benefits would outweigh the risks and ivabradine was started at a dose of 5 mg twice daily. A three-lead 24 h Holter ECG was fitted and recording started parallel to commencing the treatment. The effect was observed ∼6 h after the first dose with a successful reduction of the average heart rate to ∼100 b.p.m. (). Ivabradine was further increased to the target dose of 7.5 mg twice daily. A repeated TTE under improved rate control demonstrated an improved left ventricular function (LV EF 55%).\nThe patient was scheduled for obstetric foetal ultrasound scans at gestation Weeks 28, 32, and 36, which revealed no abnormalities, and had an uncomplicated vaginal delivery of a 3900 g healthy male infant at term. A 12-lead ECG 1 month postpartum showed spontaneous resolution of the atrial tachycardia and confirmed normal sinus rhythm. Ivabradine was stopped and her betablocker continued. The ACEI has been reinstituted after the pregnancy. She has been symptom free since delivery.
A 2-year-6-month-old girl was transferred to our hospital from a primary care center for the management of tachyarrhythmia. Eight months prior to her presentation, she was found to have an increased heart rate (HR) of around 200 bpm on routine physical examination. At that time she was asymptomatic and her echocardiography was normal. Nevertheless, a week prior to her presentation to our center, an increased HR of 190 bpm was noted again on routine exam. Repeat echocardiography revealed LV dilatation along with a reduced LV systolic ejection fraction of 35%. ECG showed supraventricular tachycardia (SVT), namely atrial tachycardia. She failed a trial of adenosine and responded weakly to metoprolol. The patient was discharged on metoprolol 25 mg/day divided into two doses. She presented 2 days later to the same hospital. She had a HR of 250 bpm. She received two doses of adenosine, one dose of amiodarone and several doses of flecainide during her admission. However, no improvement was noted after 5 days of treatment, and also after direct current cardioversion. She was then transferred to our center for adequate rate control and appropriate investigation.\nUpon admission to our PICU, HR was 190 bpm. On examination, she was pale, tachypneic and hypoactive, but responsive to verbal stimulation. A third heart sound was noted on cardiac auscultation. Additionally, she had cool extremities and palpable hepatomegaly. Echocardiography was repeated, it showed worsened LV dilatation and severe LV systolic dysfunction (EF was around 20%), and moderate mitral regurgitation (see ). ECG revealed an atrial tachycardic rhythm. Patient was given adenosine. She received a second higher dose of adenosine and an infusion of amiodarone. She failed to respond adequately to these medications. Consequently, the patient was started on ivabradine at 0.15 mg/kg/day. An adequate response was noted few hours after the first dose of ivabradine. HR decreased to 90 bpm and she reverted to sinus rhythm. shows the patient's ECG pre- and post-ivabradine. The dose of ivabradine was adjusted to 0.033 mg/kg thrice daily. Adequate response was noted and the patient was discharged on ivabradine.\nOne month after the discharge, she presented to our clinic and was found to have a normocardic sinus rhythm on ECG, and an improved cardiac function on echocardiography (EF of 50%). In short, this is a case of SVT-induced DCM managed appropriately with ivabradine.