A 9-year-old female, with a known medical history of severe dilated cardiomyopathy secondary to ectopic atrial tachycardia, presented to our clinic for a regular check-up. Echocardiography was significant for severe left ventricular (LV) dilatation, markedly reduced LV systolic function reflected by an ejection fraction of 30%, and severe mitral regurgitation. ECG revealed a regular sinus rhythm. Despite being on several medications including aspirin, carvedilol, digoxin, enalapril, and spironolactone, the patient's cardiac condition failed to improve. A gradual worsening in the systolic function of LV and the degree of mitral regurgitation was noted over the last few visits.\nUpon follow up, echocardiography findings were similar to the previous findings. However, ECG was significant for ectopic atrial tachycardia. We placed a 24-h Holter monitor a week after to evaluate appropriately her heart rhythm. Holter revealed an incessant atrial tachycardia interrupted by a few sinus beats.\nConsequently, the patient was admitted to the pediatric intensive care unit (PICU) for observation and initiation of appropriate anti-arrhythmic medications. Upon admission, carvedilol and digoxin were stopped and she was started on ivabradine at a dose of 0.025 mg/kg/day. Two hours after this first dose, she reverted to sinus rhythm (). The dose of ivabradine was increased gradually to 0.1 mg/kg/day. Reversal from atrial to sinus rhythm was observed a few hours after each dose. The effect of ivabradine was sustained for around 4–6 h. Given the suboptimal response to ivabradine, ivabradine was stopped and amiodarone was started for rhythm control. Nonetheless, during this hospital stay, a mild improvement in LV systolic function was noted on echocardiography (see ). Similarly, no side effects were attributed to the use of ivabradine. Her blood pressure remained within normal range, and she had no bradycardia or QT interval prolongation.\nThe patient cardiomyopathy was believed to be secondary to her incessant atrial tachyarrhythmia. Optimal control of rate and rhythm through medical or interventional therapies is the mainstay of DCM management in this case.
An one-year old girl presented a persistent tachycardia during a routine visit at the local pediatrician and was immediately transferred to KUNO university hospital. There had been a benign febrile infection 1 week prior to admission. Personal and family history was non-contributory to the tachycardia. Six months before, the previous check at the pediatrician had been uneventful. On admission she had mild signs of heart failure with delayed capillary refill time (3 s) and an enlarged liver. She had a tachycardia with 240 beats/min. Echocardiography showed structural normal anatomy with moderately reduced contractility while tachycardia. Laboratory studies including blood count, inflammatory biomarkers and cardiac troponin were normal but NT-proBNP was significantly elevated (maximum 2,685 pg/ml, lab reference <130 pg/ml).\nThe initial 12-lead electrocardiogram (ECG) showed a regular, sustained small-QRS-complex-tachycardia (mean heart-rate 240 beats/min). The tachycardia demonstrated a 1:1 atrio-ventricular conduction (P-P cycle length 250 ms) with a monomorphic P-wave configuration characterized by a superior axis (P-vector of −60°) and sinus tachycardia was therefore not possible. RP interval was significantly longer than PR—interval (i.e., long-RP-tachycardia) and we thought about a permanent orthodromic supraventricular tachycardia first (such as permanent junctional reciprocating tachycardia) () and gave Adenosine intravenously. This did not stop atrial tachycardia and ruled out a reentry-tachycardia dependent on the AV-node. We therefore hypothesized a focal ectopic atrial tachycardia. Infusion of Flecainide (1 mg/kg/30 min) did not affect the atrial rate or atrioventricular conduction. Synchronized electric cardioversion with 0.5 and 1 J/kg was performed due to signs of hemodynamic instability but this just interrupted the tachycardia for seconds. Medical cardioversion and rate control were attempted starting Amiodarone with a bolus. After 30 min the girl developed a second-degree AV-block (type Wenckebach) with ongoing QRS-amplitude alternans, eventually resulting in a bradycardia with 70 beats/min. Amiodarone infusion was stopped and the AV-block resolved. While persisting EAT, Esmolol infusion was started and slowly increased to a maximum rate of 75 mcg/kg/min. This lowered the atrial tachycardia rate to 160 beats/min without affecting the blood pressure. Ivabradine was started with a dose of 0.25 mg (0.025 mg/kg) every 12 h and increased to 0.5 mg (0.05 mg/kg) per dose on the second day. This led to a persistent heart rate reduction to a physiologic level (80–100 beats/min at rest) with alternating periods of restored sinus rhythm and ectopic atrial rhythm. Subsequent ECG recordings showed sinus rhythms with regular AV conduction and no abnormalities of de- or repolarization (). No adverse effects attributable to Ivabradine were registered. After stabilization Esmolol infusion was discontinued and the beta-blocker therapy was switched to Metoprolol administered orally (1 mg/kg/d). Holter evaluation before discharge (1 week after admission) showed sinus rhythm with short times of ectopic atrial rhythm and a regular diurnal pattern and heart rate.\nIn the follow up visits 2 and 10 weeks later echocardiography showed normal left-ventricular function and dimension. The 12-lead-ECG and Holter evaluation showed alternating ectopic atrial and sinus rhythm with a physiologic diurnal heart rate spectrum and a regular response to physical activity (). Combination of Metoprolol and Ivabradine did not cause bradycardia and no other side effects attributable to medication were noticed.