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.
A 30 day old boy weighing 3 kg was referred to our pediatric intensive care unit in view of significant respiratory distress and cardiogenic shock. Physical examination revealed tachycardia (200bpm), and tachypnoea with decreased pulses and poor peripheral perfusion. Blood gas showed severe metabolic acidosis (pH 6.9; HCO3 3.6 mol/L; PCO2 15mmHg). The baby was resuscitated with intravenous fluid and sodium bicarbonate correction.The 12-lead electrocardiogram (ECG) showed a regular narrow QRS tachycardia with a rapid ventricular rate of 187 bpm with long RP interval and abnormal peaked P wave morphology.The P waves were biphasic in V1 and positive in leads II, III and aVF suggestive of EAT []. Chest radiograph showed a cardiothoracic ratio of 75%. Echocardiography showed severe left ventricular (LV) dysfunction [ejection fraction (EF) 19%] with significant LV dilatation [LVIDd 2.5cm (Z score +3.18)]. SARS-CoV-2 PCR was negative and antibodies levels were normal. Adenosine given during the tachycardia, resulted in transient termination of the tachyarrhythmia followed by reappearance []. Enteral ivabradine (0.15mg/kg) was given resulting in gradual reduction of heart rate one hour after initiation and the rhythm became sinus after 4 hours. Enteral digoxin (10mcg/kg/day) was added one hour after ivabradine. There was significant improvement in the hemodynamics and perfusion (mean BP 25 mmHg). Blood gas after stabilization revealed improvement in the metabolic acidosis (pH 7.49; HCO3 16.6 mol/L; PCO2 22mmHg). However the respiratory distress and LV dysfunction persisted. Supportive care including bubble continuous positive airway pressure, milrinone and furosemide infusion were provided for the LV dysfunction. He symptomatically improved with supportive care and it was weaned off after 24 hours. LV dimension [LVIDd 1.6cm (Z score -1.29)] and function (EF 55%) improved significantly after 72 hours. He was discharged after 5 days of hospitalization on oral ivabradine (0.15mg/kg twice a day), and digoxin (5mcg/kg twice a day). The timeline of events which happened during the first 72 hours isshown in the .