Dear Dr. My son is 12 years old and until recently very healthy. Here is his 24 hours holter monitor report:       1)     24 hours recording 2)     Symptoms: none 3)     Normal minimum, maximum and average heart rate for age 4)     HR variability beat- to-beat and day-night qualitatively normal 5)     Atrio-ventricular conduction: no abnormalities 6)     Supraventricular arrhythmia: none 7)     Pauses: no significant 8)     Ventricular arrhythmia: frequent LBBB PVC (9%) probably originating in the LVOT with rather narrow QRS complex. One PVC of different morphology. Wide QRS coupling interval. 9)     12 lead ECG: sinus rhythm with frequent LBBB PVSs with right inferior axis originating probably in the LVOF Summary: Frequent PVCs originating probably in the LVOT. Echocardiogram shows no abnormalities so far. Now my DR. pediatrician-cardiologist recommends further testing with Cardiac MRI and stress test. She wants to exclude Arrhythmogenic right ventricular dysplasia. I do not understand why and do not see connection Between holter monitor report and further investigation. I also understand that MRI is just 50% reliable in diagnosis of Arrhythmogenic right ventricular dysplasia. Can you please tell me more about my son’s findings? Thank you very much in advance.