I had a cardiac mri done which showed thickening in my left ventricular. is there a chance i can have fatal arrhythmia because of this?

Maybe: You need to know if this is a concentric vs septal hypertrophy of the left ventricle. I will add an echocardiogram for better assessment of the dynamic of the heart. Also an ekg. Hypertension is a common secondary cause of hypertrophy of the left ventricle. It is associated with arrhythmias and sudden death. Go and see a cardiologist for better risk assessment.