Sinus node is the electrical high command of our heart .When it gets injured seriously (or shot down as in sinus arrest ) there is utter chaos in the lower ranks !
This is what happened in this patient .
The lower pacemkers can either passively release themselves as escape rhythm or actively fire with a ectopic focus . Any combination of escape / ectopic beats can occur .If occasional sinus beats capture the ventricles things can become further complicated .
It is obvious , this random intra-cardiac shooting makes the life of the myocardium miserable . It is a perfect setting for syncope, tachcyardic cardio myopathy , extreme brady induced VT , VF even SCD.
*Meanwhile , It is heartening to note SND rarely lead to sudden death in spite of all the chaos .However extreme bradycardias that occur in complete heart block does not enjoy this immunity as fatal complications are common if not intervened .