How relevant are premature ventricular contractions in idiopathic cardiac arrest ? are there any preceding symptoms ?

Gosh: U are jumping from a to z. I hope no one had cardiac arrest. Most people have some pvcs (extra beats or skip beats), usually harmless in absence of heart disease but can be aggravated by stress, caffeine, thyroid disease, or electrolyte imbalance. With heart disease, pvcs can trip off a serious rapid arrhythmia. Symptoms include palpitations, dizziness and fainting.

PVCs are common: Rarely PVC hitting badly in ekg in cycle can cause arrythmias including VT v fib.