During what period of time could a stimulus to the heart cause a life-threatening arrhythmia?

Explanation:

In Elder years an arrhythmia could be cause to the heart by different reasons like a chronic organic heart disease or a congenital heart disease, or other disease obtained with passing time and bad habits.

It's important to know that this arrhythmia happens in weaker hearts, that's why in elder years is most probably to occur.

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