Conduction of electrical signals across the affected tissue

Blood flow through the coronary arteries is unrelated to electrical signals. The electrical signals are passed through the specialized cells of the heart muscle and not in the coronary arteries. The coronary arteries on the outside of the heart provide blood to the heart muscle (oxygen and nutrition), which is so thick that the middle and outside of the muscle cannot get enough oxygen and nutrition from the blood flowing through the heart. If the coronary arteries are blocked, and no oxygen or nutrition gets to an area of the heart muscle supplied by the coronary arteries, the heart muscle in that area dies and is unable to contract first becoming flaccid and floppy and then turning into a scar- a HEART ATTACK. The heart muscle cells then may not be able to conduct the electrical impulses properly. Surrounding areas may not beat properly and the heart contraction may become uncoordinated. This can lead to heart fibrillation and death, or if the area is small and not essential to conduction of the electrical signals maybe only minor arrythmias or no problem at all. 

This depends on what portion of the heart the blood supply is reduced to. Generally reduced cardiac circulation to the heart affects adversely electrical activity of the heart but not invariably. Hearts which have stopped pumping blood can have remarkably normal electrical conduction.