How can blocked coronary arteries lead to a myocardial infarction?

Myocardial infarction is said to occur when the amount of circulated blood that get to certain part of the heart decreases or blood did not get to those areas at all. This usually lead to the destruction of the heart muscles. Another term for myocardial infarction is heart attack. Myocardial infarction usually occur as a result of blocked coronary arteries. Coronary arteries are the ones responsible for supplying blood to the heart muscles. These coronary arteries can become narrowed or blocked as a results of atherosclerosis. When the arteries are blocked, it becomes impossible to get oxygenated blood to the heart and this leads to myocardial infarction.  

i think it is true in my reasonment ..

the answer is; comparing the frequency of collisions with and without the device

this makes the anti-collision system an independent variable and the collisions a dependent variable. if there are fewer collisions with an anti-collision system that without, then it can be stated that the system is a success. essentially, collisions under an anti-collision system are compared with the frequency of collisions by cars with the human drivers.