1.   But further tests revealed significant blockages in three coronary arteries that, if left untreated, would probably have caused a major heart attack, doctors said.

2.   Further testing found significant blockages in three coronary arteries that, if left untreated, almost certainly would have caused a major heart attack.

3.   Still, there appeared to be significant arterial blockages that were depriving his heart muscle of adequate blood flow.

4.   When significant blockages occur, doctors often seek to remove them through angioplasty, in which a balloon-tipped catheter is inserted to remove the blockage.