First of all, it sounds like you are making excellent decisions for your health after your recent heart attack. Hopefully this will help you remain healthy for years to come. Your question is an excellent one, and you are very much correct that there is a connection. You should definitely discuss your concerns with your cardiologist
A heart attack is the most dreaded complication of atherosclerosis, and for the vast majority of patients, especially those at your age, atherosclerotic coronary artery disease is the underlying cause of heart attacks. In simple terms, atherosclerosis is a buildup of plaque on the inside walls of any artery, including the coronary arteries that supply blood to the heart. When one of these plaques accumulates to the point that it blocks blood flow, the heart muscle downstream of the blockage does not get enough blood or oxygen, sometimes causing a heart attack. In addition, sometimes plaques that don't completely block an artery can rupture, spilling their contents into the blood vessel space and causing a blockage. Finally, a partially obstructing plaque can also serve as the foundation for a blood clot that can also cause a blockage. Cholesterol is a principle component of the atherosclerotic plaques, so even though you have been watching your diet and exercise in the last year, atherosclerosis is a condition that builds up over years and years, including the decades prior to your heart attack.
Any further questions you have can undoubtedly be answered by your cardiologist. It is very important to follow his or her recommendations to help preserve your heart function now that you have recovered so well and are motivated to improve your health habits!