Here is the bottom line according to JAMA:
If you have had a heart attack, a stroke, a coronary stent, or coronary artery bypass graft surgery, you should keep taking aspirin. The new studies and guidelines do not affect the importance of this treatment for you.
If you have not had one of the above conditions or procedures and are older than 70 years, younger than 40 years, or at increased risk of bleeding because of a medical condition or medications, you should not take aspirin for primary prevention of heart disease.
If you are between 40 and 70 years old, at low risk of bleeding, and thought to be at high risk of heart disease, you might benefit from aspirin. This is an area where personal preferences matter. Talk to your doctor to help decide whether taking low-dose aspirin makes sense for you. Most healthy adults do not need aspirin.
Finally, beyond aspirin, continue to take other important steps to improve heart health and enjoy a longer, healthier life. Such steps include eating a healthy diet, exercising, not smoking, and controlling high cholesterol, high blood pressure, and diabetes.