Much media attention has been paid to the new guidelines from American College of Cardiology/American Heart Association (ACC/AHA) on the primary prevention of cardiovascular disease. Based on new clinical trial data, ACC/AHA no longer recommends that healthy adults without cardiovascular disease — emphasis on without cardiovascular disease — take daily aspirin for the primary prevention of cardiovascular disease.
This change, while significant, is highly nuanced and dependent on a clear understanding of the difference between primary prevention and secondary prevention. Primary prevention is the sum of efforts to prevent an event that an individual has never had in the past. An example of primary prevention is administration of vaccines, which help protect against contracting a disease in the first place. Secondary prevention involves reducing the impact of current diseases and seeking to prevent future recurrences of events that have already occurred. Quitting smoking after being diagnosed with chronic obstructive pulmonary disease (COPD) and completing cardiac rehabilitation after having a heart attack represent common examples of secondary prevention.
The new ACC/AHA guidelines address the primary prevention of cardiovascular disease in individuals currently without cardiovascular disease. For decades, the prevailing notion was that a low-dose aspirin may prevent cardiovascular disease before it begins. However, recent large randomized trials have shown this perceived benefit to be negligible while increasing the risk of a serious bleeding event. This was true even in individuals with diabetes who have an inherently higher risk for cardiovascular disease. Based on this new evidence, low-dose aspirin is no longer recommended for primary prevention in individuals at low risk for cardiovascular disease, adults older than age 70, or individuals at increased risk of bleeding.