How much does the risk of myocardial infarction (MI) decrease immediately after quitting smoking?

When an individual quits smoking, the risk of myocardial infarction (MI) begins to decrease almost immediately. Initial studies have shown that within the first 24 hours after quitting, the risk can decrease significantly, approximately by 50%. This immediate reduction is primarily due to improved cardiovascular function and decreased heart rate, which are directly impacted by the cessation of nicotine and other harmful substances found in cigarettes.

Over time, as the body continues to heal and recover from the damage caused by smoking, the risk of MI continues to decline further. However, the most substantial improvement in risk occurs right after quitting, which is why a 50% risk reduction is variable yet consistently supported by several epidemiological studies.

Other percentages presented reflect subsequent risk reductions over longer periods but do not accurately characterize the immediate effect seen within the first day after quitting smoking. The understanding of how quickly and effectively the body begins to repair itself emphasizes the importance of quitting smoking as a vital step in reducing cardiovascular risk.