Investigators from Finland have found that individuals under age 40 who smoke tobacco products have a five times higher chance of having a myocardial infarction (heart attack) than nonsmokers, and that smoking is the single most important cause of heart attacks in younger patients. Their results were published in the September issue of Tobacco Control.
They reached this conclusion by examining data from the World Health Organization Multinational Monitoring of Trends and Determinants in Cardiovascular Disease (MONICA) database. In the MONICA project, information was collected on cardiac risk factors and subsequent cardiac "events" in populations of individuals from 21 countries in the 1980s and 1990s. It turned out that, of younger patients (less than 40 years of age) who had heart attacks, 80% were smokers. Furthermore, smoking was the only risk factor identified in over half of these young heart attack victims.
Since not all smokers younger than 40 have heart attacks, it is likely that many of these young heart attack patients have some unidentified risk factor -perhaps a clotting disorder or unidentified hypercholesterolemia - that predisposes them to premature cardiovascular disease. Under this theory, smoking would greatly accelerate effects of such risk factors, such that cardiac disease occurs more "prematurely" than it otherwise would.
This is nothing new, of course. Smoking greatly accelerates atherosclerosis ("hardening of the arteries") in anybody, of any age. Thus, even smokers who survive past 40 without overt cardiac disease are very likely to develop heart attacks or strokes years - or even decades - earlier than they otherwise might.