Coronary Risk Factors
A 55-year-old man who smokes 30 cigarettes daily presents with one hour of retrosternal chest pain radiating to the neck. He has no diabetes or family history of premature coronary disease. Blood pressure is 128/78 mm Hg and body mass index is 26 kg/m². ECG shows 1 mm ST depression in leads II, III, and aVF, and troponin is elevated. Which factor contributed most to his coronary event?
- A.Cigarette smokingCorrect
- B.Male sex
- C.Age of 55 years
- D.Body mass index of 26 kg/m²
Explanation
Cigarette smoking is the single strongest modifiable contributor to coronary events in this patient; in the INTERHEART study current smoking carried an odds ratio of about 2.9 for myocardial infarction with a population attributable risk near 36 percent, and the odds rise steeply with dose so that heavy smokers such as this man are at several times higher risk. It accelerates atherosclerosis through endothelial dysfunction, reduced nitric oxide availability, oxidative modification of LDL, increased platelet aggregability and fibrinogen, and carbon monoxide mediated reduction of oxygen delivery, and it also promotes plaque instability and coronary vasospasm. In risk models such as SCORE2 and the pooled cohort equations, smoking produces a larger increment in absolute risk than any single non-modifiable characteristic present in this man, and he has no diabetes, hypertension, obesity, or family history to compete with it. Male sex and age do increase risk but are non-modifiable and, in a 55-year-old, contribute far less than heavy smoking. A body mass index of 26 kg/m² is only marginally above normal and is a weak independent predictor once other factors are accounted for. The clinical importance of identifying smoking is that it is reversible: coronary risk falls substantially within one year of cessation and approaches that of a never smoker within roughly 10 to 15 years. Every acute coronary syndrome admission should therefore include structured cessation counselling and pharmacotherapy alongside antiplatelet, statin, and other secondary prevention measures.
Why each option
- A.
- Correct. Heavy smoking is the dominant and modifiable driver of accelerated atherosclerosis and plaque rupture in this patient.
- B.
- Male sex raises baseline risk but is non-modifiable and contributes less than heavy smoking to an individual event.
- C.
- Age is a strong population level predictor, but at 55 years it adds less risk than smoking 30 cigarettes daily.
- D.
- A body mass index of 26 kg/m² is only mildly elevated and is a weak independent contributor to coronary risk.
Reference: 2019 ACC/AHA Guideline on the Primary Prevention of Cardiovascular Disease; INTERHEART study, Lancet 2004
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