Which one of the following statements about influence of smoking on risk of coronary hea disease (CHD) is not true?
**Core Concept**
Smoking increases the risk of coronary heart disease (CHD) through various mechanisms, including endothelial dysfunction, inflammation, and atherosclerosis. The pathophysiology involves the release of free radicals, which damage the endothelium, leading to impaired vasodilation and increased platelet aggregation.
**Why the Correct Answer is Right**
Smoking accelerates atherosclerosis by increasing the levels of low-density lipoprotein (LDL) cholesterol and decreasing high-density lipoprotein (HDL) cholesterol. The chemicals in tobacco smoke also stimulate the release of catecholamines, leading to increased blood pressure and cardiac workload. Furthermore, smoking damages the endothelium, impairing its ability to produce nitric oxide (NO), a potent vasodilator. This results in decreased blood flow to the coronary arteries, increasing the risk of CHD.
**Why Each Wrong Option is Incorrect**
* **Option A:** Incorrect because smoking does increase the risk of CHD. The relationship between smoking and CHD is well-established, with smoking being a major risk factor for the development of atherosclerosis.
* **Option B:** Incorrect because smoking does accelerate atherosclerosis. The chemicals in tobacco smoke damage the endothelium, leading to increased inflammation and atherosclerotic plaque formation.
* **Option C:** Incorrect because smoking does increase the risk of CHD in women. Women who smoke are at increased risk of developing CHD, particularly after menopause.
**Clinical Pearl / High-Yield Fact**
Smoking is a major modifiable risk factor for CHD, and quitting smoking can significantly reduce the risk of developing CHD. The benefits of quitting smoking are evident within a few years, with the risk of CHD decreasing by 50% within 5 years of quitting.
**Correct Answer: A. Smoking does not increase the risk of CHD.**