Effects of smoking on coronary microcirculatory function: a twin study

Area of Science:

• Cardiology
• Vascular Biology
• Twin Studies

Background:

• Coronary microcirculatory dysfunction, assessed by coronary flow reserve (CFR), is an early indicator of cardiovascular risk in asymptomatic smokers.
• Inflammation and oxidative stress are hypothesized mechanisms linking smoking to microvascular damage.

Purpose of the Study:

• To investigate the relationship between smoking and coronary flow reserve (CFR).
• To explore potential shared genetic influences on smoking-related cardiovascular risk using twin data.

Main Methods:

• Studied 360 middle-aged male twins (smokers and non-smokers), including discordant smoking pairs.
• Measured coronary flow reserve (CFR) using positron emission tomography ([N(13)] ammonia) during adenosine stress.
• Assessed inflammation (IL-6, CRP) and oxidative stress (hydroperoxides, GSH/GSSG ratio).

Main Results:

• Smokers exhibited significantly lower CFR compared to non-smokers (2.25 vs. 2.75, p<0.01).
• This association remained after adjusting for cardiovascular risk factors and was only marginally affected by inflammation/oxidative stress biomarkers.
• In discordant twin pairs, smoking twins had lower CFR than their non-smoking co-twins (2.25 vs. 2.67, p=0.03).

Conclusions:

• Smoking has detrimental effects on the microvasculature in the early stages of cardiovascular disease.
• Mechanisms influencing smoking-related coronary microvascular dysfunction extend beyond peripherally measured inflammation and oxidative stress.