Evaluation of coronary endothelial dysfunction in healthy young smokers: Cold pressor test using [ 15O]H 2O PET

Abstract

The purpose of this study was to investigate coronary endothelial dysfunction in young healthy smokers by measuring myocardial blood flow (MBF) using [ 15O]H 2O-PET. The study population was 18 young male volunteers consisted of 9 smokers (age: 23.8±1.1 yr) and 9 non-smokers (age: 25.0±2.5 yr). The smokers had been smoking cigarettes for 6.6±2.5 pack years. Myocardial [ 15O]H 2O-PET was performed at rest, during cold (5 °C) pressor stimulation and during adenosine infusion. Left ventricular (LV) input function and tissue time–activity curves were obtained by drawing region of interest (ROI) on the LV blood pool and myocardium images obtained by non-negative matrix factorization (NMF) of dynamic [ 15O]H 2O-PET data, and MBF was calculated using these time–activity curves and single compartmental model. There were no significant difference in resting MBF between two groups (smokers: 1.43±0.41 and non-smokers: 1.37±0.41 ml/g/min; P=NS). However, during cold pressor stimulation, MBF in smokers was significantly lower than that in non-smokers (1.25±0.33 vs. 1.59±0.29 ml/g/min; P=0.019). MBF changed to 90±24% of resting MBF in smokers and 122±28% in non-smokers. The difference in the ratio of cold pressor MBF to basal MBF between two groups was also significant ( P=0.024). During adenosine infusion, however, hyperemic MBF did not differ significantly between smokers and non-smokers (5.81±1.99 vs. 5.03±1.27 ml/g/min; P=NS). This study shows that [ 15O]H 2O PET analysis can reveal that endothelial dysfunction occurs in even young smokers of about 6 pack years.