034 Altered arterial stiffness and subendocardial viability ratio in young healthy smokers after acute exercise: Impairments in the vascular reserve

Abstract

Studies showed that long-standing smokers have stiffer arteries at rest. However, the effect of smoking on the ability of the vascular system to respond to increased demands (‘vascular reserve’) has not been investigated. The purpose of this study was to estimate the effect of acute and chronic smoking on arterial stiffness, subendocardial viability ratio, and the ‘vascular reserve’ in young healthy individuals. Healthy light smokers (n = 24) and non-smokers (n = 53) underwent pulse wave analysis and carotid-femoral pulse wave velocity (cfPWV) measurements at rest, and 2, 5, 10, and 15 minutes following an exercise test to exhaustion. Smokers were tested, 1) after 12h abstinence from smoking and 2) immediately after smoking one cigarette. At rest after abstinence, smokers had higher augmentation index compared with non-smokers (−3.5 ± 10.3 vs. −11.4 ± 10.1; P = 0.04), while subendocardial viability ratio was not significantly different. Acute smoking increased augmentation index (−1.0 ± 7.9 vs. −11.4 ± 10.1; P = 0.006) and decreased subendocardial viability ratio (130.2 ± 20.0 vs. 173.4 ± 44.8; P < 0.0001) compared with non-smokers, and decreased subendocardial viability ratio compared with 12h abstinence (130.2 ± 20.0 vs. 163.7 ± 26.8; P = 0.03). After exercise, subendocardial viability ratio area under the curve in non-smokers was lower than smokers after 12hr abstinence (−884.1 ± 297.1 vs. −662.1 ± 205.2; P = 0.07) and after acute smoking (−884.1 ± 297.1 vs. −339.3 ± 177.9; P < 0.0001) and augmentation index was higher than smokers after 12h abstinence (191.3 ± 100.4 vs. 75.7 ± 86.7; P = 0.01) and after acute smoking (191.3 ± 100.4 vs. 58.11 ± 81.7; P = 0.006). Impairment in the ‘vascular reserve’ was noted in young, healthy, light smokers before changes in arterial stiffness or subendocardial viability ratio occurred at rest. Even light smoking in young healthy individuals appears to have harmful effects on vascular function, affecting the ability of the vascular bed to respond to increased demands. Moreover, we propose that while increases in arterial stiffness and decreases in subendocardial viability ratio at rest may be detrimental, after exercise these changes may represent beneficial physiological responses to physical stress.