Impact of smoking on coronary microcirculatory resistance in patients with coronary artery disease

Abstract

The aim of this study was to investigate the relationship between coronary microvascular function and smoking using the 3 parameters fractional fow reserve (FFR), coronary fow reserve (CFRthermo), and index of microcirculatory resistance (IMR) in patients with coronary artery disease (CAD). A total of 97 CAD patients with 148 intermediate stenotic lesions were divided into two groups: current and former smokers (Smokers: n = 54), and those who had never smoked (Non-smokers: n = 43). Coronary physiology measurements were made following coronary angiography at rest and during hyperemia induced with intravenous adenosine triphosphate. If a patient had several intermediate lesions, the lesion producing the largest IMR value and minimum FFRmyo and CFRthermo value was selected. Averaged over all patients, the FFRmyo, CFRthermo, and IMR values were 0.86 ± 0.10, 2.66 ± 1.50, and 20.8 ± 10.7, respectively. There was no signifcant correlation between FFRmyo and IMR. There were no signifcant differences between smokers and non-smokers in FFRmyo value (median: 0.85 [IQR: 0.74-0.90] versus 0.87 [IQR: 0.83-0.90], P = 0.15) and CFRthermo value (median: 1.90 [IQR: 1.56-3.16] versus 2.10 [IQR: 1.50-2.67] U, P = 0.95). The IMR value was signifcantly greater in smokers (median: 24.2 [IQR: 16.8-32.5] U versus 18.5 [IQR: 15.4-27.0] U, P = 0.04). In multivariate analysis, smoking was an independent predictor of increased IMR. Smoking appears to have a detrimental effect on coronary microvascular function as measured by IMR.