Impaired nitrate-mediated dilatation could reflect nitrate tolerance in patients with coronary artery disease

Aim To investigate whether nitrate-mediated dilatation (NMD) of the brachial artery could be impaired by the use of nitrates and reflect nitrate tolerance in coronary artery disease (CAD) patients. Methods A total of 243 patients (mean age 61 ± 12 years, 146 male) were recruited before coronary angiography. Gensini score was calculated to assess the severity of CAD. Flow-mediated dilatation (FMD) and NMD of the brachial artery were measured. Results NMD progressively decreased from subjects without CAD (control group, n = 71) to non-nitrate users (n = 64) and nitrate users (n = 108) with CAD (16.2 ± 6.01% versus 13.4 ± 5.57% versus 9.57 ± 4.52%, P < 0.001 for all). Multiple linear regression analysis showed that age, FMD, diameter of the brachial artery, hypertension, and nitrate use were independent determinants of NMD. In subgroup analysis of patients with high Gensini score (> 10), nitrate users (n = 56, 9.00 ± 4.00%) had a significant lower NMD than non-users (n = 28, 12.4 ± 5.45%, P < 0.001), but no difference in other parameters including age, prevalence of hypertension, FMD, Gensini score and use of other medications. Conclusions The use of nitrates independently impaired NMD in CAD patients. An impaired NMD could be a comprehensive index of nitrate tolerance in patients with CAD.