The Relationship Between Nitrate-Induced Headache and -Blood Viscosity: An Observational Prospective Study

Abstract

Nitrates are one of the most prescribed medications in the treatment of angina pectoris today. Headache is the most common side effect of nitrates, and there is limited prospective data on the determinants of this effect. Our aim in this study is to open a foresight window for clinicians in clinical practice by explaining the possible relationship between nitrate-induced headache and whole-blood viscosity (WBV). After coronary revascularization treatment, 869 patients with angina who were prescribed nitrate preparations were divided into groups according to the development of headache or not and categorized according to the 4-grade scale level. Those who had no headache during nitrate use were graded as grade 0, those who felt mild headache were grade 1, those who felt moderate headache were grade 2, and those who described severe headache were graded as grade 3. The groups were compared according to WBV values. A total of 869 participants were included in the study. Most patients (82.1%) experienced some level of headache. Headache severity correlated with both WBV at high shear rate (r = 0.657; P < 0.001) and WBV at low shear rate (r = 0.687; P < 0.001). In multivariate analysis, WBV was determined as an independent predictor of headache experience. WBV predicted nitrate-induced headache with 75% sensitivity and 75% specificity at high shear rate and 77% sensitivity and 77% specificity at low shear rate. WBV seems to be one of the major determinants for nitrate-induced headache. WBV may be a guide for initiating alternative antianginal drugs without prescribing nitrates to the patient to increase patient compliance.