Nitrate-Induced Headache May Have Confounding Factors

Additionally, since vasodilatory effects of nitrates may be blunted by the volume expansion and activated renin-angiotensinaldosterone system due to heart failure [5] , whether patients with heart failure or lower ejection fraction were excluded from the study or not should be stated in the study. Since carotid artery disease or peripheral artery disease is accompanied with endothelial dysfunction [6] and can influence NIH, the presence of overt or subclinical carotid atherosclerosis in patients with higher SYNTAX scores could have been discussed as a confounding factor for irresponsiveness to nitrate. At last NIH can be used as a clinical variable to predict the complexity or burden of coronary atherosclerosis in patients with stable angina pectoris. However, it should not be used as a test method in patients with acute coronary syndrome, because new onset angina could have been developed due to a thrombotic lesion on a fissured or ruptured non-critically stenotic coronary artery plaque located at a single coronary artery or only at one arterial segment. In conclusion, the relationship of NIH and features of coronary atherosclerosis has many confounding factors and may be influenced by many clinical and pathophysiological factors. Furthermore, the results are promising and may be used to provide a novel clinical tool if it is developed or integrated in a scoring system.