Why Do Nitrates Have Limited Efficacy in Coronary Microvessels?

Targeted Therapies for Microvascular Disease

“…Act on arteriolar endothelium to cause vasodilation. Whilst traditionally prescribed for angina, accumulating evidence seems to suggest negligible benefit and even potential harm with the use of long-acting nitrates on MVA 44,45 . Reduced responsiveness from coronary arteries, steal syndrome from redistribution of blood flow to areas of adequate perfusion, and poor medication tolerance and have all been suggested as potential reasons for the lack of nitrate benefit in MVA 44,45 .…”

Current views on angina pectoris in patients with intact coronary arteries (INOCA)

“…Також додатковим параметром є визначення мікроциркуляційного опору у вигляді IMR, який розраховується як добуток дистального коронарного тиску на максимальну гіперемію, помножену на середній час гіперемії [37]. Збільшення IMR (>25) вважається репрезентативним показником мікроваскулярної дисфункції [38].…”

How to Diagnose and Manage Angina Without Obstructive Coronary Artery Disease: Lessons from the British Heart Foundation CorMicA Trial

“…[42] Lack of efficacy may relate to poor tolerability, steal syndromes through regions of adequately perfused myocardium and/or related to the reduced responsiveness of nitrates within the coronary microcirculation. [43] There is significant clinical overlap between MVA and HFpEF,[44] so inferences about nitrate response may be drawn from the Nitrate’s Effect on Activity, Tolerance in HFpEF (NEAT-HFpEF) study. In this randomised controlled trial, HFpEF patients on isosorbide mononitrate actually did worse with reduced activity levels assessed using an accelerometer.…”