Therapeutic studies in patients with syndrome X or INOCA and those with confirmed CMD
| Drug class | Syndrome X/INOCA population | CMD population |
| First-line antianginal agents | ||
| Beta blocker | Randomised double-blind crossover studies—reduced angina, less ST depression episodes, improved markers of endothelial function 41 | Not tested in this population |
| Calcium channel blockers | Reduced angina, increased exercise time 42 | Only single dose of intravenous diltiazem tested did not improve CFR immediately43 |
| Nitrates | Reduced ischaemic threshold to exercise or rapid pacing 44 | Not tested in this population |
| Second-line antianginal agents | ||
| Nicorandil | Not tested | Increased ischaemic threshold (using CFR <3.0 as CMD inclusion) 45 |
| Ranolazine | Contradictory, improved or unchanged symptoms46 | Improved symptoms and reduced coronary microvascular resistance measured invasively (using CFR<2.5 or IMR>20 U as CMD inclusion) 47 |
| Disease-modifying agents | ||
| ACE inhibitors | Increased exercise duration, ischaemic threshold, endothelial function and CFR 48 | Improved CFR at 16 weeks (using CFR<3.0 as CMD inclusion) 49 |
| Statins | Improved symptoms, exercise tolerance and endothelial function 50 | Improved coronary ACh CFR after 6 months treatment (using ACh CFR <1.5 as CMD inclusion) 32 |
Green text emphasises improvement with medication and red text emphasises deterioration with medication.
CFR, coronary flow reserve; CMD, coronary microvascular dysfunction; INOCA, ischaemia with no obstructive coronary arteries.