ACE and endothelial dysfunction: Calcium antagonist, however, can be first-line therapy in patients with angina pectoris with microvascular spasm.[9] Angiotensin-converting enzyme inhibitor (ACEI) may help reverse vascular hypertrophy and improve vascular compliance via improve endothelial dysfunction and vasoreactivity.[5] New anti-ischemic drugs such as ranolazine or ivabradine have been proven effective in some patients with microvascular angina.[10–12] ESC guidelines recommend the use of secondary prevention with aspirin and statin therapy.