To measuring the CFR and IMR in 40 SCAD patients with ongoing chest pain who are at least 3 months from their dissection to determine the proportion with microvascular dysfunction and to investigate prospectively whether the addition of an ACEI or a statin to usual care in patients with ongoing chest pain and a CFR <3.0 improves chest pain frequency by Seattle Angina Questionnaire (SAQ) at 16 weeks compared to placebo.