Use of Ranolazine for the Treatment of Coronary Microvascular Dysfunction

Coronary microvascular dysfunction (CMD) is defined as a mismatch of myocardial blood supply and oxygen consumption due to a dysfunction of the coronary microvessels. Up to 20-30% of patients with CMD have progressive worsening of symptoms with significant impairment of quality of life. Large-scale randomized studies of the pharmacologic treatment of CMD are lacking. Classic anti-ischemic drugs are the initial form of treatment, but efficacy is often limited. Ranolazine has a unique mechanism of action that does not affect blood pressure or heart rate. When added to existing anti-anginal agents, ranolazine improved at least one domain in eight of ten studies in which a questionnaire was used to assess patient health status. Five studies evaluated coronary arterial flow reserve (CFR), reporting that patients with low values had significant improvement in CFR and suggesting that those with more severe CMD respond more favorably to ranolazine. In two studies, exercise duration and time to myocardial ischemia were significantly increased after treatment with ranolazine. Data are lacking for ranolazine use as the sole agent for CMD treatment. Some questions remain to be answered regarding ranolazine use for CMD. Larger studies of longer duration are needed to verify the effectiveness of ranolazine in the treatment of CMD.