Efficacy of Diltiazem to Improve Coronary Microvascular Dysfunction: a Randomized Clinical Trial

"Diltiazem hydrochloride is a calcium ion influx inhibitor (slow channel blocker or calcium antagonist). It is a white to off-white crystalline powder with a bitter taste. It is freely soluble in water, methanol and chloroform. It has a molecular weight of 450.98.~It provides its therapeutic effects by blocking the influx of calcium ions into vascular smooth and cardiac muscle cells during membrane depolarization. The decrease in intracellular calcium causes relaxation of smooth muscle cells and cardiac myocytes by inhibiting actin-myosin interactions. Vasodilation subsequently results in decreased peripheral vascular resistance. The antihypertensive effect of diltiazem in hypertensives is greater than in normotensives.~Diltiazem is registered for the treatment of hypertension, heart rate control in supraventricular tachycardia, chronic stable angina pectoris and angina pectoris resulting from coronary artery spasm."

Matching placebo capsules, given QD per oral use. Placebo capsules will be used in the same manner with the same dose titration.