Which class of cardiac drugs is primarily used to dilate coronary arteries and decrease myocardial oxygen demand?

Nitrates are primarily used to dilate coronary arteries, which effectively increases blood flow to the heart muscle and alleviates conditions such as angina pectoris. These medications function by relaxing the smooth muscle in the blood vessel walls, leading to vasodilation. This dilation not only improves oxygen delivery to the myocardium but also reduces myocardial oxygen demand by decreasing preload and afterload.

Through this mechanism, nitrates play a crucial role in the management of cardiac conditions where there is an imbalance between the oxygen supplied to the heart and the oxygen required by the heart muscle, especially in situations of ischemia or increased workload. This aspect makes nitrates particularly valuable in treating patients with coronary artery disease or angina.