workload of the heart. The pain of myocardial ischemia is likely to respond to any intervention that improves the relationship between oxygen demand and supply, like nitrates, beta blockers and oxygen. Nitrates Nitrates, like nitroglycerin, dilate blood vessels, which is beneficial against myocardial ischemia in two ways: By increasing blood flow in the coronary arteries and the amount of oxygen that arrives to heart muscle; and by relaxing all blood vessels in the body, thereby reducing the workload that heart needs to produce against them and the oxygen it consumes. The preferred mode of administration is sublingually. By relaxing blood vessels nitrates also reduce blood pressure, which must be carefully monitored; they must not be used if hypotension is present. They must also be avoided in patients who have taken sildenafil or other phosphodiesterase type 5 inhibitors (used for erectile dysfunction) within the previous 24–48 hours, as the combination of the two could cause a serious drop in blood pressure. Intravenous nitrates are useful in patients with hypertension or pulmonary edema. Beta blockers By reducing sympathetic stimulation of the heart, beta blockers decrease heart rate, blood pressure and cardiac output, and hence heart oxygen consumption. Beta-blockers alleviate ischemic pain, and have also been proved to reduce the size of infarcted heart muscle, the risk of arrhythmias, and the proportion of patients with acute coronary syndrome who actually evolve STEMI. However, they have also been shown to increase the risk of acute heart failure. Their early use is contraindicated if there are signs of congestive heart failure (e.g., Killip class II or above) or hypotension, along with other contraindications to beta blockers (slow heart rate, atrioventricular block); in the absence of contraindications beta blocker therapy should begin in the first 24 hours. It may be prudent to prefer oral rather than intravenous forms. Oxygen therapy Initial administration of oxygen to all patients with acute coronary syndrome is common practice; however, there is no evidence to support or refute that supplemental oxygen might be harmful or beneficial for cardiac patients who do not need it. It is currently recommended to give oxygen only to breathless patients or when blood oxygen saturation is low, e.g. <90%. Analgesics Analgesic agents that are most commonly used are opioids, and especially morphine, which is considered the analgesic of choice in patients with ST elevation. Along with its pain-controlling properties, morphine also reduces the work of breathing,