Conventional drug therapy of patients with acute myocardial infarction.

In medicine and in cardiology one must be aware that there is no "standard" management for any condition. However, some guidelines can be offered for the management of myocardial infarction in the early stages. The following can be considered an aggressive but stepwise approach to therapy of patients with suspected myocardial infarction using conventional drugs with or without thrombolytic therapy or coronary angioplasty. Any patient presenting with prolonged chest pain occurring at rest should have an electrocardiogram. If the ECG is abnormal, an evolving myocardial infarction can be suspected. In this setting, oxygen should be administered if the patient is dyspneic, cyanotic, or has rales in the chest, intravenous nitroglycerin should be given, and the patient's response should be assessed. Caution should be observed at this point if the patient is sweating or hypotensive. Administration of a vasodilator in a dehydrated patient may drop the blood pressure further. If pain is relieved and the ECG returns to normal, the working diagnosis is severe angina. However, acute myocardial infarction should not be dismissed. A strong case for the use of intravenous heparin can be made to prevent the redevelopment of intracoronary clot inasmuch as thrombosis probably occurs in most patients presenting with unstable and severe angina, as it most surely does in patients with an evolving acute myocardial infarction. If nitrates and oxygen relieve chest pain but the ECG remains abnormal, for example, ST segment elevation, the diagnosis of acute evolving myocardial infarction must be considered and intravenous nitrates should be continued. If the patient has no relief of pain from nitrates and oxygen and the ECG remains abnormal, morphine sulfate should be administered intravenously in sufficient dosage to relieve the chest pain but not produce hypotension or hypoventilation. Once the diagnosis of myocardial infarction has been made, some would begin administering intravenous lidocaine as prophylaxis against the ventricular arrhythmias commonly encountered in the earlier stages of myocardial infarction. It has not been my practice to use prophylactic lidocaine, but I believe it is prudent to have a low threshold for the use of this drug in patients with frequent PVCs, especially if they are multifocal. If the patient exhibits symptomatic bradycardia or heart block, a trial with intravenous atropine is warranted. Additionally, while all of this is going on, one should contemplate using beta-blockers if there is good indication, and thrombolytic therapy if there are no contraindications to its use.