| Myocardial Infarction | ||||||||||
| Signs and Symptoms | ||||||||||
| Chest pain, usually across the anterior precordium; described of tightness or squeezing | ||||||||||
| Pain may radiate to the arm, jaw, neck, arms, or back. Usually affects the left side. | ||||||||||
| Dyspnea, which may either accompany chest pain or not | ||||||||||
| Nausea and/or abdominal pain (often present in infarcts of the inferior wall) | ||||||||||
| Anxiety, diaphoresis, lightheadedness, and/or syncope | ||||||||||
| Diagnosis | ||||||||||
| Elevated creatinine kinase (CK-MB) enzymes | ||||||||||
| Chest pain and altered ECG readings | ||||||||||
| ST elevated initially, followed by T wave inversion with ST depression | ||||||||||
| Pathological Q-waves may appear within a couple hours or 24+ hours | ||||||||||
| Non-Q wave infarct: ST depression and T wave inversion may occur without ST elevation | ||||||||||
| Acute Treatment | ||||||||||
| Therapy | Reason | |||||||||
| Aspirin chewable 160-325mg stat | decreases mortality 25% when used alone (40% when combined with other thrombolytic therapies) | |||||||||
| Analgesia: morphine 2-5mg iv q5h prn | relief of pain and anxiety associated with MI | |||||||||
| Oxygen (> 90% saturation with 2-4L nasal cannula) | general measure used in treatment of MI. Improves overall mortality | |||||||||
| Nitroglycerin 10mcg/min for 24-48 hours after first symptoms | used to reduce ischemic events associated with myocardial infarction | |||||||||
| Thrombolytics (streptokinase, alteplase) | decreases morbidity and mortality about 30% (time dependent) | |||||||||
| ACE inhibitors initiated within 24 hours | decreases morbidity and mortality; greater benefit shown in patients with heart failure (EF < 40%) anterior wall myocardial infarction | |||||||||
| Lopressor 5mg iv q15m x 3 doses, followed by oral medication 12 hours after last iv dose | decreases incidence of ventricular arrhythmias, reinfarction, ischemia, and mortality | |||||||||
| Heparin within first 24-48 hours (to aPTT 1.5-2.0 times control (50-70 seconds) | shown to have beneficial effect on morbidity and mortalitiy; give after steptokinase/urokinase and give with alteplase/retaplase | |||||||||
| Calcium channel blockers | may be considered in non-Q wave myocardial infarction who have preserved LV function and no edema; also can be used to treat ischemia, hypertension, and atrial fibrillation if beta-blockers are contraindicated | |||||||||
| Secondary Treatment | ||||||||||
| EC Aspirin 80-325 daily | decreases rate of reinfarction and mortality by about 25% | |||||||||
| ACE inhibitors (ramipril) | decreases morbidity and mortality in patients with left systolic failure; continue for 4-6 weeks post-MI and discontinue if no evidence of left systolic failure | |||||||||
| Beta-blockers | decreases reinfarction and mortality about 25% | |||||||||
| Warfarin (maintain INR 2-3) | consider in patients with the following: chronic/paroxysmial atrial fibrillation, left ventricular thrombus, unable to take aspirin, extensive wall motion abnormalities, large anterior wall MI, or severe LV systolic dysfunction | |||||||||
| Lipid lowering therapy | HMG-CoA reductase inhibitors reduce mortality. Gemfibrozil improves mortality in patients with HDL cholesterol; goal LDL < 100mg/dl | |||||||||
| Return to Main Index | ||||||||||