Ref : harrisons-manual-of-medicine-16th-edition pg no: 622-624 TREATMENT Initial Therapy Initial goals are to: (1) quickly identify if patient is candidate for reperfusion therapy, (2) relieve pain, and (3) prevent/treat arrhythmias and mechanical complications. * Aspirin should be administered immediately (162-325 mg chewed at presentation, then 162-325 mg PO qd), unless pt is aspirin-intolerant. * Perform targeted history, exam, and ECG to identify STEMI (
1 mmST elevation in two contiguous leads or new LBBB) and appropriateness of reperfusion therapy , which reduces infarct size, LV dysfunction, and moality. * Primary PCI is generally more effective than fibrinolysis and is preferred at experienced centers capable of performing procedure rapidly , especially when diagnosis is in doubt, cardiogenic shock is present, bleeding risk is increased, or if symptoms have been present for
3 h. * Proceed with IV fibrinolysis if PCI is not available or if logistics would delay PCI
1 h longer than fibrinolysis could be initiated (Fig. 123-1). Dooo- needle time should be  30 min for maximum benefit. Ensure absence of contraindications before administering fibrinolytic agent. Those treated within 1-3 h benefit most; can still be useful up to 12 h if chest pain is persistent or ST remains elevated in leads that have not developed new Q waves. Complications include bleeding, reperfusion arrhythmias, and, in case of streptokinase (SK), allergic reactions. Heparin should be initiated with fibrinolytic agents other than SK ; maintain aPTTT at 1.5-2.0 control (
50-70 s). * If chest pain or ST elevation persists
90 min after fibrinolysis, consider referral for rescue PCI. Later coronary angiography after fibrinolysis generally reserved for pts with recurrent angina or positive stress test. The initial management of NSTEMI (non-Q MI) is different . In paicular, fibrinolytic therapy should not be Additional Standard Treatment (Whether or not reperfusion therapy is undeaken): * Hospitalize in CCU with continuous ECG monitoring. * IV line for emergency arrhythmia treatment. * Pain control: (1) Morphine sulfate 2-4 mg IV q5-10min until pain is relieved or side effects develop ; (2) nitroglycerin 0.3 mg SL if systolic bp
100 mmHg; for refractory pain: IV nitroglycerin (begin at 10 g/min, titrate upward to maximum of 200 g/min, monitoring bp closely); do not administer nitrates within 24 h of sildenafil or within 48 h of tadalafil (used for erectile dysfunction); (3) -adrenergic antagonists * Oxygen 2-4 L/min by nasal cannula (maintain O2 saturation
90%). * Mild sedation (e.g., diazepam 5 mg PO qid). * Soft diet and stool softeners (e.g., docusate sodium 100-200 mg/d). * -Adrenergic blockers reduce myocardial O2 consumption, limit infarct size, and reduce moality. Especially useful in pts with hypeension, tachycardia, or persistent ischemic pain; contraindications include active CHF, systolic bp  95 mmHg, hea rate  50 beats/min, AV block,or history of bronchospasm. Administer IV (e.g., metoprolol 5 mg q5-10min to total dose of 15 mg), followed by PO regimen (e.g., metoprolol 25-100 mg bid). * Anticoagulation/antiplatelet agents: Pts who receive fibrinolytic therapy are begun on heparin and aspirin as indicated above. In absence of fibrinolytic therapy, administer aspirin, 160-325 mg qd, and low-dose heparin (5000 U SC q12h for DVT prevention). Full-dose IV heparin (PTT 2 control) or low-molecular-weight heparin (e.g., enoxaparin 1 mg/kg SC q12h) followed by oral anticoagulants is recommended for pts with severe CHF, presence of ventricular thrombus by echocardiogram, or large dyskinetic region in anterior MI. Oral anticoagulants are continued for 3 to 6 months, then replaced by aspirin. * ACE inhibitors reduce moality in pts following acute MI and should be prescribed within 24 h of hospitalization for pts with STEMI--e.g., captopril (6.25 mg PO test dose) advanced to 50 mg PO tid. ACE inhibitors should be continued indefinitely after discharge in pts with CHF or those with asymptomatic LV dysfunction ; if ACE inhibitor intolerant, use angiotensin receptor blocker (e.g., valsaan or candesaan). * Serum magnesium level should be measured and repleted if necessary to reduce risk of arrhythmias.