Treatment of Myocardial Infarction

Treatment of Myocardial InfarctionUNDER THE GUIDANCE OF : Dr. V.KRISHNA RAO PROF & HOD OF EMERGENCY MEDICINE

CHAIRPERSON : Dr. B.R. SHIVAKUMAR PROF & HOD OF DEPT OF MEDICINE

By,Dr. Mohammed YaqubIntern (2011 batch)Intern

Prehospital chest pain evaluation and treatment

Prehospital EMS providers 75 to 325 mg of aspirin (chewed) nonenteric-coated formulations.(goal is to quickly block thromboxane A2 formation in platelets)Previously on NTG : take 1 tab S/L ; Not improving after 5 min Seek medical help

Fibrinolysis preferredEarly presentation (3hr from symptom onset and delay to invasive strategy)Invasive strategy is not an option Catheterization laboratory occupied or not available Vascular access difficulties Lack of access to a skilled PCI laboratory Delay to invasive strategy Prolonged transport (Door-to-balloon)(door-to-needle) more than 1hr Medical contact-to-balloon or door-to-balloon more than 90 min

Invasive strategy preferredSkilled PCI laboratory is available with surgical backup Medical contact-to-balloon or door-to-balloon less than 90minHigh risk from STEMICardiogenic shockKillip class 3Contraindications to fibrinolysisLate presentation (> 3 hr)Diagnosis of STEMI is in doubt

Initial recognition and management in ER1. Airway, Breathing, Circulation (ABC)2. Vital signs, general observation3. Presence or absence of jugular venous distension4. Pulmonary auscultation for rales5. Cardiac auscultation for murmurs and gallops6. Presence or absence of stroke

Laboratory Investigations(should be performed, but should not delay the implementation of reperfusion therapy.)ECGSerum biomarkers for cardiac damageComplete blood count (CBC) with plateletsInternational normalized ratio (INR)Activated partial thromboplastintime (aPTT)Electrolytes and magnesiumBlood urea nitrogen (BUN),creatinineGlucoseComplete Lipid Profile

Control of cardiac painPain contribute to the heightened sympathetic activityTypically accomplished with combination of nitrates, analgesics, oxygen and -blockersOxygenArterial oxygen desaturation (SaO2< 90%) Uncomplicated STEMI during the first 6 hours

Control of cardiac painNitroglycerinPatients with ongoing ischemic discomforts/l 0.4 mg every 5 minutes for a total of 3 dosesIntravenous NTG : 0.6 to 1.2 mg/hourongoing ischemic discomfort that responds to nitrate therapy control of hypertensionNitrates should not be administered to patients with:systolic pressure < 90 mm Hg or to 30 mm Hg below baselinesevere bradycardia(< 50 bpm)tachycardia (> 100 bpm)suspected RV infarction.who have received a phosphodiesterase

Control of cardiac pain AnalgesiaMorphine sulfate (2 to 4 mg intravenously)NSAIDS Increase risk of cardiovascular events so should be discontinued [A sub study analysis from the ExTRACTTIMI-25trial showed increased risk of death, reinfarction, heart failure, or shock among patients on NSAID is within 7 days of enrollment].

Reperfusion therapyThe principal goal of fibrinolysis is prompt restoration of full IRA patencyStreptokinase , tPA(alteplase), TNK(tenecteplase), rPA(reteplase)TNK and rPA-bolus fibrinolyticsPromote conversion of plasminogen to plasmin, which subsequently lyses fibrin thrombi

Contraindications and cautions for fibrinolysis in STEMIAbsolute Contraindications:Any prior intracranial hemorrhageKnown structural cerebral vascular lesionKnown malignant intracranial neoplasmIschemic stroke within 3 months EXCEPT acute ischemic stroke within 3 hours Suspected aortic dissectionActive bleeding or bleeding diathesis (excluding menses)Significant closed-head or facial trauma within 3 months

Note: Age restriction for fibrinolysis has been removed compared with prior guidelines.

Relative Contraindications:Severe uncontrolled hypertension on presentation (SBP > 180 or DBP > 110)Prior ischemic stroke >3 monthsTraumatic or prolonged (> 10 mt.) CPR or major surgery (< 3 weeks)Recent (< 2 to 4 weeks) internal bleeding Noncompressible vascular punctures For streptokinase/anistreplase: prior exposure (> 5 days ago) or prior allergic reaction to these agentsPregnancy, Active peptic ulcer Current use of anticoagulants

Choice of fibrinolyticsWP- 4 hr. t-PA is the preferred treatment streptokinase t-PA equivalent choices -risk of death is low , and increased risk of ICH .WP-4 to 12 hr . streptokinase and t-PA are equivalent options, but streptokinase is probably preferable to t-PA because of cost considerations

Assesment of reperfusion after fibrinolysisNoninvasive findings, s/o reperfusion include:Relief of symptomsMaintenance and restoration of hemodynamic and/or electrical instabilityReduction of 50 % of the initial STE pattern on follow-up ECG 60 to 90 minutes after initiation of therapy

Anticoagulant therapyPrevention of DVT, pulmonary embolism, ventricular thrombus, cerebral embolization.Establishing & maintaining patency of IRA.Trials shown that more prolonged anticoagulant therapy is beneficial (duration of index hospita-lization) in patients receiving thrombolytic therapy

IV Unfractionated HeparinSelective Fibrinolytic Bolus of 60 U/kg (maximum 4000 U) followed by an infusion of 12 U/kg/hr (maximum 1000 U) Nonselective fibrinolytic agents-who are at high risk for systemic emboli (large or anterior MI, atrialfibrillation (AF), previous embolus, or known LV thrombus). LMWH-30mg iv followed by 1mg/kg every 12hr

Antiplatelets Aspirin should be given indefinitely to all STEMI pts. without a true aspirin allergy. Patients undergoing PCI are also given aspirin loadingPatients not on aspirin therapy should be given non enteric aspirin 325 mg before PCI. After PCI, use of aspirin should be continued indefinitely Clopidogrel 300mg loading dose given orally.

Thienopyridines Addition of P2Y12 inhibitor to aspirin warranted for most patients with STEMIIn patients for whom PCI is planned, clopidogrel should be started and continued.Patients receiving a stent (BMS or DES) clopidogrel 75 mg daily or prasugrel 10 mg for at least 12 months;If the risk of bleeding outweighs the anticipated benefit afforded by thienopyridine therapy, earlier discontinuation.Continuation of thienopyridines beyond 15 months may be considered in patients undergoing DES placement

Prior history of stroke and TIA for whom primary PCI is planned, prasugrel is not recommendedCABG planned ?... the drug should be withheld for at least 5 days in patients receiving clopidogrel and at least 7 days in patients receiving prasugrel.Probably indicated in patients receiving fibrinolytic therapy who are unable to take aspirin because of hypersensitivity or GI intolerance

Glycoprotien IIb/IIIa inhibitorsIt is reasonable to start abciximab as early as possible before primary PCI (with or without stenting) in patients with STEMI.Tirofibanor eptifibatide may be considered before primary PCI (with or without stenting) in patients with STEMI.

-blockersRelieve ischemic pain, reduce need for analgesics, reduce infarct size and life-threatening arrhythmiasContra indications: signs of heart failureevidence of a low output stateincreased risk for cardiogenic shockother relative contraindications (PR interval > 0.24 S. 2ndor 3rddegree AV block, or reactive airway disease)

Favorable effects with metoprolol , atenolol , carvedilol and timolol,Beta blockers with intrinsic sympathomimetic activity probably should not be chosen.Trial of esmolol in the presence of relative contraindications.

CCBsImmediate-release preparation of nifedipine increased risk of in-hospital mortalityVerapamil & diltiazem can be given for relief of ongoing ischemia or slowing of a rapid ventricular response in AF in patients with contraindication to beta blockers.INTERCEPT trial compared 300mg of diltiazem with placebo and Diltiazem did not reduce cardiac death, nonfatal reinfarction, during a 6-month follow-up

ACE InhibitorsImproves MI by reducing myocardial remodelling Recommended