Acute Myocardial Infarction-Clinical features | Medical Science Optional Notes for UPSC PDF Download

Precipitating factors

Vigorous physical exercise, emotional stress, or a medical or surgical illness.

Cardinal Symptoms

• Severe chest pain described as heavy, squeezing, and crushing, occurs at rest, is more intense, and has a longer duration compared to stable angina. The pain typically affects the central chest and/or epigastrium and may radiate to the arms, abdomen, back, lower jaw, or neck.
• Additional symptoms accompanying this type of chest pain include weakness, sweating, nausea, vomiting, anxiety, and a feeling of impending doom.
• The likelihood of painless ST-elevation myocardial infarctions (STEMIs) is higher in individuals with diabetes mellitus and increases with age.
• In elderly patients, a STEMI may manifest as sudden-onset breathlessness, which can progress to pulmonary edema.
• Uncommon presentations of STEMI include sudden loss of consciousness, a confusional state, a profound sensation of weakness, the onset of arrhythmias, signs of peripheral embolism, and an unexplained drop in arterial pressure.

General appearance

• Many patients experience anxiety and restlessness, trying unsuccessfully to alleviate pain by moving around in bed, changing their position, and stretching.
• Pallor, combined with sweating and coolness in the extremities, is a frequently observed phenomenon.

Signs

• In the initial hour of ST-elevation myocardial infarction (STEMI), approximately one-fourth of patients experiencing an anterior infarction display signs of heightened activity in the sympathetic nervous system, such as tachycardia and/or hypertension. Conversely, up to one-half of those with an inferior infarction exhibit indications of increased parasympathetic activity, including bradycardia and/or hypotension.
• Physical indicators of ventricular dysfunction encompass the presence of fourth and third heart sounds, a diminished intensity of the first heart sound, and a paradoxical splitting of the second heart sound.
• A temporary midsystolic or late systolic murmur at the apex may be present due to dysfunction of the mitral valve apparatus.
• If patients with transmural STEMI are examined frequently, a pericardial friction rub may be audible at some point during the course of the illness.
• A reduction in the volume of the carotid pulse is common, reflecting a decrease in stroke volume.
• During the initial week following STEMI, temperature elevations of up to 38°C may be observed.
• Arterial pressure tends to be variable.
• Lung crepitations and an elevated jugular venous pressure (JVP) are additional clinical manifestations.

Management of Unstable angina/NSTEMI

Reperfusion therapy is not utilized in the treatment of Unstable Angina.

• Hospital admission is recommended.
• Patients should observe bed rest.
• Continuous monitoring is necessary in specialized cardiac units.
• Oxygen support should be provided.

Anti-ischemic treatment

• Nitrates:
  • Usage: Helps alleviate ischemic pain but should be avoided in hypotension, severe RV infarction, or when the patient is on PDE-5 inhibitors.
  • Administration: Given sublingually or via IV infusion.
  • Dosage: NTG 0.4 mg every 15 minutes, with a maximum of 3 tablets to manage ischemic pain.
  • Infusion: Typically administered at 5-10 micrograms per minute.
  • Side Effects: Commonly causes headaches and can lead to hypotension.
• Beta Blockers:
  • Usage: Not recommended for inferior wall Ml due to potential bradycardia and hypotension. Also contraindicated in asthma and COPD (non-selective).
  • Type: Cardioselective options like metoprolol, usually dosed at 25-50 mg every 6 hours.
• Calcium Channel Blockers (Nifedipine):
  • Usage: Effective for ischemia but should be avoided in cases of pulmonary edema or left ventricular dysfunction.
• Morphine Sulphate:
  • Usage: Helpful for pain relief but should not be used in cases of hypotension.
  • Dosage: Typically administered as 5 mg IV initially, followed by 2 mg IV every 10 minutes as needed.

Anti-thrombotic therapy

• Oral Antiplatelet Therapy:
  • Aspirin: Initially administered at 325 mg, followed by a maintenance dose of 75-100 mg per day.
  • Clopidogrel: Initial dose ranges from 300-600 mg, then continued at 75 mg per day.
• Parenteral Antiplatelet Therapy:
  • Options: Includes Abciximab, Eptifibatide, Tirofiban, and Cangrelor.
• Anticoagulant Therapy:
  • Unfractionated Heparin (UFH): Initial bolus of 70-100 units/kg followed by an infusion at a rate of 12-15 units/kg per hour.
  • Enoxaparin SC: Administered subcutaneously.
  • Fondaparinux SC: Given at a dosage of 2.5 mg subcutaneously.
  • Bivalirudin: An alternative anticoagulant option.

Initial Treatment

• Begin with dual antiplatelet therapy using Aspirin and Clopidogrel, alongside anticoagulation (Enoxaparin, fondaparinux, or Bivalirudin) upon first contact.
• If the patient remains under medical treatment during hospitalization, maintain the dual antiplatelet and anticoagulant regimen.

Invasive Approach

• Patients with high-risk factors, ST segment deviations, or positive biomarkers undergo an invasive strategy involving cardiac catheterization followed by PCI or CABG, determined by coronary anatomy.

Long-Term Management

• Indefinitely continue Aspirin at a dosage of 75-100mg/day.
• Maintain Clopidogrel at 75mg/day for the subsequent 12 months.

Management of STEMI

Initial Management

• Evaluate vital signs and ensure stable hemodynamics.
• Establish intravenous access for medication administration.
• Admit the patient to the Cardiac ICU for continuous cardiac monitoring.
• Monitor oxygen saturation levels (SpO2) and maintain adequate oxygenation.
• Use Morphine (5mg IV initially, followed by 2mg IV every 10 minutes) to alleviate anxiety, noting its contraindication in cases of inferior wall Ml (Alternatives: injection pethidine or injection phenergan).
• Initiate immediate Dual Antiplatelet Therapy (DAPT):
  • Aspirin at 325 mg initially, followed by a maintenance dose of 75-100mg/day indefinitely.
  • Clopidogrel initially administered at 300-600mg, then continued at 75mg/day for the next 12 months.
• Administer sublingual nitrates (NTG 0.4 mg every 15 minutes, up to a maximum of 3 tablets) to manage ischemic pain associated with ST segment elevation, aiming to limit the size of the infarct through reperfusion therapy.

Reperfusion Therapy - Immediate Initiation

PCI-Capable Hospital

• Immediate transfer to the Cath lab for primary PCI, involving stent insertion.
• Crucial to achieve a first medical contact to device time within 90 minutes.
• Conduct a diagnostic angiogram as part of the procedure.
• Consider medical therapy for Prinzmetal angina; perform PCI if coronary anatomy permits or opt for CABG if not supportive.

PCI-Incapable Hospital

• Aim for Door in Door out time within 30 minutes and First Medical Contact to Device time within 120 minutes.
• If the anticipated First Medical Contact to Device time exceeds 120 minutes:
  • Initiate fibrinolytic therapy within 30 minutes.
  • Replace Streptokinase with tPA in the presence of allergic reactions.
  • tPA dosage: 15 mg bolus, then 50 mg IV over 30 minutes, followed by 35 mg over the next 60 minutes.
• In case of failed thrombolysis, consider RESCUE PCI. For recurrence, URGENT PCI may be necessary.
• Successful thrombolysis might lead to consideration of ELECTIVE PCI or CABG after recovery.

Complication Management

• Severe hypotension resulting from heart failure: Use vasopressors to address this issue.
• Pulmonary edema: Administer diuretics to manage the condition effectively.
• Arrhythmias, particularly ventricular fibrillation (VF): Treat with antiarrhythmic medications, defibrillation, or cardiac pacing, depending on the situation.

Long term management

•  Injected Heparin (UFH) used as a preventive measure against thromboembolism. 
• Beta-blockers (Metoprolol 50 mg taken orally twice a day) employed to alleviate anxiety and reduce cardiac workload. 
• ACE inhibitors prescribed to prevent cardiac remodeling and potential complications. 
• Statins utilized to manage hyperlipidemia. 
• Supportive therapies include:
  • Providing reassurance to the patient.
  • Encouraging complete bed rest.
  • Engaging in deep breathing exercises.
  • Promoting walking as an activity.
  • Advising against straining, and if necessary, suggesting the use of laxatives to alleviate constipation.

Prinzmetal's variant angina (PVA)

• Description: It's a syndrome marked by intense ischemic pain, often occurring at rest and linked with temporary ST-segment elevation.
• Cause: Stemming from localized spasms in a coronary artery, resulting in severe ischemia and potential complications like acute Ml, ventricular tachycardia, fibrillation, or sudden cardiac death.
• Patient Profile: Typically affects younger individuals with fewer coronary risk factors compared to other types of ACS. Smoking is a notable exception.
• Diagnosis: Coronary angiography reveals transient coronary spasms as the defining characteristic of this condition.
• Treatment: Mainly involves the use of nitrates and calcium channel blockers as primary therapeutic measures.
• Aspirin Consideration: Interestingly, aspirin might escalate the severity of ischemic episodes, potentially due to the coronary tone's sensitivity to slight changes in prostacyclin synthesis.

IHD-Repeats

Q1: Describe the clinical features, investigations and management of Acute Myocardial Infarction (1999)

Q2: Describe the symptoms and sign of acute Ml. How will you investigate the case arid what positive finding will you get in reports? Describe the treatmentin brief. (2007) 

Q3: What is unstable angina? How will you manage a patient with unstable angina? (2012) 

Q4: Enumerate various coronary risk factors. Describe the management of acute myocardial infarction in the emergency room. (2011) 

Q5: Discuss the pharmacological strategies available for the post-myocardial infarction management. (2013) 

Q6: A 60-year-old chronic smoker, obese gentleman who had been suffering from diabetes for last five years, not on regular treatment, developed ’Ghabarahat' and sudden breathlessness and perspiration.
(i) How would you work up this case? Draw a flow chart.
(ii) Enumerate the line of treatment in case ECG indicates acute inferior wall myocardial infarction.
(iii) Which lifestyle measures would you suggest to this person? (2014)