Cardiology

• There are 3 acute coronary syndromes: 

  • Unstable angina- A partial/intermittent blockage of the artery
  • Non-ST-elevation myocardial infarction- A partial/intermittent blockage of the artery resulting in myocardial necrosis
  • ST-elevation myocardial infarction- complete and persistent blockage of the artery resulting in myocardial necrosis with ST elevation shown on the ECG

  They are caused by a thrombus forming on an atheromatous plaque in a coronary artery.

  High sensitivity blood tests for serum troponin are used to differentiate between NSTEMI and unstable angina.
• Initial management of the acute coronary syndromes:

  • Offer aspirin 300mg STAT as soon as possible
  • Offer pain relief with glyceryl trinitrate (sublingual or buccal), and/or intravenous opioids
  • Monitor patient’s oxygen saturations and blood glucose levels (look out for hyperglycaemia)
• The secondary prevention of cardiac events includes cardiac rehabilitation (advice about lifestyle changes, stress management after the traumatic experience, and health education).

  For all patients with NSTEMI and STEMI, offer:

  • ACE inhibitor - continued indefinitely
  • Beta blocker - continued long-term
  • Dual antiplatelet therapy - aspirin continued indefinitely, second antiplatelet stopped after 12 months
  • Statin - continued lifelong e.g. atorvastatin 80mg
• If patient is intolerant to an ACEi e.g. dry cough, an ARB can be given instead. ACEi dose is titrated upwards at short intervals e.g. 12 to 24 hours. Measure renal function, serum electrolytes and blood pressure before starting ACEi or ARB and again within 1 or 2 weeks of starting treatment. Monitor as the dose is being titrated upwards. When maximum tolerated dose has been reached, monitor annually.

  The target blood pressure when on ACEi is 130/80. Ask patients to check their BP at least once a week.
• Beta blockers reduce the workload of the heart. Target heart rate for a patient on beta blockers = 60 bpm

  Started when haemodynamically stable

  Titrate up to maximum tolerated dose

  Duration depends on patient:

  • If patient has a reduced left ventricular ejection fraction (LVEF) – continued indefinitely
  • If patient has preserved ejection fraction - balance benefits and risks of discontinuation after 12 months
  • Continue long term
  • Side effects disappear after a few weeks e.g. coldness of the hands and feet, tiredness, dizziness, feeling faint
  • Contraindicated in second or third degree heart block
• Antiplatelets stop platelets from clumping onto the atheroschlerotic plaque. Patient may carry around an alert card. DAPT is aspirin plus either clopidogrel, prasugrel or ticagrelor.

  Clopidogrel has the lowest bleeding risk, therefore for people at risk of bleeding, use clopidogrel

  May recommend a PPI to protect the stomach from the antiplatelets but omeprazole interacts with clopidogrel so choose lansoprazole instead.
• The target LDL level for people who have had an acute coronary syndrome is 1.4 mmol/L. Patients continue statins lifelong. They can use a high intensity statin, the most common being atorvastatin 80mg. Statins are also known as HMG CoA inhibitors.

  Statins can cause muscle pain, myopathy and rhabdomyolysis.

  
• Aldosterone antagonists include spironolactone and eplerenone. These are given to people who have had an acute MI and who have symptoms and/or signs of heart failure and reduced LVEF. Monitor renal function and serum potassium before and during treatment. If hypokalaemia is a problem, halve the dose of the aldosterone antagonist or stop the drug.
• Glyceryl trinitrate dilates the blood vessels when the patient is experiencing chest pain, so blood can flow more easily.
• Non-dihydropyridine calcium channel blockers can be given as an alternative to beta blockers after acute coronary syndromes, e.g. verapamil and diltiazem.
• Atrial fibrillation results from irregular, disorganised electrical activity in the atria, leading to an irregular ventricular rhythm.

  The most common causes include ischaemic heart disease, hypertension, valvular heart disease and hyperthyroidism.

  Stroke and thromboembolism are the main complications of atrial fibrillation. Other complications include heart failure, cardiomyopathy, critical cardiac ischaemia and reduced quality of life.
• For patients with atrial fibrillation, the CHA2DS2VASc assessment tool assesses the risk of stroke, and the ORBIT assessment tool assesses the risk of major bleeding.

  Chadsvasc looks at age, sex, history of congestive heart failure, history of hypertension, history of stroke/TIA/thromboembolism, history of vascular disease and history of diabetes. Start anticoagulation if a male scores 2 or a female scores 3.

  ORBIT looks at: sex, age >74, history of bleeding, eGFR <60 and treatment with antiplatelet agents.
• All patients with life-threatening haemodynamic instability (inadequate blood flow) caused by new-onset atrial fibrillation should undergo emergency electrical cardioversion, without delaying, to achieve anticoagulation. In patients presenting acutely but without life-threatening haemodynamic instability, rate or rhythm control can be offered if the onset of arrhythmia is less than 48 hours. If AF has been present for more than 48 hours, electrical cardioversion is better but this should be delayed until the patient has been anticoagulated for at least 3 weeks due to left atrial thrombus risk.
• For urgent rate control, you can give a beta blocker intravenously or a rate-limiting calcium channel blocker e.g. verapamil or diltiazem (but CCB should not be used in heart failure with reduced ejection fraction).
• For pharmacological cardioversion, you can use flecainide acetate or amiodarone. If offering electrical cardioversion, you should give adequate rate control in the time where the patient is waiting for their cardioversion. Amiodarone started 4 weeks before and continued for up to 12 months after electrical cardioversion to maintain sinus rhythm may be considered.
• Rate control:

  • Makes sure the ventricular rate is tolerable, even though the atria are going really fast
  • Usually first line
  • Either a beta-blocker (e.g. atenolol, bisoprolol, carvedilol) or a rate limiting CCB (non-dihydropyridine) e.g. diltiazem or verapamil
  • Another option is digoxin (good for people who do little or no exercise, if other rate limiting drugs are not suitable)
  • If the rate control isn’t working, combine two of the following: beta blocker, digoxin or diltiazem. (interaction between beta blockers and diltiazem- can cause bradycardia, AV block, asystole or sudden death).
• Rhythm Control:

  • For people who still get symptoms after their rate has been controlled
  • These include: 
  • Electrical cardioversion (but if the patient has had an episode lasting longer than 48 hours, delay this until the patient has been anticoagulated for 3 weeks!)
  • This is because of the risk of a left atrial thrombus
  • Antiarrhythmic drugs e.g. flecainide, amiodarone, propafenone
• • Oral anticoagulation should be offered to patients with a confirmed diagnosis of AF in whom a stable sinus rhythm has not been successfully restored within 48 hours of onset.
  • This could be using a DOAC, and if this is contraindicated give warfarin. DOACs should not be given in CrCl < 15