A 52-year-old man with no significant past medical history is admitted to the Emergency Department with chest pain. His admission ECG shows anterior T wave inversion. On examination his blood pressure is 120/82 mmHg, pulse 90 / min and oxygen saturations are 97% on room air. He is now pain free. You calculate his 6 month mortality using GRACE to be 1.0%.
What initial therapy should be given?
Correct Answer D: The NICE guidelines would advocate the use of fondaparinux in this scenario. Given the clinical details in this case it is unlikely that angiography will be performed in the next 24 hours and hence unfractionated heparin is not required.
Acute coronary syndrome: management:
NICE produced guidelines in 2010 on the management of unstable angina and non-ST elevation myocardial infarction (NSTEMI). They advocate managing patients based on the early risk assessment using a recognized scoring system such as GRACE (Global Registry of Acute Cardiac Events) to calculate a predicted 6 month mortality.
All patients should receive:
Whilst it is common that non-hypoxic patients receive oxygen therapy there is little evidence to support this approach. The 2008 British Thoracic Society oxygen therapy guidelines advise not giving oxygen unless the patient is hypoxic.
Antithrombin treatment. Fondaparinux should be offered to patients who are not at a high risk of bleeding and who are not having angiography within the next 24 hours. If angiography is likely within 24 hours or a patients creatinine is > 265 μmol/l unfractionated heparin should be given.
Clopidogrel 300mg should be given to patients with a predicted 6 month mortality of more than 1.5% or patients who may undergo percutaneous coronary intervention within 24 hours of admission to hospital. Clopidogrel should be continued for 12 months.
Intravenous glycoprotein IIb/IIIa receptor antagonists (eptifibatide or tirofiban) should be given to patients who have an intermediate or higher risk of adverse cardiovascular events (predicted 6- month mortality above 3.0%), and who are scheduled to undergo angiography within 96 hours of hospital admission.
Coronary angiography should be considered within 96 hours of first admission to hospital to patients who have a predicted 6-month mortality above 3.0%. It should also be performed as soon as possible in patients who are clinically unstable.
The table below summaries the mechanism of action of drugs commonly used in the management of acute coronary syndrome:
In patients with atrial fibrillation (AF), which one of the following factors would make a rate control strategy, rather than rhythm control, more suitable?
Correct Answer D:
Atrial fibrillation: rate control and maintenance of sinus rhythm
The Royal College of Physicians and NICE published guidelines on the management of atrial fibrillation (AF) in 2006. The following is also based on the joint American Heart Association (AHA), American College of Cardiology (ACC) and European Society of Cardiology (ESC) 2012 guidelines
Agents used to control rate in patients with atrial fibrillation:
Agents used to maintain sinus rhythm in patients with a history of atrial fibrillation:
The table below indicates some of the factors which may be considered when considering either a rate control or rhythm control strategy
A 23-year-old woman is investigated after collapsing whilst jogging. She felt briefly unwell and dizzy prior to collapsing but quickly recovered. There has been no previous similar episodes. Routine blood tests are normal but the ECG shows a corrected QT interval of 480ms.
What is the most appropriate management?
Correct Answer B: An implantable cardioverter defibrillator is only required in high risk cases, for example if the patient has a QTc > 500ms or previous episodes of cardiac arrest.
Long QT syndrome:
Long QT syndrome (LQTS) is an inherited condition associated with delayed repolarization of the ventricles. It is important to recognize as it may lead to ventricular tachycardia and can therefore cause collapse/sudden death.
The most common variants of LQTS (LQT1 & LQT2) are caused by defects in the alpha subunit of the slow delayed rectifier potassium channel. A normal corrected QT interval is less than 430 ms in males and 450 ms in females.
Causes of a prolonged QT interval:
Features:
Management:
*the usual mechanism by which drugs prolong the QT interval is blockage of potassium channels. See the link for more details
**a non-sedating antihistamine and classic cause of prolonged QT in a patient, especially if also taking P450 enzyme inhibitor, e.g. Patient with a cold takes terfenadine and erythromycin at the same time
***note sotalol may exacerbate long QT syndrome
Which of the following is least associated with mitral valve prolapse?
Correct Answer E: Whilst some patients with acromegaly have mitral valve prolapse (MVP) it is not a common association. It should be remembered that the prevalence of MVP in a standard population is around 5-10%
Mitral valve prolapse:
Mitral valve prolapse is common, occurring in around 5-10 % of the population. It is usually idiopathic but may be associated with a wide variety of cardiovascular disease and other conditions
Associations:
A 54-year-old man with angina has a percutaneous coronary intervention with insertion of a drug eluting stent.
What is the single most important risk factor for stent thrombosis?
Correct Answer B: PCI: stent thrombosis -> withdrawal of antiplatelets biggest risk factor.
Diabetes mellitus is a risk factor for restenosis rather than stent thrombosis.
Percutaneous coronary intervention: Percutaneous coronary intervention (PCI) is a technique used to restore myocardial perfusion in patients with ischaemic heart disease, both in patients with stable angina and acute coronary syndromes. Stents are implanted in around 95% of patients - it is now rare for just balloon angioplasty to be performed.
Following stent insertion migration and proliferation of smooth muscle cells and fibroblasts occur to the treated segment. The stent struts eventually become covered by endothelium. Until this happens there is an increased risk of platelet aggregation leading to thrombosis.
Two main complications may occur:
Risk factors:
Types of stent:
Whilst this reduces restenosis rates the stent thrombosis rates are increased as the process of stent endothelialization is slowed.
Following insertion the most important factor in preventing stent thrombosis is antiplatelet therapy. Aspirin should be continued indefinitely. The length of clopidogrel treatment depends on the type of stent, reason for insertion and consultant preference.
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