Question 176#

A 60-year-old man who is investigated for exertional chest pain is diagnosed as having angina pectoris.

Which one of the following drugs is most likely to improve his long-term prognosis?

A. Atenolol

Correct Answer B:

Strong evidence exists supporting the use of aspirin in stable angina. The benefit of ACE inhibitors and beta blockers are significant in patients who've had a myocardial infarction but modest in those with stable angina. 

Angina pectoris: drug management:

The management of stable angina comprises lifestyle changes, medication, percutaneous coronary intervention and surgery. NICE produced guidelines in 2011 covering the management of stable angina.

Medication:

• All patients should receive aspirin and a statin in the absence of any contraindication
• Ssublingual glyceryl trinitrate to abort angina attacks
• NICE recommend using either a beta-blocker or a calicum channel blocker first-line based on 'comorbidities, contraindications and the person's preference'
• If a calcium channel blocker is used as monotherapy a rate-limiting one such as verapamil or diltiazem should be used. If used in combination with a beta-blocker then use a long-acting dihydropyridine calcium-channel blocker (e.g. modified-release nifedipine). Remember that beta blockers should not be prescribed concurrently with verapamil (risk of complete heart block)
• Iif there is a poor response to initial treatment then medication should be increased to the maximum tolerated dose (e.g. for atenolol 100mg od)
• If a patient is still symptomatic after monotherapy with a beta-blocker add a calcium channel blocker and vice versa
• If a patient is on monotherapy and cannot tolerate the addition of a calcium channel blocker or a betablocker then consider one of the following drugs: a long-acting nitrate, ivabradine, nicorandil or ranolazine
• If a patient is taking both a beta-blocker and a calcium-channel blocker then only add a third drug whilst a patient is awaiting assessment for PCI or CABG

Nitrate tolerance:

• Many patients who take nitrates develop tolerance and experience reduced efficacy
• The BNF advises that patients who develop tolerance should take the second dose of isosorbide mononitrate after 8 hours, rather than after 12 hours. This allows blood-nitrate levels to fall for 4 hours and maintains effectiveness
• This effect is not seen in patients who take modified release isosorbide mononitrate

Ivabradine:

• A new class of anti-anginal drug which works by reducing the heart rate
• Acts on the If ('funny') ion current which is highly expressed in the sinoatrial node, reducing cardiac pacemaker activity
• Adverse effects: visual effects, particular luminous phenomena, are common. Bradycardia, due to the mechanism of action, may also be seen
• There is no evidence currently of superiority over existing treatments of stable angina

Question 177#

Which one of the following is least associated with Tetralogy of Fallot?

A. Right ventricular outflow tract obstruction

Correct Answer D:
Right-to-left shunting is characteristic of Fallot's. It is however known that a small number of asymptomatic infants may initially have a degree of left-to-right shunting through the ventricular septal defect.

Tetralogy of Fallot:

Tetralogy of Fallot (TOF) is the most common cause of cyanotic congenital heart disease*. It typically presents at around 1-2 months, although may not be picked up until the baby is 6 months old.

The four characteristic features are:

• Ventricular septal defect (VSD)
• Right ventricular hypertrophy
• Right ventricular outflow tract obstruction, pulmonary stenosis
• Overriding aorta 

The severity of the right ventricular outflow tract obstruction determines the degree of cyanosis and clinical severity.

Other features:

• Cyanosis
• Causes a right-to-left shunt
• Ejection systolic murmur due to pulmonary stenosis (the VSD doesn't usually cause a murmur)
• A right-sided aortic arch is seen in 25% of patients
• Chest x-ray shows a 'boot-shaped' heart, ECG shows right ventricular hypertrophy

Management:

• Surgical repair is often undertaken in two parts
• Cyanotic episodes may be helped by beta-blockers to reduce infundibular spasm

*However, at birth transposition of the great arteries is the more common lesion as patients with TOF generally present at around 1-2 months. 

Question 178#

Each one of the following is an indication for an implantable cardiac defibrillator, except:

A. Previous myocardial infarction with non-sustained VT on 24 hr monitoring

Correct Answer B:

Implantable cardiac defibrillators:

Indications:

• Long QT syndrome
• Hypertrophic obstructive cardiomyopathy
• Previous cardiac arrest due to VT/VF
• Previous myocardial infarction with non-sustained VT on 24 hr monitoring, inducible VT on electrophysiology testing and ejection fraction < 35%
• Brugada syndrome

Question 179#

Which one of the following statements regarding catecholaminergic polymorphic ventricular tachycardia (CPVT) is correct?

A. Resting ECG typically shows T wave inversion in leads V1-V3

Correct Answer E:

Catecholaminergic polymorphic ventricular tachycardia:

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a form of inherited cardiac disease associated with sudden cardiac death. It is inherited in an autosomal dominant fashion and has a prevalence of around 1:10,000.

Pathophysiology:

• The most common cause is a defect in the ryanodine receptor (RYR2) which is found in the myocardial sarcoplasmic reticulum

Features:

• Exercise or emotion induced polymorphic ventricular tachycardia resulting in syncope
• Sudden cardiac death
• Symptoms generally develop before the age of 20 years

Management:

• Beta-blockers
• Implantable cardioverter-defibrillator

Question 180#

Which one of the following is least associated with Wolff-Parkinson White syndrome?

A. Mitral valve prolapse

Correct Answer D:

Wolff-Parkinson:

White Wolff-Parkinson White (WPW) syndrome is caused by a congenital accessory conducting pathway between the atria and ventricles leading to a atrioventricular reentry tachycardia (AVRT). As the accessory pathway does not slow conduction AF can degenerate rapidly to VF.

Possible ECG features include :

• Short PR interval
• Wide QRS complexes with a slurred upstroke - 'delta wave'
• Left axis deviation if right-sided accessory pathway*
• Right axis deviation if left-sided accessory pathway*

Differentiating between type A and type B:

• Type A (left-sided pathway): dominant R wave in V1
• Type B (right-sided pathway): no dominant R wave in V1

Associations of WPW:

• HOCM
• Mitral valve prolapse
• Ebstein's anomaly
• Thyrotoxicosis
• Secundum ASD

Management:

• Definitive treatment: radiofrequency ablation of the accessory pathway
• Medical therapy: sotalol**, amiodarone, flecainide

*In the majority of cases, or in a question without qualification, Wolff-Parkinson-White syndrome is associated with left axis deviation.

**Sotalol should be avoided if there is coexistent atrial fibrillation as prolonging the refractory period at the AV node may increase the rate of transmission through the accessory pathway, increasing the ventricular rate and potentially deteriorating into ventricular fibrillation.