A 20-year-old male presents to his GP with palpitations. He reports his heart skips a beat and then races for 30 seconds to a minute. On examination, he is tachycardic with a heart rate of 103 and his ECG was regular but revealed a short PR interval, wide QRS complexes with a slurred upstroke - 'delta wave'.

Which of the following is the most likely diagnosis?

Options:
explanation: Brugada syndrome is a genetic condition caused by sodium channelopathies. It is also a common cause of sudden cardiac death. The condition is usually diagnosed by characteristic ECG changes and at least one clinical criterion. Examples include ventricular fibrillation (VF) or polymorphic VT, a family history of sudden cardiac death under the age of 45, syncope, ECG signs in the family, inducible VT and nocturnal agonal breathing. Special provocation tests eg ajmaline, are also used for diagnosis.
name: Brugada syndrome
label: d
answer: no
explanation: Hypertrophic obstructive cardiomyopathy (HOCM) is an autosomal dominant disorder of muscle tissue caused by defects in the genes of the proteins that code for the sarcomere such as myosin, troponin and alpha-tropomyosin. It is often asymptomatic and thereby comprises the most common cause of sudden cardiac death in the young. Symptoms may include exertional dyspnoea, chest pain or syncope after exercise. ECG changes include typical left ventricular hypertrophy tall QRS complexes, non-specific ST segment and T-wave abnormalities, progressive T-wave inversion and deep Q waves.
name: Hypertrophic obstructive cardiomyopathy
label: b
answer: no
explanation: Polymorphic VT is a broad-complex tachycardia originating from a ventricular ectopic focus. It has the potential to precipitate ventricular fibrillation and hence requires urgent treatment. It is a diagnosis which is split into subtypes. The most common subtype of polymorphic VT is torsades de pointes which is precipitated by prolongation of the QT interval - not present in this case. The electrocardiogram characteristically shows QRS complexes 'twisting' around the isoelectric line.
name: Polymorphic ventricular tachycardia (VT)
label: c
answer: no
explanation: Wolff-Parkinson-White (WPW) syndrome is caused by a congenital accessory conducting pathway between the atria and ventricles leading to an atrioventricular re-entry tachycardia (AVRT). Typical ECG features include a short PR interval, wide QRS complexes with a slurred upstroke - 'delta wave' as well as left axis deviation if right-sided accessory pathways exist and right axis deviation if left-sided accessory pathways are present.
name: Wolff-Parkinson-White syndrome
label: a
answer: yes
explanation: A pulmonary embolism (PE) is when a blood clot in the pulmonary arterial vasculature develops, usually from an underlying deep vein thrombosis (DVT) of the lower limbs. Sudden-onset shortness of breath, pleuritic chest pain, and haemoptysis are the 'typical' triad, although note that all three features are rarely present. ECG findings include normal or sinus tachycardia most commonly. In a massive PE, there may be evidence of right-heart strain (with P pulmonale, right axis deviation, right bundle branch block, and non-specific ST/T wave changes). The classic S1Q3T3 (deep S waves in lead I, pathological Q waves in lead III, and inverted T waves in lead III) is relatively uncommon (<20% of patients).
name: Pulmonary embolism
label: e
answer: no

Correct answer: a