Club doctor said my heart tracing looked odd

The case

19-year-old man. Club doctor said my heart tracing looked odd

He is a semi-professional footballer seen for routine pre-participation screening. He reports no symptoms, takes no regular medication and has no family history of sudden cardiac death.

On arrival

Heart rate: 78
Blood pressure: 122/74

Stage 1 of 3

A resting 12-lead ECG is recorded as part of the screening, and his examination is normal.

Tracing 1 of 2 for the quiz “Club doctor said my heart tracing looked odd”. — 12-lead, 25 mm/s, 10 mm/mV Open this tracing in the studio

What is the most likely diagnosis?

AWolff-Parkinson-White pattern Correct answer Your answer
BLeft bundle branch block Your answer
COld anteroseptal infarction Your answer
DLeft ventricular hypertrophy with strain Your answer

The PR interval is short at 80 ms, the QRS starts with a slurred delta wave that is clearest in II, aVF and V5-V6, and the complex is broad at 135 ms, which together make this ventricular pre-excitation. Left bundle branch block would have a normal PR interval and no slurred initial upstroke, and the deep S waves in V1-V2 are a pseudo-infarct pattern rather than the Q waves of an old infarct. A predominantly negative V1 commonly points to a right-sided pathway, although localisation algorithms are imprecise.

What would you do next?

ARefer to cardiology for risk stratification Correct answer Your answer
BReassure him and clear him to play Your answer
CStart bisoprolol Your answer
DRepeat the ECG in 12 months Your answer

In a competitive athlete with asymptomatic pre-excitation, the risk should be stratified before he is cleared to play, and the 2019 ESC guidelines support an EP study for this. The danger lies not in the pattern itself but in rapid antegrade conduction over the pathway if he ever develops AF.

Stage 2 of 3

Three weeks later, while still awaiting his clinic appointment, he develops a racing heart of sudden onset during training, which has lasted 40 minutes by the time he is seen. He is alert but mildly lightheaded.

Tracing 2 of 2 for the quiz “Club doctor said my heart tracing looked odd”. — 12-lead, 25 mm/s, 10 mm/mV Open this tracing in the studio

Observations

SpO2: 98%
Heart rate: 196
Blood pressure: 112/70

What is the most likely mechanism?

AOrthodromic AVRT Correct answer Your answer
BTypical AVNRT Your answer
CAtrial flutter with 2:1 block Your answer
DSinus tachycardia Your answer

The rhythm is regular and narrow, with a QRS of 71 ms at 196/min, and the delta wave has gone, because the impulse now travels down the AV node and returns up the pathway. A retrograde P wave sitting after the QRS and separate from it favours AVRT over typical AVNRT. There are no flutter waves, and an abrupt onset at 196/min is not a sinus tachycardia.

What is the first-line treatment?

AVagal manoeuvres, such as the modified Valsalva Correct answer Your answer
BSynchronised DC cardioversion Your answer
CIV amiodarone Your answer
DIV digoxin Your answer

In a stable patient with a narrow-complex SVT, vagal manoeuvres come first, followed by IV adenosine if they fail. Because orthodromic AVRT depends on the AV node, blocking the node terminates it. DC cardioversion is reserved for the haemodynamically unstable patient.

Stage 3 of 3

The tachycardia terminates with a modified Valsalva manoeuvre and sinus rhythm with pre-excitation returns. He is referred to the EP service.

If he later presented with pre-excited AF, which treatment would be contraindicated?

AIV verapamil Correct answer Your answer
BIV procainamide Your answer
CIV ibutilide Your answer
DSynchronised DC cardioversion Your answer

Blocking the AV node in pre-excited AF pushes conduction towards the pathway, with a risk of degeneration into VF. For that reason verapamil, diltiazem, beta-blockers, adenosine, digoxin and IV amiodarone should all be avoided. An unstable patient needs DC cardioversion, while a stable one can be treated with procainamide or ibutilide.

What is the definitive management?

ACatheter ablation of the accessory pathway Correct answer Your answer
BLong-term beta-blocker Your answer
CPill-in-the-pocket flecainide Your answer
DImplantable cardioverter-defibrillator Your answer

Symptomatic WPW is an indication for an EP study and catheter ablation, which the 2019 ESC guidelines make a Class I recommendation. Ablation has a high success rate and a low complication rate, and it removes the substrate for both AVRT and pre-excited AF.

Diagnosis

Wolff-Parkinson-White syndrome, with ventricular pre-excitation and orthodromic AVRT

Both tracings come from one accessory pathway used in two different ways. In sinus rhythm the atrial impulse reaches part of the ventricle early through the pathway, which is why the PR interval is short at 80 ms, the QRS begins with a delta wave and the complex widens to 135 ms. During the episode the circuit runs down the AV node and back up the pathway, so the ventricles are activated normally: the QRS narrows to 71 ms, the delta wave disappears and the rate reaches 196/min.

The practical lesson is that a narrow, regular tachycardia with nothing unusual about it does not exclude Wolff-Parkinson-White; it is the baseline ECG that makes the diagnosis. If he ever develops AF conducted over the pathway, AV-nodal blocking drugs must be avoided, and catheter ablation of the pathway is curative.

References

Brugada J, Katritsis DG, Arbelo E, et al. 2019 ESC Guidelines for the management of patients with supraventricular tachycardia. Eur Heart J. 2020;41(5):655-720.
Appelboam A, Reuben A, Mann C, et al. Postural modification to the standard Valsalva manoeuvre for emergency treatment of supraventricular tachycardias (REVERT): a randomised controlled trial. Lancet. 2015;386(10005):1747-1753.

This tracing was generated, not recorded. It opens in the studio with every dial live.

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