SLO 5

A 68-year-old man with a history of known Wolff-Parkinson-White syndrome presents to the ED with palpitations and light headedness. He is alert but anxious. ECG shows an irregular wide-complex tachycardia at a ventricular rate of 220–260 bpm. There is no clear P-wave activity, and delta waves are intermittently visible. He is haemodynamically stable with BP 122/78 mmHg.

What is the most appropriate initial management?

In a patient with narrow complex tachycardia and reduced ejection fraction (HFrEF), which drug is contraindicated?

A 29-year-old man is brought to the ED with sudden onset palpitations, dizziness, and chest tightness for 40 minutes. He has a known history of WPW pattern on a previous ECG (short PR interval with delta waves) but has never required treatment.

Observations:

• HR 240–260 bpm, irregular
• BP 118/70 mmHg
• RR 18
• SpO₂ 98% on air
• He is alert and haemodynamically stable

ECG: irregular broad-complex tachycardia with beat-to-beat variation in QRS width and morphology and very rapid ventricular rates — consistent with pre-excited atrial fibrillation (AF in WPW).

Question: Which of the following medications is the safest and most appropriate acute pharmacologic option in this condition?