A 35-year-old woman presents to the ER with SVT at 180 bpm. BP is 110/70 mmHg. She has no structural heart disease. Vagal manoeuvres fail. What is the drug of first choice for acute termination?
- A IV verapamil 5 mg
- B IV metoprolol 5 mg
- C IV adenosine 6 mg rapid bolus, followed by 12 mg if no response ✓
- D Synchronised DC cardioversion
Correct answer: C. IV adenosine 6 mg rapid bolus, followed by 12 mg if no response
Explanation
Adenosine (6 mg IV rapid bolus followed by a 12 mg flush if ineffective) is the first-line pharmacological treatment for haemodynamically stable regular narrow-complex SVT (AVNRT or AVRT) after failed vagal manoeuvres, per AHA/ACC 2015 SVT guidelines. Its ultra-short half-life (10 seconds) and selectivity for AV nodal conduction make it ideal. It terminates 90–95% of AVNRT/AVRT. Verapamil is an alternative but has a slower onset and requires ruling out pre-excitation. DC cardioversion is reserved for haemodynamically unstable SVT.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.