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AF Crisis in Obstructive HCM — EECC MCQ

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HardCardiomyopathyAF Crisis in Obstructive HCMEECC

A 55-year-old man with obstructive HCM (resting LVOT gradient 85 mmHg, septal thickness 25 mm) develops atrial fibrillation. His blood pressure drops to 75/50 mmHg with pulmonary oedema. What is the most appropriate acute management?

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Correct answer: E — Urgent synchronised DC cardioversion to restore sinus rhythm and haemodynamic stability; IV phenylephrine may be needed to support blood pressure

AF in obstructive HCM causes acute haemodynamic deterioration because: (1) loss of atrial contraction reduces LV filling (critical in a stiff, non-compliant LV); (2) rapid ventricular rate shortens diastolic filling time; (3) reduced LV volume worsens LVOT obstruction. Urgent cardioversion is the treatment of choice. IV phenylephrine (alpha-1 agonist) may be needed to increase afterload and reduce LVOT gradient while preparing for cardioversion. IV vasodilators (nitrates) and diuretics worsen obstruction by reducing preload. Beta-blockers may help long-term but can cause further hypotension in the acute setting. The 2023 ESC Cardiomyopathy Guidelines emphasise prompt cardioversion for haemodynamically compromising AF in HCM.

Reference: ESC (2023): Guidelines on Cardiomyopathies