Which of the following is an indication for a pacemaker?

• A. Sick sinus syndrome with symptomatic bradycardia
• B. Atrial fibrillation with rapid ventricular response
• C. Hypertrophic obstructive cardiomyopathy without conduction disease
• D. Pulmonary embolism

Answer: (A)

The main idea is that a pacemaker is indicated to treat symptomatic bradycardia from intrinsic conduction system disease, especially when the sinus node fails and causes overly slow heart rates or pauses. Sick sinus syndrome with symptoms like dizziness or syncope is a classic scenario where pacing prevents pauses and maintains an adequate heart rate, directly addressing the problem and improving symptoms.

The other scenarios don’t fit as pacing indications. Atrial fibrillation with rapid ventricular response is a problem of too-fast rate, so treatment focuses on rate or rhythm control rather than pacing to raise the rate. Hypertrophic obstructive cardiomyopathy without conduction disease isn’t driven by a need to pace the heart; management targets obstruction relief and symptoms with medications or procedures. Pulmonary embolism is an acute thromboembolic event that requires anticoagulation and supportive care, not a pacemaker.