Sinus node dysfunction unmasked during dobutamine stress echocardiography.

Area of Science:

• Cardiology
• Electrophysiology

Background:

• Sinus bradycardia and isorhythmic AV dissociation during dobutamine stress echocardiography are typically considered benign, often attributed to the Bezold-Jarisch reflex.
• These phenomena are usually transient peri-procedural events related to increased vagal efferent discharge.

Observation:

• A 50-year-old male with chest pain and syncope experienced worsening sinus bradycardia with isorhythmic AV dissociation during dobutamine stress echocardiography.
• This presentation prompted further investigation into the underlying cause of the cardiac rhythm abnormalities.

Findings:

• Invasive electrophysiological study confirmed marked sinus node dysfunction in the patient.
• The findings indicated that the dobutamine stress echocardiography unmasked a clinically significant sinus node issue.

Implications:

• Dobutamine-associated bradycardia may indicate underlying, clinically relevant sinus node dysfunction, not merely a benign physiological response.
• This case underscores the need for careful evaluation of bradycardia during dobutamine stress testing, as it may necessitate interventions like permanent pacemaker insertion for symptomatic patients.