When the Pacemaker Goes Rogue: Pacemaker-Induced Tachycardia, Syncope, and Car Crash

Area of Science:

• Cardiology
• Electrophysiology
• Medical Devices

Background:

• A 78-year-old male with ischemic heart disease and an implantable cardioverter defibrillator (ICD) experienced syncope preceding a car accident.
• Initial investigations ruled out acute coronary syndrome and neurological causes for the syncope.

Purpose of the Study:

• To investigate the cause of syncope in a patient with an ICD.
• To evaluate the role of pacemaker-mediated tachycardia (PMT) in inducing syncope and hemodynamic instability.

Main Methods:

• Device interrogation revealed a history of PMT, which was subsequently provoked via atrial threshold testing.
• The induced PMT resulted in significant symptomatic hypotension (mean blood pressure < 50 mmHg).
• Management involved reprogramming the dual-chamber ICD (DR ICD) from DDD to DDIR mode to prevent atrial tracking and terminate PMT.

Main Results:

• Reprogramming the DR ICD effectively terminated PMT episodes.
• The patient experienced no further episodes of presyncope or syncope during follow-up.
• The adjusted device settings prevented recurrent PMT, resolving the patient's symptoms.

Conclusions:

• Pacemaker-mediated tachycardia can precipitate severe hemodynamic instability and syncope, particularly in patients with underlying cardiac dysfunction.
• Meticulous evaluation and reprogramming of cardiac devices are crucial for managing PMT and preventing associated adverse events.
• Mode switching in ICDs is an effective strategy to manage PMT when other programming adjustments are not feasible.