Stereotactic Body Radiotherapy for Cardiac Arrhythmias: Current Evidence and Clinical Boundaries

Area of Science:

• Cardiology
• Radiation Oncology
• Medical Physics

Background:

• Stereotactic arrhythmia radioablation (STAR), or cardiac stereotactic body radiotherapy, is an emerging noninvasive method for arrhythmia substrate modification.
• Its biological mechanisms, dose-response relationships, and differential effects on atrial and ventricular substrates are not fully understood.

Purpose of the Study:

• To review the current evidence for STAR in treating ventricular tachycardia (VT) and atrial fibrillation (AF).
• To highlight the challenges and future directions for AF-STAR, emphasizing disease-specific target design, motion-aware planning, and safety surveillance.

Main Methods:

• Review of prospective studies and pooled analyses for VT-STAR.
• Analysis of preclinical data and small human series for AF-STAR.
• Discussion of mechanistic uncertainties and safety considerations.

Main Results:

• VT-STAR has demonstrated significant reductions in VT burden and ICD therapies in refractory VT, establishing its role as a salvage therapy.
• AF-STAR has shown technical feasibility in selected patients, but durable rhythm control and clinical suitability are not yet established.
• Significant uncertainties remain regarding optimal dosing, target validation, and long-term safety for AF-STAR.

Conclusions:

• While VT-STAR is a valuable salvage therapy, AF-STAR requires further investigation to establish safety and efficacy.
• Key areas for AF-STAR development include defining therapeutic windows, ensuring accurate targeting, and gathering long-term safety data, particularly concerning esophageal and coronary structures.