Stereotactic Cardiac Radiotherapy for Refractory Ventricular Tachycardia in Structural Heart Disease Patients: A Systematic Review

Background: Among patients with structural heart disease with ventricular tachycardia (VT) refractory to medical therapy and catheter ablation, cardiac stereotactic body radiotherapy (SBRT) is a paradigm-changing treatment option.

Aims: To assess the efficacy of cardiac SBRT in refractory VT by comparing the rates of VT episodes, anti-tachycardia pacing (ATP) therapies, and implantable cardioverter-defibrillator (ICD) shocks post-SBRT with pre-SBRT.

Methods: We performed a comprehensive literature search and included all clinical studies reporting outcomes on cardiac SBRT for VT. Treatment efficacy was evaluated as random-effects pooled rate-ratios of VT episodes, ATP therapies and ICD shocks post-SBRT (after 6-week blanking) and pre-SBRT, with patients serving as their own controls. Post-SBRT overall survival was assessed using Kaplan-Meier method.

Results: We included 23 studies published 2017-2024 reporting on 225 patients who received cardiac SBRT, with median follow-up 5.8-28 months. There was significant heterogeneity among the studies for all 3 efficacy endpoints (p<0.00001). The random-effects pooled rate-ratios of VT episodes, ATP therapies and ICD shocks post- versus pre-SBRT were 0.10 (95% CI 0.06, 0.16), 0.09 (0.05, 0.15), and 0.09 (0.05, 0.17), respectively (all p<0.00001). The most common reported complications included pericardial (8.0%, including 0.9% late gastroesophageo-pericardial fistula) and pulmonary (5.8%). There was no change in left ventricular ejection fraction post-SBRT (p=0.3) but some studies reported an increase in mitral regurgitation. The combined 3-, 12- and 24-month overall patient survival was 0.86 (0.80, 0.90), 0.72 (0.65, 0.78) and 0.57 (0.47, 0.67) respectively.

Conclusion: Among patients with refractory VT in context of structural heart disease, VT burden and ICD shocks are dramatically reduced following cardiac SBRT. The overall mortality in this population with heart failure and refractory VT receiving palliative cardiac SBRT remains high.