ESTRO 2024 - Abstract Book

S1913

Clinical - Mixed sites, palliation

ESTRO 2024

Figure 1: Number of appropriate shocks and total tiem in VT for the six months before and after cSABR

A total of seven patients have been treated at our institution between December 2021 and June 2023 (ischaemic cardiomyopathy n = 4, male n = 5, mean LVEF 25% (range 20-35%)). One further patient was accepted and planned for treatment, however, unfortunately died prior to treatment from unrelated co-morbidities (sepsis, AKI on CKD). All patients were treated with a 25Gy single fraction. The indication for treatment was refractory VT in 6 patients. One patient had refractory premature ventricular complexes (PVC) which represented the primary indication for treatment, however had also experienced recurrent ventricular arrhythmias including sustained VT and ventricular fibrillation (VF). All patients had experienced a recurrence of VT despite the use of amiodarone. Five patients had undergone multiple invasive catheter ablation procedures (range 2-5) prior to cSABR. The other two patients had contraindications to invasive catheter ablation. Median duration of follow up to September 2023 was 5 months (range 1-19 months). Treatment was well tolerated with only minimal acute toxicity. Five patients experienced a reduction in the number of shocks following cSABR with median number of shocks prior to cSABR 6 (range 0 – 9) which reduced to 0 (range 0 – 38) following cSABR (see figure 1). 6 patients experienced a reduction in VT burden following cSABR with median duration of VT prior to cSABR 9554s (range 264 – 57242s) which reduced to 803s (range 0 – 5414s) following cSABR. 5 patients experienced a reduction in ATP therapies following cSABR with median number of ATPs prior to cSABR 66 (range 18 - 282) which reduced to 7 (range 0 - 122) following cSABR. Two patients have died since treatment, at intervals of 10 and 20 months after treatment, both of whom died secondary to progressive refractory heart failure.

Conclusion:

Our initial findings are promising for a clinically significant reduction in VT burden and treatments for VT following cSABR, though this does not currently reach statistical significance due to the low patient numbers. This is likely to translate into a meaningful improvement in quality of life for these patients who have limited further treatment options for their arrhythmia. Two out of seven patients died within two years of treatment, however this must be viewed in the context of a complex patient population with multiple co-morbidities and impaired pre-treatment cardiac function. Further follow-up is required in order to determine the duration of benefit following cSABR, as well as identify those patients most likely to benefit from treatment.