Radiosurgery for ventricular tachycardia (RAVENTA): Final results of a German multicenter multiplatform feasibility trial

Stereotactic Arrhythmia Radioablation (STAR) has been used as a bail-out treatment strategy for patients with refractory ventricular tachycardia (VT).

We report the results of the method harmonized and quality assured multicenter RAdiosurgery for VENtricular TAchycardia (RAVENTA) study [1,2] as part of the STOPSTORM project (EU-Horizon-2020 Grand No. 945119) [3].

Between 11/2019 and 10/2023, 20 patients (male: 17, female: 3; age: 49-84 [median: 64] years; non-ischemic cardiomyopathy: 11/20, prior catheter ablations: 0-8 [median 2.5]; left ventricular ejection fraction [LVEF]: 10-60% [median: 31.5%]) were treated at six university centers in Germany. Median cardiac target volume determined by electrophysiological mapping and/or scar imaging (CardTV_EP/IMG) and planning target volume (PTV) were 16.5 ml (range: 6.0-87.8 ml) and 74.8 ml (range: 31.7-144.3 ml), respectively. Prescription dose was 25 Gy in all cases with PTV near minimum (D98%) and near maximum (D2%) doses of 19.3-25.4 Gy (median: 24.6 Gy) and 27.3-31.6 Gy (median: 29.7 Gy), respectively. Median treatment time was 16 minutes (range: 4-100 minutes). The primary endpoint was safety and secondary endpoints included the occurrence of VT and treatment-related toxicity up to one year after treatment.

All treatments were successfully completed and no possibly treatment-related severe periprocedural complications were noted in the first 30 days after STAR (primary endpoint). Fifteen patients reached the regular study end at one year, fourteen of them VT free, ten without further intervention, with a median LVEF of 34.5% (range: 27-55%), shown in Figure 1 and 2. Three patients died, one in electrical storm at 7 weeks, one from retroperitoneal hemorrhage at 8 months and one from underlying heart disease at 10 months, and two patients received a heart transplant after STAR (alive at study end). Overall, six patients required further catheter/alcohol ablation or sympathectomy, four of them with recurrences in or near the STAR treatment locations, resulting in a total local efficacy (freedom from index VT) of 73.7% (14/19). Combined, 37 serious adverse events were reported, all but one judged not to be possibly treatment-related. The one grade ≥ 3 toxicity possibly related to STAR was progression of heart disease in the 2nd month ater STAR requiring heart transplant during follow-up. Five and two of eighteen patients that reached 3 months follow-up showed asymptomatic pneumonitis or pericardial effusion, respectively, and were conservatively managed.

RAVENTA is the world's first multicenter multiplatform study of STAR as bailout for patients with refractory VT. Possibly treatment-related side effects were mild, demonstrating short-term safety of the procedure, and most patients had significant reductions in VT burden. Long-term follow-up and further optimization of the target definition is warranted.

Ejection fraction before and after STAR