The time course of left ventricular function in patients treated with stereotactic arrythmia radioablation (star) for sustained ventricular arrhythmias: a prospective clinical evaluation

Background

Stereotactic arrhythmia radioablation (STAR) is an emerging bailout option for therapy refractory ventricular tachycardia (VT). Mortality in the first year after STAR is high, mainly due to end-stage heart failure. Pooled data show no relevant change in LVEF from pre-STAR to follow-up in survivors, although improvement has been case-reported and linked to mice data. In patients with electrical instability, factors such as stunning after ICD shocks, LVEF decline from incessant VT and negative inotropic drugs may temporarily depress LV function independent from STAR.

Aim

To evaluate the time course of left ventricular function in patients requiring STAR for drug and catheter ablation refractory VTs.

Methods

Between April 2019 and June 2025, ten patients with therapy refractory VT treated with STAR in a single center were prospectively included. All received a single 25 Gy fraction. LV ejection fraction, LV global longitudinal strain (LVGLS) and valvular function were assessed by echocardiography at four timepoints: (i) baseline during electrical stability within the year before STAR, (ii) at first VT presentation prompting STAR, (iii) immediately before STAR and (iv) at three months follow-up.

Results

Ten patients were included (age 67.7±10.3 years, 9 male, 3/10 post-MI, 7/10 non-ischemic etiologies). Presenting arrhythmias were acute electrical storm in three, incessant VT in three and recurrent ICD shocks in four. All had prior VT ablations (median 3, IQR 2–4), with the last ablation at STAR admission in 7/8. All were on amiodarone and 4/10 on Class 1 agents. Median time between electrical instability and STAR was 27 days [17–37]. Median CardTV was 57 ml (24–92). Two patients died before three-month follow-up, one from surgical bleeding after two days and one from worsening heart failure after 28 days.

LVEF was 34±10 percent in the preceding phase, 31±9 percent at presentation and 28±7 percent before STAR. At three months it was 32±10 percent. LVGLS was 9.7±3.3 at baseline, 7.3±3.3 at presentation, 7.2±3.2 before STAR and 8.3±3.3 during follow-up. Median whole-heart dose was 6.7 Gy (IQR 3.8–8.5) with no relation to functional changes. Five relevant valvular changes (≥1 grade increase) occurred from baseline to follow-up (one mitral, one tricuspid and three aortic regurgitations).

Conclusion

This prospective study shows that LVEF and LVGLS declined from baseline to electrical instability and STAR but recovered to near-baseline levels by three months. The arrhythmic presentation and non-STAR interventions appear to drive these changes, while STAR may affect valvular function. Further studies are required to determine whether lack of LV recovery after STAR should be considered an adverse event.Effect of STAR on cardiac function