Stereotactic arrhythmia radiotherapy for refractory ventricular tachycardia: Interim safety and efficacy results from the ongoing prospective STARNL-2 trial
W F Hoeksema, E M T Dieleman, J Visser, L H G A Hopman, N H J Lobe, H A C M De Bruin-Bon, N Van Wieringen, M H Van Der Ree, P Bhagirath, H J Verberne, J J C Verhoeff, M J B Kemme, B V Balgobind, P G PostemaAbstract
Background
Stereotactic Arrhythmia Radiotherapy (STAR) is an emerging treatment modality for malignant cardiac arrhythmias. However, the number of prospective trials published to date remains limited.
Purpose
To prospectively evaluate the safety and efficacy of STAR for therapy-refractory ventricular tachycardia (VT).
Methods
This was a planned interim analysis of the ongoing prospective, single-centre Stereotactic Arrhythmia Radiotherapy in the Netherlands no. 2 (STARNL-2) trial. The STARNL-2 trial is a single-arm pre-post intervention study aiming to include 12 patients with therapy-refractory VT. Patients were treated with a single fraction of 25 Gy stereotactic radiotherapy delivered at the VT substrate. The primary endpoints for safety and efficacy are treatment related serious adverse event (SAE) rate and a 50% reduction in treated VT episodes 12-months after STAR compared with 12 months before STAR. Per protocol, a 3-month blanking period is used for the efficacy endpoint.
Results
Ten patients have been included in the STARNL-2 trial so far. One patient died prior to STAR and was therefore not included in this analysis. The median age was 71 (range 60-81), eight were male (89%) and six suffered from nonischaemic cardiomyopathy (two ischaemic and one both ischaemic and nonischaemic) with a median left ventricular ejection fraction of 32% (range 15%-50%). Before STAR, all patients were on amiodarone and mexiletine with median daily doses of 400mg (range 200-600) and 800mg (range 400-1000), respectively. The median number of previous VT ablations was 3 (range 1-4) and seven patients had previously undergone epicardial VT ablation (78%). During follow-up, two patients died from non-treatment-related causes (✝ in Figure 1), one of which due to a cardiac cause. One treatment-related SAE was observed, a grade 3 implantable-cardioverter defibrillator bitflip requiring a prolongation of hospital admission (P10; asymptomatic, no permanent damage to the device). Two patients have not reached the end of the blanking period yet and were therefore not evaluable for the efficacy endpoint. Of the other seven patients, one underwent a new epicardial VT ablation after STAR (P3). The median change in treated VT episodes was -97% (-100% - +169%); Figure 1).
Conclusion(s)
Preliminary results from the ongoing prospective STARNL-2 trial confirm the favourable short-term safety and efficacy of STAR for therapy-refractory VT. These results support the use of STAR as a promising non-invasive treatment option in future trials.Treated VT episodes pre- and post-STAR