ESTRO 2024 - Abstract Book

S16 ESTRO 2024 1 Amsterdam UMC location University of Amsterdam, Radiotherapy, Amsterdam, Netherlands. 2 Amsterdam UMC location University of Amsterdam, Cardiology, Amsterdam, Netherlands. 3 Amsterdam UMC location University of Amsterdam, Anesthesiology, Amsterdam, Netherlands Invited Speaker

Abstract:

Breath regularisation during stereotactic cardiac radioablation

Ventricular tachycardia and its successor ventricular fibrillation are life-threatening cardiac arrhythmias, which

deteriorate cardiac function and result in acute heart failure or sudden cardiac death. Treatment options include an

implantable cardioverter-defibrillator that can detect arrhythmia and restore a normal rhythm by anti-tachycardia

pacing or high-voltage shocks. However, a cardioverter-defibrillator does not stop the occurrence of ventricular

tachycardia. Anti-arrhythmic medications are prescribed to lower or prevent recurrent arrhythmias, but may not

prove effective or may result in intolerable side effects. Persistent ventricular tachycardia treated by catheter ablation

may provide long-term amelioration, but approximately 20–50% of patients may still experience complications or

unsatisfactory control of ventricular tachycardia, requiring repeated procedures 1,2 .

Stereotactic cardiac radioablation has evolved as an alternative treatment to traditional catheter ablation.

STereotactic Arrhythmia Radioablation (STAR) delivers a single, localised high-dose radiation fraction (typically 20–25

Gy) to the area where the arrhythmia occurs. A systematic review summarized that the effect of STAR is promising,

resulting in a reduction of over 85% in ventricular tachycardia episodes 3 .

Targeting the area of interest for STAR is hampered by cardiac and particularly by respiratory motion. Large internal

target volumes up to 120–284% of the gross target volume are created to account for this motion 4 , but in turn

increases the risk of damage to healthy tissues and organs at risk (e.g. stomach, bowel loop). Multidisciplinary teams

have to balance between applying sufficiently high radiation doses to the affected area of the heart, while sparing

healthy surrounding organs as much as possible. In some cases, this might lead to an underdosage of the area where

ventricular tachycardia originates. Clearly some form of respiratory motion management is required to increase

accuracy and hence efficacy of STAR.

Cardiac and respiratory motion magnitude can exceed 1 and 2 cm, respectively 5 . A recent STOPSTORM.eu consortium

review concluded that data on cardiorespiratory motion for STAR is still limited and heterogeneously reported, and

that cardiorespiratory motion is highly patient-specific even under motion-compensation techniques 4 . Such motion

compensation techniques include, amongst others, respiratory-binned 4DCT, abdominal compression, and (MRI

guided) gating and tracking, with or without short breath-holds in inspiration or expiration.

Breath-holding is the only technique that requires active participation of the patient, but patients with ventricular

tachycardia may have difficulty with breath-holding 6 and particularly with the repeated room-air based breath-holds

needed for the full duration of STAR.